Waukesha

For a long time my 2001 Acura TL (~233k miles) A/C system works, but weakly. Today, when driving at a constant speed on a freeway or local streets, with air recirculating, at ambient 87F, the A/C blows air as low as 38F and as high as 50F as the pump cycles on and off. Without air recirculating the A/C blows about 44-55F. Then after turning off the car and resting for a while (say to go into a store) and starting again, the A/C only blows in the 50sF with air recirculating.

So when I got home (the car rested for an hour) I measured the low pressure (LP) and high pressure (HP) to diagnose. While parked in the garage, at idle, with A/C on max, ambient air at 87F, windows open and no recirculating air, the LP=35psi and HP=200psi, with blowing air at 58F. The pump stayed on continuously (no cycling on/off). After about 10 mins of running the LP=40psi, HP=210psi, and air blowing at 60F.

I am not a mechanic, but from my research, aren’t those pressures with in spec?

So I did the diagnostic test from the SM where I hold the climate control panel buttons “off” and “auto” at the same time and got an error code “I” with is “open in air mix control motor circuit.”

I intend to let the car cool overnight and take the same measurements at idle and see if I get the same pressures but lower air blowing temps (I will update results).

Has anyone experienced this or something similar?

Saudade

What was the humidity? RH has a big impact on output temps. The engine needs to run about 1500rpms to take the pressure and output temp readings.

The "air mix control motor" is AKA the blend door actuator. If it's not fully blocking air flow through the heater core, it will also affect your output temps. Are you able to adjust the heat?

Waukesha

Thanks Saudade. In regards to the readings, I was taking the readings at about 60%RH and about 800RPM.....so the ideal HP/LP pressures are based on a reading at 1500 RPM? Is it normal to have two people to properly read the gauges? One person to hold the engine at 1500RPM and the second to read the gauges? In regards to the blend door actuator I can adjust the heat....but there is a weird glitch. This glitch only matters in Spring and Fall when the morning is cool and the evenings are hot. The glitch is if the climate was turned to cold at night, and in the morning I want heat, I have to turn the climate knob all the way to maximum then I can turn it down to say 80F or so. If I just turn it from 60F to 80F in the cool morning the blower motor will kick on when the engine warms up, but will blow cold air.....until I turn it all the way to 90F, then back to 80F and warm air comes out. I replaced the actuator a long time ago but didn't fix the issue. So I just delt with the glitch.

I have no reason to think the mixer door position changed causing the increased air temp readings after the car is off for a bit. But maybe? I supposed i can manually check the actuator under the hood. Thank you for any feedback.

Waukesha

Well I’m stumped….but not. I found the SM test for the A/C system and followed it to a T and everything pretty much checked out. And Saudade, you were absolutely correct the test should be at 1500RPM. After reviewing the chart with temps, line pressures, and humidity it seems its normal operation to cool the delivery air by about 30F from inlet air. Soooo….if my car is sitting in the sun and its ~100F inside, I can expect the delivery air to start at 70F for a while.

The only weird thing is when I run the first test when the car is cool, the compressor kicks on/off as I expect. But after letting it sit for a while and doing the rest again, the compressor rarely kicks off.

Its seems to me if everything is working properly, a car should cooldown pretty quickly on a hot day while sitting at idle. I’m just curious if anyone’s A/C cools your car quickly on a hot day while sitting at idle. How long does it take for you folks in the south west when its 100F to cool down the cabin??

619rcr

I'm regularly over 100 in AZ. Takes about a minute on my 8th gen accord with freshly replaced compressor, condenser and expansion valve.

As for your car, have you cleaned the condenser and checked the cabin air filter and evaporator for debris?

Waukesha

What you describe for your AC system is what I remember. Thanks for the filter/evaporator advice. The filters were pretty filthy with leaves packed in the bottom (order news ones already). The evaporator fins look good. I vacuumed out the leaves and will put it back together when the filters arrive. The condenser has some smashed fines on the bottom but no obvious blockage. I'll wash it out with a garden hose to be sure. Any other ideas what could cause poor performance when the HP/LP, and vent temps appear to be in spec?

zeta

iTrader: (1)

What you describe above is the exact process that I employ on my CL-S six speed. Mind you, the heat is very, very seldomly used here in FL; however, on those occasional cold mornings this is what I have to do to get warm air.
I thought, this 'glitch' was the result of installing the Mugen cooling mods, back in the day (2005), in preparation for the supercharger install?
Though, here now I finally observe another member describe the same scenario almost 20 years later with their vehicle.

Saudade

Odd you and Zeta have this similar symptom. I'm in SoCal but have never noticed this behavior. Often I need AC during the afternoon and heat in the morning. Mine is a Navi so there are no knobs but I'll try to replicate this over the next few days.

Waukesha

Wait, what?.....is there a super charger available for the Acura TL 3.2L V6 engine?

zeta

iTrader: (1)

It has been about twenty + years, though, there used to be:




As a test, when I drive my automatic CL-S with Navi tomorrow, it also has the Mugen cooling mods, which were installed by the previous owner along with the auto S/C'er kit (since removed).
I am interested in if the 'glitch' heat anomaly presents itself the same way, with that car, as we experience.
I don't recall ever using the heat only the A/C, so I'll report back.

619rcr

My old CLS6 did the same when it was stock. Then again after the 6GA hvac and dash was converted to CLS. I blame the auto climate controls. Before the conversion, the 6GA had manual hvac heater controls (no ambient air sensor, no dash sunlight sensor and no outside air temp sensor). Auto hvac is def one feature I wish the car didn't have.

619rcr

lol, Zeta just likes to tease. I had a SC before too, looks something like this:

Waukesha

That is awesome. I looked at Comptech's website and it looks like those are no longer sold. But I need to get my A/C up to snuff before any other projects.

zeta

iTrader: (1)

At 9am the outside temp was 82f on the gauge cluster, usual A/C / heater temp was set at 72f on center dash read out.

Idle warmed the car to water temp. 160f on the ScanGaugeII.
That's the temp. I usually warm up to before pulling off to drive (old ingrained learned behavior carried over from carbureted cars

At this point I adjusted the heater temp up 10 degrees to 82f, feeling for any noticeable change & felt none after about a minute.

Adjusted upward, in 2 degree increments three more times, pausing in between, to 88f and felt no noticeable change, to my surprise.

Once I hit max. 90f, on the read out, you could hear 'something' change in the dash fan / engine and felt a noticeable temp difference right away.

This push button adjustable auto Navi CL-S does the same thing as the knob adjustable non-Navi CL-S6.

Non-related:

MUGEN thermostat 19301-XGMR-0000

• Operating temperature: 68C (STD.: 76-80C) Full-throttle acceleration temperature: 81C (STD.: 90C)

FAN switch 37760-XK5-00N0

• Enables fan operation at 80 degrees

When driving in stop / go traffic I do notice, in both cars, via the ScanGaugeII that the radiator fans kick on precisely @186f.

Waukesha

Yes! That is exactly what happens in my car. The sound you hear at 90F is the actuator moving the valve to open the hot fluid to the heater core. I replaced that valve thinking it was sticking and moved only when the actuator was at maximum. But nope! The valve was fine so I believe its the signal to the actuator. Not a huge problem, so I left it.

619rcr - If you have a thermometer, I'd love to know the inlet temp and vent time the next time you turn on your AC on a 100F day. According to what I've read the AC should cool the air by 30F, so if its say 110F in your car on a hot day, in theory the vent temp should initially be 80F....but I'm guessing its much less than 30F. It must be to cool the cabin so quickly.

Waukesha

Update: I hooked up the gauges again to measure the time it takes for the HP and LP to equilibrate after shutting off the engine and its been 30minutes and the LP is at 50PSI and the HP is at 100PSI. From my research the pressure should equilibrate in a few minutes so this suggests a bad or plugged expansion valve. Could anything else be cause this slow equilibration? And is this indeed way too slow to equilibrate?

619rcr

Okay, it's 103F out right now. Just tested AC in CLS6 converted 6th gen accord. Takes about 2 minutes to get down from 115 interior temp to 60F vent and stays there. The system was replaced around 2.5 yrs ago and hasn't been serviced since.
In contrast, my 8th gen accord with newly refreshed ac system cools slightly faster. One min to 60F, then peaks at 50F around 3 min.