Problem:
My A/C always blows hotter on the drivers side than the passenger side. I thought that this problem was probably related to the drivers side actuator/temperature door, but I have disconnected it and moved it by hand and the drivers side is still warmer than the passenger side.

After initial startup & while driving down the highway (after I leave work in the afernoon) the passenger side blows cold, but not ICE cold and the drivers side is usually pretty warm. When I come to some stop lights (after ~ 25 min of driving) or slow down becasue of traffic both sides of the AC get colder. If I sit at a stop light for 30 sec to a minute, the passenger side of the AC gets freezing and the driver's side gets cold but not quite as cold as the passenger side.

Also, the drivers side feels more humid than the passenger side (it obviously would be if there is not as much cooling) almost like air is coming from straight outside out the driver's vents.

On humid mornings, I can tell that some (not much) cold air is blowing out the defroster vents because of condensation on the outside of the windshield.

Here's a basic rundown of things I have looked at so far:

Compressor pressures seem to be good. High/low side pressures match reasonably well with diagnostic charts.

Condenser does not have trash on it.

Cooling fans come on.

Driver's side actuator moves as you turn the temperature ****.

NO HVAC codes set.

I'm trying to avoid ripping into the dash to look at the other doors and seals, but I don't know what else to look at.

Anyone have any suggestions on where to look next? Anyone have a similar experience. Do the above symptomps indicate a low refrigerant charge or a bad compressor?

TIA for any help!


[Modified by MrPDJ, 5:00 PM 5/12/2004]


[Modified by MrPDJ, 5:01 PM 5/12/2004]

 

Before you tear into the dash make sure your HVAC system is properly charged. Even though it looks ok on gauges if oyu have never had the system serviced it could be slightly low causing your problems. Daul zone HVAC systems are sensetive to the refrigerant charge. I would start be evacuating and recharging the system to the proper level.

 

Could be a faulty high pressure cutout switch, air in the system, or both. Check pressures and clutch operation at higher (>2000rpm) engine speeds. If either one of these turn out to be the culprit, you're going to end up going the route suggested above, anyway. Good luck.

 

How could the system be slightly low with out having a leak? If it is low, find the leak and repair it. Then evacuate and recharge to factory spec.

 

Without getting to involved, the molucules in 134a refrigerant are small enough that they will seep through the rubber lines over time. It is a very small seepage but .20lbs can make a diffrence.

 

I have a hard time believeing that the manufacturer and A/C industry would not know this and change the material with which the hoses are made from. I think they have.

 

The manufacturers know this. It is a small seep,say you have 3 year old car and have never serviced the a/c. It's normal to be a few tenths of a pound low.

 

Don't the manufacturers use a barrier type hose now to prevent leakage through the hose's lining? I agree with you that R134A has a smaller molecule and will leak at a higher rate than R12, but they both would leak through std. rubber hose. I don't think the EPA would allow the use of these inadequate hoses if they are prone to leak. Seems shade tree to me.

 

Your correct about the barrier type hoses and the mighty hand of the EPA,however with all the O-rings,pressure switches and moving parts in the compressor an average vehicle will loose some refrigerant over time. Hvac systems have improved dramaticlly over the years but in my experience they all seam to have very minor refrigerant seepage and some are even under or overcharged from the factory.

 

Well, it's a good thing that when I stopped working for a certain company, rhymes with plane, I had a good stock pile of Refridgerant to cover any vehicle, old and new.

 

UPDATE!

Well, before I started ripping into the dash, I thought that I'd try to add a little bit of R134 to see if it made a difference. I just added a small ammount and it made a world of difference!! I've got cold air on both sides now and it is the same temperature at all speeds! The system must be sensitive to charge level.

I suppose that i need to take it in and have the system leak tested to find out why the refrigerant was low in the first place. I just bought the car back in Jaunuary (98 6 spd), so I don't know if the previous owner had problems with the AC or not.

Thanks for the advice and saving me a trip underneath the dash! :D