I'm having a very frustrating issue with my '04 TSX (no nav). The heater intermittently blows ice cold air when at stop lights (temp set to 74). Living in Chicago, this becomes an annoying issue in the winter. Problem appears in both Auto and manual modes.

Engine is warm and radiator temperature gauge is at the normal level. Car has been into the dealer 3 times for the issue (still under warranty). Being intermittent, surprise surprise the dealer can't reproduce it and won't do anything about it. They've checked the computer and coolant system, claiming everything is functioning properly.

Read other posts about HVAC issues (mainly AC) in the TSX. Any ideas on this one? Thanks!

 

Have you verified that your coolant is full?

You may not be pushing enough coolant through the heat exchanger to heat the air at idle. Also you can access the hvac instrumentation yourself (see the easter egg thread for info). Check to see if the temperature drops off at idle.

I have not been having any trouble with my 04 during this wonderful Chicago weather.

Just curious, what dealership have you been taking the car to? Welcome to the board.

 

Thanks for the welcome Mskierki. I bought the car at Napleton Acura in Elmhurst, but after I moved to the western 'burbs I started having it serviced at Continental Acura in Naperville mainly for convenience.

When this problem started a few months back, the coolant was the first thing I checked. It looked to be just below the minimum line in the reserve tank. I added a few cups of the pre-mixed 50/50 coolant, but the problem kept happening. I asked Continental to test the coolant system for leaks and they claimed it passed.

I've had some issues with Continental not fixing problems on the first try, but they've had 3 chances with this problem...

 

I don't have a manual for the TSX, but other cars I have owned use a vacuum controlled valve to mix hot and cold air for the proper temperature. It sounds like that valve is stuck or frozen in the wrong position, and this should be a simple diagnostic for dealer to verify. Cold sucks ... especially in Chicago this time of year.

 

Checked out the HVAC easter egg and did a quick testing last night. (Outside air temperature was 15F during the test.) Heater was malfunctioning as described above and I got the following readings:

1) In car temp = 04
2) Ambient temp = A6
3) Solar sensor = 01
4) Engine coolant temp = leveled off around 85
5) Evaporator temp = A4-A6
6) Driver's air mix = 99
7) Passenger mix = 99
8) Speed = varried
9) Vent air out temp = 99

Based on that, it looks to me the HVAC computer/sensor system is working. nbtx, I think you are on to something with the vacuum valve not opening or closing. Problem is worse when the air temperature is below freezing.

I've also noticed the problem goes away after the car is driven for more than 30 minutes...

 

You get warm air when you're not idling right? If you get warm air at least some of the time then that flap dealy is moving. It sounds like you've got air in the coolant to me.

 

Well that occurred to me also ...
However, look at items 6,7,and 9 of the readouts. 6 and 7 show full heat to the vents, but 9 shows 99 degrees C output which is not possible if cold air is coming out. This tells me there is a bad vent temperature sensor, a wiring/connector problem, or a bad controller. I say try to find another dealer - isn't there one in Westmont?

 

Right LukeaTron, warm air when you are on the throttle. Cold air at idle. Going to take it up to Elmhurst on Monday.

 

Problem solved after a few more trips to Continental. Faulty thermostat was to blame.

I tracked the readings from the HVAC diagnostics for about two weeks and logged the results. That allowed the technician to narrow it down to the thermostat.

Need to give credit to the service manager Mike who did an excellent job making sure the problem got fixed.

 

According to post #1, a themostat would have been the last place I would have looked. You said
the temperature gauge was reading normal. That makes me wonder where in the coolant flow path the temperature sensor is, and why no warm/hot coolant didn't get to the heater core.
???

 

Technician wrote on work order "thermostat randomly sticking in the open position". Service manager said this was the first thermostat he could remember replacing in a TSX. Strange, but at least I have heat now.