AC/Vent Temp Difference between drivers/passenger sides

[wormwood1978]

2008 Trailblazer. I recently recharged the AC system. Anyhow, I didn't think it worked very good until I checked the passenger side vents which were good.

So with the AC on or just straight vent without the AC button pressed, I get roughly 10-15 degrees colder on the passenger side two vents then I do with the drivers side vents or the backseat vents. What is probably going on here?

80 degrees outside, With the AC on I get roughly 50-54 degrees on the passenger side, 65 on the drivers side. With the AC off but just working off the fan, I get about 65 on the passenger side, 75 on the drivers side. If I move either of the temp levers from cold to hot, the temp increases so there is temp regulation.

 

[gmcman]

Sounds like the either the temp or blend mode actuator is failing. .I honestly can't remember which one affects the left and right.

 

[Mooseman]

Try doing a recalibration to the HVAC system by pulling the HVAC-B fuse for a few seconds, put it back, turn the key to ignition but don't start the engine or touch any of the controls. Let it do its thing for a couple of minutes and try it out. If it's still the same, probably your driver side temp actuator is dead. Go to this link for the diagram of which actuator is which with part numbers:
hvac actuators and dash removal

 

[wormwood1978]

Pulling the fuse did not do anything but thanks for the suggestion.

I purchased a AC manifold gauge which told me the high and low pressures were both low even though I added refrigerant about a month ago (temporarily fixed not cold enough AC). So it looks like I have a leak somewhere. I just finished adding 12oz of 134a and a small can of AC stop leak & detector. Pressure is a lot better now and the car AC is fairly cold. Hopefully it stays that way, if not, hope the dye will tell me where the leak is.

Also, I read that a symptom of low refrigerant can be an unequal balance of cold air out the vents. Since adding more refrigerant, I'm getting the same cold on both vent sides.

 

[Mooseman]

I guess it's possible but either way.. you'll have to fix that leak. If you have a UV light, you can look for the leaking dye. If not, may require a leak detector.

Btw, those stop leaks are not recommended. In contact with air, they can make a real mess of things, called the Black Death.

 

[Blckshdw]

FWIW, I had a leak in my AC system recently as well. Ran some UV dye through and checked with a UV flashlight, couldn't find any trace of dye. Turns out the accumulator had some sort of internal failure which resulted in a leak, but no dye was visible.

Only clue was that there was an audible hissing sound when I added refrigerant, and also when I pulled a vacuum. Replaced that last week, and have been in good shape ever since.

 

[DAlastDON]

Safe to say the desiccant bag was absorbing the dye?

 

[wormwood1978]

So far so good since adding some more 134a and a small bottle of stop leak and dye. The dye is red, non-UV. So far the AC is holding strong and no visible dye yet. Time will tell. If the problem comes back, I will add another can of 134a that contains uv dye and see what I can see. Fingers crossed

 

[wormwood1978]

Back to low freon again based on the AC no longer cooling very well and the readings I was getting off the manifold gauge set. So this time I added yet another can of 134a but also some UV dye. Everything looks good under the hood but I do have quite a bit of dye that appears to be coming out of the condenser. Looks like if I want to have AC, the condenser will need replacing. It looks to be a little expensive to have a shop do the work or I can do the work for around $100. I will start reading up of the later option and see if this is within my capabilities.

 

[Mooseman]

It shouldn't be too difficult. You would need a vacuum pump to pull a vacuum and evacuate all the air and confirm the leak is fixed.

If you get a replacement evaporator, either get an ACDelco or check on the number of fin rows. Most of the aftermarket ones have less rows and are less efficient. Also check with the dealer. Some parts are some times cheaper there.