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DIY – FIX the DRIVER SIDE HVAC MIX DOOR NOISE

 
Old 07-05-2012, 01:18 AM
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DIY – FIX the DRIVER SIDE HVAC MIX DOOR NOISE

HOW TO LUBRICATE THE HVAC DOOR LINKAGE on the DRIVER SIDE

HVAC = Heating, Ventilation, and Air Conditioner system, AKA Climate Control System
FSM = Factory Service Manual
Left side = driver side
Right side = passenger side

The problem is a creaking or ‘groaning’ noise from under the driver side dash, by the center console. This problem is mentioned in multiple threads on this forum, with references to a corrective TSB. But I could not find the TSB online, so got a hard-copy from my dealer. Perhaps others will benefit from my experience of doing the corrective procedure myself.

If your RDX is still under warranty, the dealer should perform this corrective procedure (the TSB) without charge. Both my local dealers offered to do so for me. I chose to do this fix for myself, as I mostly just prefer to do my own work when possible.

Please read through this entire post before beginning the procedure, in order to understand what is required, and to answer any questions that you might have.

This post is for the driver’s side HVAC mix door only. But the general information should apply to the passenger side HVAC doors and linkages as well, if they are making any noise. Pictures below are from both the TSB (Acura Technical Service Bulletin) and FSM (factory service manual), as well as under the dash of my own 2009 RDX.

NOTE: since the parts are all plastic, they will be very brittle if it is cold outside, and more likely to break. And you may not enjoy working in the cold either. My suggestion is if it is below 40 degrees, that you let the dealer perform this procedure, where the mechanic can work inside, with the car at a more normal temperature.

RELATED LINKS:
The following links are related to this problem:

https://acurazine.com/forums/showthread.php?t=813245post #16 describes a fix, no pictures

https://acurazine.com/forums/showthread.php?t=682368 – post #19 describes HVAC system motor and door noise troubleshooting

https://acurazine.com/forums/showthread.php?t=684991– post #4 describes how to run the Climate Control System self-diagnostic function

https://acurazine.com/forums/showthread.php?p=13855559&posted=1#post13855559 – general description of the problem

TSB (technical service bulletin) REPAIR STEPS:
Acura Service Bulletin 09-028, February 12, 2010 applies to 2007-09 RDX – ALL
Driver’s Air Mix Door Creaks or Squeaks

SYMPTOM
When the A/C is on and you adjust the vent temperature, there is a creak or squeak from under the instrument panel.

PROBABLE CAUSE
Lack of lubrication on the driver’s air mix door linkage.

CORRECTIVE ACTION
Lubricate the moving plastic parts of the driver’s air mix door linkage.
********************************

These are the basic steps to complete the TSB. Keep in mind that all of the parts are plastic, and work carefully accordingly.

Make certain that the ignition switch is OFF, and in LOCK position. Remove the ignition key for safety.

Engage the emergency brake, if only to move it out of your way.

Adjust the steering wheel by pulling it out and up as far as it will go, and latch.

Remove the lower trim piece under the steering wheel/ dash.

Remove the accelerator pedal.

Remove the Driver Side Air Mix Motor.

Disconnect the heater water valve cable-end from the lever, then remove the lever.

Grease/ lubricate appropriate parts.

Re-assemble in reverse order, and test.


WHAT IS THE PROBLEM?
When the Driver Side Air-Mix Motor runs, there is a noise, sort of a low groan or whine or squeak. This is caused by a lack of lubrication in the linkage, and rubbing of moving parts. The Driver Mix Motor opens/ closes the heater water-hose valve, as well as the air flow mix door (on the driver side).

This noise often occurs just when starting the vehicle, especially if the ambient temperature is different when starting, from the vehicle interior temp when the vehicle was last parked. This is because the auto-climate control system moves the air mix door to adjust for the ‘new’ current ambient temperature, to warm-up or cool the interior.

As a point of reference, my wife did not tell me about this problem until it had been happening for at least a year (oh yeah, I have been hearing that noise since last spring). Since the only time I usually drive the vehicle is to get gas, the vehicle would already be warmed up and I never heard any noise.

But my point is that the noise began after only two years of ownership. I point this out because it may mean that this corrective procedure, to lubricate the door linkage, may be required at regular intervals.

/BEGIN DIGRESSION:
The RDX noise is simply un-lubricated moving HVAC linkage-parts. There is nothing wrong with the HVAC driving-motor itself, which is good, since there appears to be no way to disassemble the motor itself to lube it, without damaging it. Anyway, the driver-side motor currently costs about $50. The similar motor on my Chevy 4x4 cost $270 plus installation cost of another $150. And the reason for replacement of the Chevy motor was that the internal plastic gears had chewed themselves into small pieces, after 12-years. Probably the same will eventually happen with the RDX motor, so that it is pointless to worry about lubricating the RDX motor itself. At least the RDX motor is easily accessible, not so much for the Chevy motor, which is why I let the dealer replace it.
END DIGRESSION/


HOW LONG TO FIX THE PROBLEM?
The Acura TSB allows a flat rate of 18 minutes for this warranty procedure. It took me just over 3 hours, but I am very slow (and obsessively methodical) and took pictures. Read this post and decide for yourself if you wish to undertake this procedure.


HOW TO VERIFY THE PROBLEM?
This procedure will completely cycle (move) the driver side HVAC motor and linkages and heater valve cable.

It is not necessary to run the engine during verification, and it will be a lot safer if you do not. A kneeling pad will be very handy and helpful. Sears makes a Craftsman one, but I used a garden kneeling-pad from K-mart which I purchased on sale for $1.00

Open the driver side door as far as possible. Engage the emergency brake. Move the driver’s seat back all of the way. Then kneel beside the driver’s door on the ground/ on your kneeling pad.

Turn the ignition key to the ACCESSORY position. Turn off the radio.

Turn the ignition key to the RUN position (do not start the engine). Place the HVAC system in DUAL mode, and AUTOMATIC mode. If in DUAL mode, only the driver side motor/ linkage will move.

While looking under the dash at the HVAC driver side motor, use the driver-side ARROWS on the HVAC control to slowly/ rapidly increase and decrease the temperature, from maximum to minimum repeatedly. You can use this same method to diagnose the passenger side motor(s) and linkage, by using the passenger-side ARROWS.

You are most likely to hear the noise, if the vehicle has been sitting for several hours, or overnight. This is because if the vehicle has been running and warmed up, the HVAC system has probably already moved the linkage, and it is less likely to make any noise. In other words, noise is most likely to occur during initial movement of the linkage system.

You should have determined if the motor is defective by following this validation procedure. Just keep in mind that if there is no grease remaining on the HVAC linkage, the linkage my be binding so much that the motor cannot move. Sorry, but for any further diagnosis of the motor, you will need to check the FSM or with your mechanic.

If the motor should require replacement, it is p/n 79160-STK-A41.


TOOLS NEEDED TO FIX THE PROBLEM:
Fixing the problem is labor intensive, but fairly simple (just uncomfortable), and requires minimal tools.

Stubby Phillips #2 screwdriver, perhaps a 6-inch Phillips #2 screwdriver as well

Dow Corning MolyKote MH-62 grease: listed in the Acura TSB as Honda P/N 08798-9012 and cost of $30 for 1.5 ounce jar, enough to perform this specific TSB procedure 20 times. My Honda dealer ordered it overnight for me, and gave me a 10% discount (because I asked for it) and because I always chat with the guys on the parts desk, and because I buy my Acura parts at the Honda dealership when possible. Friendly with the parts guys (and gals) helps with the parts cost.

Synco Super Lube Synthetic Grease with Syncolon (PTFE) (optional instead of the MolyKote grease). Available from Ace Hardware store at $6 for 3 ounce-tube, item# 21030. NOTE: that is the Synco item number. Ace hardware has their own numbering system. This item may also be available from a Tru-Value hardware store, or other places. GM sells aerosol Super Lube under GM p/n 1234-6241, in GM packaging. Do not use the aerosol, as it will not apply enough grease where needed on the HVAC linkage.

Permatex Dielectric Tune-up Grease, item# 765-1824 (optional), or any other reputable brand

Permatex Clear RTV Silicone Adhesive Sealant (optional), or any other reputable brand

Permatex Blue Medium Strength Threadlocker, item# 24200 (optional), or any other reputable brand


WHICH GREASE to USE?
I am aware that there are people using white lithium or chassis grease for similar lubrication on HVAC systems. I do not recommend these or any other grease that does not say it is specifically for plastic. Some greases can degrade plastic, causing it to either soften or crack.

Both MolyKote MH-62 and Super Lube are, I believe, adequate to lubricate the air mix door linkage. Acura TSB 09-028 specifically lists the MolyKote grease. So I chose to use the MolyKote grease because my RDX is still under warranty, and the two greases have different colors. Otherwise, I probably would have used the Super Lube, as I normally use it for similar purposes. And I think that it is actually a (slightly) better choice for this application.

DOW CORNING MOLYKOTE MH-62:
Dow Corning states that this grease is “designed primarily for plastic/ plastic, metal/ metal, and metal/ plastic lubrication in electromechanical applications such as automotive HVAC components and cables”. For this particular TSB, all parts are plastic except for the end of the heater water-valve cable, which is a metal loop (fits over a plastic pin), and a metal pin on the back of the motor.

This grease is a PAO (poly-alphaolefin) synthetic hydrocarbon oil/ lithium soap grease containing “specially formulated solid lubricants”. Which solid lubricants, are not specified in any Dow Corning literature that I could find. The specific percentage formulation is not listed in the MSDS (manufacturer safety data sheet).

Generally, the technical specifications for this grease are similar to those for Mobil-1 Synthetic Chassis Grease (the red stuff). I indicate this simply as a comparison. However, note that the Mobil-1 grease is NOT specified as appropriate for plastic parts lubrication. So do not think that I am suggesting that use of the Mobil-1 grease would be appropriate for this TSB. If interested, you can find the specific technical data for the MolyKote MH-62 on the Dow Corning web site.

This grease has a slight tan/ beige color.

NOTE: the shelf life of MH-62 is 5 years, from the date of manufacture, when stored at ambient (room) temperatures in its original closed container. I cannot find a date code (that I can decipher) on the container. The date code on the Honda packaging indicates that the product that I purchased is already 18 months old.

SYNCO SUPER LUBE:
I have used both the spray and tube versions (same grease, different delivery). The Synco web site lists approximately 20 specific plastics and 20 types of rubber with which this grease is compatible. That does not mean that these are the only materials with which the grease is compatible. Dow Corning does not list specific plastics with which the MolyKote MH-62 is compatible, nor is there any indication that MH-62 is compatible with rubber.

Super Lube grease is a PAO (poly-alphaolefin) synthetic containing “polytetrafluoroethylene - PTFE”. The MSDS says that it is approximately 80% PAO, 15% white mineral oil (petroleum), and 5% Teflon (PTFE solid lubricant). Looks pretty similar to the MolyKote MH-62, doesn’t it??

Generally, the technical specifications for this grease exceed those for Mobil-1 Synthetic Chassis Grease, or MolyKote MH-62, in terms of temperature range, load carrying capability, etc. All three of these greases are rated NLGI #2, the normal requirement rating for automotive chassis grease. Technical data and the MSDS for Super Lube grease are available on the Synco web site.

Aerosol Super Lube is recommended by brand name by GM as appropriate for certain lubrication uses in GM vehicles, such as key pin-locks (doors and ignition), door hinges, and door latches with plastic/ rubber parts. I use it any time that I need to lubricate parts that are not solely metal, i.e., assemblies that involve plastic or rubber combined with metal.

Super Lube is rated Food Grade H-1 by the USDA and NSF for incidental food contact. It is rated an excellent Dielectric (like Silicone ignition grease) but does NOT contain any silicone. This grease is rated in the MSDS as non-toxic. I like using it because of this safety rating.

This grease looks translucent clear-to-white.


EXACTLY WHERE IS THE DRIVER-SIDE HVAC MOTOR?
These pictures show the area where you will be working, and the location of the relevant parts:

PICTURE: HVAC motor location



PICTURE: HVAC motor



SHORT-CUT SOLUTION?
It may be possible to stop the noise with this short-cut. On my own RDX, there was plenty of grease everywhere, except in the door lever-slot. If your vehicle is out-of-warranty, and you do not wish to perform this complete procedure, it is possible to lube the HVAC door lever without disassembling anything. Just use a Q-tip and grease to lube the slot in the door lever. You will need to use the Verification Procedure described above to move the door lever to the best position for lubricating it.

This picture below is not very clear, but if you actually look under the dash, you will see the slot that (probably) needs grease. There was some grease in my own door slot, but it was dried and there was not very much.

How much grease to add? Too much and it will drip down behind the dash/ console, where you cannot get to, in order to clean. Look carefully before you grease the lever-arm. Too little, and well, you can just go back and add a bit more. It definitely requires more than just a thin layer inside the slot.

NOTE: those brown specs on the motor steel mount, is rust. I suppose that is from the high-humidity winters here, and why most parts are plastic.

PICTURE: HVAC door lever



REMOVE THE DRIVER’S DASHBOARD LOWER COVER:
The FSM (factory service manual) states that this cover should be removed. However, I was unable to determine just what this cover actually is. Whatever it is, I did not remove it.


REMOVE THE DRIVER’S DASHBOARD UNDERCOVER:
The TSB does not state that this part should be removed, but the FSM does. You will be much happier if this part is removed, because it partly masks/ obstructs removal of the Air Mix Control Motor.

PICTURE: instrument panel garnishes


There are two clips and one lock knob holding the part in place.
PICTURE: HVAC undercover knob


Turn the lock knob (B) 90 degrees, in a counter-clockwise direction, when looking upward from under the dash. Turning it clockwise will break it. Righty – tighty, lefty – loosey. If you do break this part, a new part is about $4, p/n 83113-SV4-003YC.

When reassembling, remember that the knob is only a clip, not a screw or bolt. Turn it only 90 degrees. If you attempt to “tighten” it, the pin on the back will break. And make certain that the pin is completely through the hole/ slot in the metal support, before turning the knob.

PICTURE: HVAC duct



Pull down gently on the right side edge of the undercover, to detach the two clips. So says the FSM. Actually, you will need to pull hard enough to break the plastic, unless care is taken. So, support the part to which the Undercover is attached, the heater Duct assembly, by holding it with your hand. The problem is that the clips on the Undercover ends are metal, pushed through slots in the plastic Duct. Do not jerk – just pull firmly until the clips release. I would suggest one of those plastic removal tools, but I do not see a way to insert one between the Undercover and the Duct.

Without support, the plastic duct will break as it tries to pull away from the side of the heater box, or the heater box mount will break. The heater duct is screwed to the side of the heater box with two screws, and both parts are plastic. If the heater duct is broken, a new part is about $3, p/n 79101-STK-A41.

If the heater box duct-mount breaks, you are screwed, since the dash would require removal to replace the side of the heater box.

The Undercover clips are pushed into a square shaped ear on each side of the Heater Duct, each ear has a slot in it. When I removed the Undercover part, one of the ear-slots cracked before the metal clip would release. I super-glued the hairline crack before reassembly. If the Duct in the picture below does not look OK, that is just the lighting because I did not remove the sealed outer plastic bag – it is actually a new part.

PICTURE: HVAC duct crack


PICTURE: HVAC heater unit


I also put just-a-smear of Dielectric tune-up grease on the metal clips and lock knob pin, before reassembly. That will enable easier reassembly now, and removal next time. Only a smear is required – there is no normal movement of the clips and knob-pin. And you do not want the grease to fall onto your trousers. I prefer dielectric grease here because it is thicker, and stays in place better than the Super Lube grease. I consider silicone grease too thick to use to lube the HVAC parts, especially when it is -20 degrees outside, and inside your car before it warms up.

Remember to support the heater duct assembly with your hand, when reinstalling the undercover.


REMOVE THE ACCELERATOR PEDAL MODULE:
When you go to remove the Accelerator Module, you will see that there is a NOTICE label on the floor next to it, concerning the air bag system. But read the note carefully, and you will find that it refers to the steering column, not to the Accelerator Module. So there is no worry about removing the Accelerator.

Disconnect the 6-pin plug-connector. The plug-release is on the back-side of the plug, in the picture below. That is, the side of the plug toward the HVAC motor. Since you cannot see it, unless you use a mirror, locate the release with your fingers. Press firmly on the release before pulling the plug free. The accelerator plug-release is very similar to the release on the HVAC motor electrical plug, shown clearly in the next section.

PICTURE: HVAC accelerator plug



Remove the two nuts. Pull the module off the studs.
PICTURE: HVAC accelerator module



REMOVE THE DRIVER’S AIR-MIX CONTROL MOTOR:
Disconnect the 7-pin plug-connector. The release is on the front side of the plug. Press firmly on the release before pulling the plug free.

PICTURE: HVAC motor plug



Remove the three screws. Pull the motor off the heater unit.
PICTURE: HVAC motor



REMOVE THE HEATER WATER-VALVE LEVER FROM THE HEATER UNIT:
Remove the screw and the plastic pan washer.

Remove the rubber donut from the end of the pin projecting through the round end of the Water Valve Cable. The donut is not shown in the picture below, but there was one on my car. Check the pictures above for the rubber donut. It is also not listed as a separate available part, so do not lose it.

When replacing the rubber donut, consider rubbing ArmorAll or silicone grease thinly on it, to prevent it from drying out and cracking. Remember, it is directly where the hot heater air will blow onto it.

And if your RDX is missing the rubber donut, don’t ask me about it. Again, it is not listed in the parts list. It seems to be there just to help prevent the cable end from coming loose from the lever pin, but not really necessary.

PICTURE: HVAC water valve lever



To detach the cable from the lever, it will be necessary to pull the white cover on the cable, away from the clip on the side of the heater box-unit. The clip is spring loaded, and it is necessary to use your thumb or finger to open the clip while pulling the cable free. Please note the position of the white cover in the clip. It must be returned exactly to the same position during reassembly. Otherwise, the cable will not be able to completely open and close the water valve. Be sure to check for complete cable movement after reassembly, by testing using the verification procedure described at the beginning of this post.

Detach the end of the water valve cable from the lever. And pull the lever off the heater box-unit.

Apply Molykote MH62 Grease to both sides of the lever’s pivot seat area. [ed: Also apply a smear of grease to the pin which holds the Water Valve Cable end (red arrow). This is my suggestion]

Reinstall the lever, reattach the water valve cable [ed: into the clip on the heater box and the end to the lever], and reinstall the washer and the screw with light torque. The washer should rotate easily. [ed: please see the section below titled ASSEMBLY CONCERNS]

[ed: Apply some grease to the slot in the mix door lever (red arrow). The pin on the back of the Motor, shown in the next section, inserts into this slot. I believe that too little grease in this slot was the cause of the noise on my own RDX]


GREASING THE AIR-MIX CONTROL MOTOR:
Apply grease to the pin [ed: which fits into the slot on the air-mix door lever, shown in the previous section picture]. Apply grease to the groove on the air mix control motor. [ed: The pin on the Water Valve Lever fits into this groove/ slot, make certain of this during reassembly].

PICTURE: HVAC motor back-side


Reinstall the air mix control motor.

Reinstall the accelerator pedal module, and torque the nuts to 13 Nm (9.4 lb-ft). [ed: the nuts are lock-nuts, but after disassembly they were a bit looser, so I replaced them using the BLUE Permatex threadlocker liquid]


ASSEMBLY CONCERNS:
The following assembly procedure will at first seem too complicated. But it is really important when assembling plastic parts. And once you do the first screw, you will see that it is not really that difficult. This procedure is important because you may need to disassemble and re-grease the HVAC motor and levers again someday. Unfortunately, I have seen many dash plastic parts broken by ham-fisted dealer mechanics who work fine with metal nuts and bolts, but just apply too much force with plastic parts and screws.

The HVAC parts are plastic, and the screws are metal. The screws are self-tapping, meaning that they cut their own threads into the plastic stud-holes. So the screws will not loosen, when assembled the first time.

But removing the screws will slightly-wear the plastic threads in the studs. The screw will seem a bit looser when re-installed. Do not over-tighten when replacing the screws, or the studs will crack.

Replace the screws as SNUG, not TIGHT. Tight is how you fasten together metal nuts and bolts. Snug is when the parts and screw-heads just touch. Then barely turn the screw, only 2-3 more degrees to ensure that everything is touching. Remember that a quarter-turn is 45 degrees of rotation.

To prevent the screws from vibrating loose, and to prevent wear on the plastic internal threads, assemble with clear Silicone Sealant. The Sealant will act as a lubricant, preventing any wear. But that also means you must be very careful to only turn the screws until SNUG, not TIGHT. The Sealant will also act AS glue, but not LIKE glue. That means that the Sealant will prevent the parts from loosening, but when removing the screws no extra effort will be required.

This method is especially important when replacing the screw that holds the Water Valve Lever, because that screw should be installed so that the lever (and washer) can easily rotate. Just do not get any Sealant on the parts that are to be greased. So push the screw through the lever, after greasing, and BEFORE putting Sealant on the end of the screw. Also, note that the screw-head and washer fits into a depression on the back-side of the motor housing. So even if the screw begins to loosen, it cannot fall out.

Do not apply too much Silicone Sealant. Push a screw into the opening of the tube of Sealant. Then remove all Sealant except for some in the screw threads. Use the paper stem of a Q-tip (not the cotton tip). If too much Sealant is used, it will pool in the bottom of the plastic stud-hole, and break the stud from hydraulic pressure. A little Sealant in the screw threads will just be forced up the threads and out under the screw head, as the screw is tightened.

Do not under any circumstances put Silicone Sealant directly into the screw stud-hole. Excess sealant will have no way out of the hole when the screw is installed, because the hole is a blind-hole (no bottom exit). The stud will crack from hydraulic pressure.


GREASING THE STEERING WHEEL ADJUSTMENT PARTS:
While the HVAC motor is out, and before reassembly, now is a good time to check the grease on the steering wheel position-adjustment parts. Look way up under the dash.

I did not need to add any grease, but I did use a Q-tip and/ or a screw-driver to push the extra grease back into those places where it had been pushed away. Just unlatch the steering wheel lock, and move things around, to determine which parts are moving and touching. And you may want to remove any old dried grease.

If you do need to add some grease, the same grease used on the HVAC parts will work well. Just do not put too much grease, because if it falls down, it will land on your wife/ GF’s lap. Very bad.

CHEERS.
-----eof

Last edited by dcmodels; 07-05-2012 at 01:27 AM.
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Old 07-05-2012, 03:52 PM
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Excellent post! Possibly the most helpful post in DIYs as everyone seems to have this problem.

I was just getting around to doing this (I just love crawling under the dashboard -- they should have a yoga pose named for that).

I think I'm going to go with the Super Lube, and would like to mention that is recommended to clean out old grease before adding different grease as many are not compatible.
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Old 07-06-2012, 12:13 AM
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Originally Posted by 737 Jock View Post
Excellent post! Possibly the most helpful post in DIYs as everyone seems to have this problem.

I was just getting around to doing this (I just love crawling under the dashboard -- they should have a yoga pose named for that). ...
Thanks for the complement. I had never tried the kneeling board idea before, and found it much better than my usual laying on my back on the floor under the dash, which I still had to do at least once.

Originally Posted by 737 Jock View Post
... I think I'm going to go with the Super Lube, and would like to mention that is recommended to clean out old grease before adding different grease as many are not compatible.
Yes, sorry, I just sort of assumed to clean the old grease. I did that anyway, even though I used the MolyKote, because old grease tends to dry-out a bit over time.

For any other use, Super Lube is pretty compatible with most Lithium based greases, which is most any grease that is used on a car. I just mention that in case you want to use it for something else, and it is difficult to really remove any old grease, such as in a door hinge or door lock.

CORRECTION to ASSEMBLY CONCERNS: in the original post.
The following assembly procedure …

Replace the screws as SNUG, not TIGHT. Tight is how you fasten together metal nuts and bolts. Snug is when the parts and screw-heads just touch. Then barely turn the screw, only 2-3 more degrees to ensure that everything is touching. Remember that a quarter-turn is 45 degrees of rotation.

CORRECTION: a quarter-turn is 90 degrees of rotation.

You would think that an engineer (myself) would remember that. Anyway, don’t over-tighten screws into plastic parts.
-----eof
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Old 11-09-2012, 06:35 PM
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perfectly fixed my issue. Thanks a lot for the info!
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Old 05-31-2013, 01:25 AM
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So glad you guys posted this. I'm doing this procedure first thing in the morning. Thanks!
-Joshua
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Old 02-10-2014, 10:20 AM
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I finally got around to doing this over the weekend and it was really dry, I took the whole motor off and lubed it up really good in all the trenches, its quiet now when the temp is adjusting automatically or manually now. I used the official honda grease mentioned above, Thanks again for the great info.
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Old 04-12-2014, 03:38 PM
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Thanks for the writeup, I'm going to attempt some of this myself. Would you mind fixing the photos? Some of them no longer work.
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Old 04-14-2014, 04:18 AM
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Originally Posted by QFT View Post
Thanks for the writeup, I'm going to attempt some of this myself. Would you mind fixing the photos? Some of them no longer work.
OK, those *free* picture posting sites eventually delete pictures.
Attached Thumbnails -hvac-instrument_panel.jpg   -hvac-motor-overview.jpg   -hvac-door-lever.jpg   -hvac-instrument_panel_garnish.jpg   -hvac-undercover-knob.jpg  

-hvac-duct.jpg   -hvac-duct-crack.jpg   -hvac-heater_unit.jpg   -hvac-accelerator-plug.jpg  
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Old 04-14-2014, 04:24 AM
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and the remaining pictures, in the same order as in the original post:
Attached Thumbnails -hvac-accelerator-module.jpg   -hvac-motor-plug.jpg   -hvac-motor-removal.jpg   -hvac-water-valve-lever.jpg   -hvac-motor-back-side.jpg  

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Old 07-30-2014, 09:06 AM
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I performed this fix on my 09 RDX. Thanks dcmodels!

I forgot to plug in the accelerator cable before starting up. The instrument panel was flashing all kinds of warnings (Check emissions system, check brake system, check transmission, check SH-AWD system, check VSA system etc). Engine was revving sporadically. As you can imagine I was freaking out for a few seconds. After plugging the connector back in, everything work fine except I still was receiving the Check Emisssions System warning.

To get rid of the warning message I performed the "gas pedal" ECU reset. You can find different variations of this procedure in the forums. Here is what I did:

1. Sit on driver's seat with all doors closed.
2. Turn ignition key position to ON (II), the position before starting the car.
3. Turn off A/C and radio.
4. Press down on the gas pedal. Hold it for about 10 seconds. If you look at the check engine light on the instrument panel while holding down the gas pedal, you will eventually see the light go off.
5. After seeing the light go off, hold it for an additional 5 seconds. Turn the key to the LOCK (0) position while keeping the gas pedal pressed to the floor.
6. Start the car and enjoy.
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Old 09-03-2014, 11:22 AM
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Awesome write up dcmodels. I am going to try and do this at work seeing as there is an abundance of moly and all my tools. just started groaning a couple days ago. not bad considering it has 140,000 kms on it. not to self, dont forget to plug in accelerator pedal before starting the car.
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Old 11-16-2014, 03:49 PM
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Fantastic DIY by dcmodel. I did this today as I had the dreaded groan. Worked like a charm. A few notes:

I used the SuperLube grease, in the tube.

I was surprised to see that when everything was disassembled, there was actually quite a bit of grease - some reasonably fresh tan colored stuff. I suspect a dealer had addressed the issue in the past, but it was still groaning and I was worried regreasing might not work.

I used a little well-directed SuperLube spray on the two metal clips of the undercover prior to removal, containing the overspray by using a towel. The clips popped out easily and I supported the upper piece too. I did discover the same hairline fracture that dcmodels reported above - doh! Maybe the dealer did it in the past, or it was me? In any case the plastic is so thick there, that it didn't seem to matter much. Everything went back together just fine and the clip is still held in tight despite the fracture. There is really no stress at all on the piece once its in place.

Otherwise ez pz thanks to the great DIY. Only tough part was yoga-cramming myself under the dash, and I'm only 5'7" and skinny.

Last edited by Kaputnik; 11-16-2014 at 03:53 PM.
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Old 01-21-2015, 12:50 PM
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Thanks.. I will try following the exact steps....
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Old 01-21-2015, 12:51 PM
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for some reason the pictures not showing... any idea?
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Old 01-21-2015, 04:55 PM
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Originally Posted by fwakeel View Post
for some reason the pictures not showing... any idea?
I can see them a few posts up. ?? Make sure you are logged in - go up a few posts and click on the jpeg thumbnails if you can't see them.
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Old 10-26-2015, 06:38 PM
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Thanks to dcmodels. I fixed the driver's side HVAC groan within an hour and now it is all quiet. I used Super Lube and Q-tips, followed the steps and took my time not to break anything. I was able to remove the one motor screw by using a 7mm wrench and not having to remove the dash undercover (all three phillips screws also have hexagon sides).
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Old 11-16-2016, 11:46 AM
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Hey first post here and I'm reviving this thread. Thanks to dcmodels for the detailed instructions. Like hhrdx08 I tried to get around pulling the undercover by accessing the screws directly. I found I could get at the Philips screws using a small ratcheting screwdriver (like this one: https://www.amazon.com/gp/product/B000XYOUS6/ ). Now just days after completing, I swear I'm hearing a crunchy gears sound from the passenger side. I'm assuming there's a similar motor on the other side. Anyone have experience replacing it?
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Old 06-10-2017, 02:07 PM
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thanks to the DIY. I ended up paying the dealer 60 dollars get this done (too lazy to do it myself). Noise went away afterwards. Thanks!
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Old 12-27-2017, 10:42 PM
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"You last visited 07-09-2014"

Well I'm back to say thank you for this lovely write up.
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Old 04-23-2019, 03:17 PM
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This thread concerns a noise. The only thing about the noise (2007 RDX) that really concerns me is that something is wearing out too fast that will be expensive/difficult to repair. Otherwise, the noise doesn't greatly bother me. Maybe it's like a tooth that hurts a little that isn't decaying.

Any knowledgeable comment on this point would be welcome.
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Old 04-23-2019, 05:46 PM
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Trouble is, as the Verification Procedure reveals, my Air Mix Control Motor won't hold still. It sort of acts like it's "hunting" - being driven by a sensor (Cabin Temperature?) that's hyper-sensitive. It never stops moving - back and forth in short increments/decrements as I can see during the Verification Procedure. This produces noise that seems to be just-about constant. To my ears, the sound is that of a urethane door seal rubbing back and forth against the (plastic) surface that it seals against. I've ordered a new control motor ($50, as advertised), for which I entertain slight hopes that it will cure my problem.

If it doesn't, I will next turn my attention to cleaning/replacing my Cabin Temperature Sensor. I guess my 2007 RDX may turn out to be the only example to manifest this flavor of the problem. There seems to be plenty of good grease in the slot, by the way.

Last edited by pottsf; 04-23-2019 at 05:48 PM.
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Old 04-25-2019, 12:22 PM
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Their is a fix for it, check the stick notes 📝 in the matinence thread 🧵. I have the problem but just leave it alone, the more I use the hvac weirdly the less noise it makes...
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