Model: GRAND PRIX
Engine Size: 3.8L
Refrigerant Type: 134A
I was on here about a month ago looking for some information. At the beginning of summer my a/c was very poor. Diagnosed down to a poor compressor. Replaced the compressor/drier/orifice tube and filled to spec. Pressures running perfectly within spec. Although, now that we are really into the dog days of summer, I'm still not pleased with the A/C performance. If the ambient temperature is below 80-85 degrees the ac works pretty good going down the road. What I noticed is, the other day we had a hott one, 95F. Going down the interstate @ 70mph the ac was on high and this kept the car comfortable. However, when I go into city limits and found myself cruising/idling through traffic...the AC may as well have been turned off because the air was blowing "cool" @ best. I also noticed that the passenger side vents were blowing quite a bit lower temperature then the drivers side. So my question is to you guys, what else do you think I may be looking @ here. The cooling fans are running, but it doesn't look to me like they're working very hard (in comparison to other vehicles I've seen/heard)(is this normal?). Is it possible I have a poor condenser? I thought I would look here for some insight, possibly of common issues or how you would suggest I approach/diagnose this issue. Any information you could provide will be of great help. Let me know if there is any further information I can provide. Thanks!!
Cold on one side of a GM can mean the charge is low. You may have a leak. I think it has a variable displacement compressor so it's not going to do the typical CCOT thing of cycling on and off rapidly when undercharged. Check the pressures again.
Edited: Wed June 15, 2011 at 2:43 PM by mk378
Edited: Wed June 15, 2011 at 2:42 PM by mk378
Ill double check the pressures this weekend. Any thoughts as to what else could cause these symptoms?
I'm not a car guy so I can't testify to the difference in vent temps.
But yeah, MK is right, double check your pressures, make sure you still have your charge. Also check the condition of your condenser, make sure it's not insanely dirty or plugged up. The fact that AC works when you're driving and there's good airflow, and then goes to shit when there isn't, kind of points to the condenser. Or the fan that's supposed to blow air over the condenser.
The condenser could possibly be feeding a liquid/gas mixture to the orifice instead of subcooled liquid, since it can't keep up. Which definitely would decrease evaporator efficiency.
If the liquid coming from the condenser isn't subcooled, it could be prone to flashing off prematurely while it runs through a hot engine bay, which could lead to random cold spots in the piping... I don't know jack about vent airflow/etc in vehicles, but that could be an explanation to one side being colder than the other.
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