I bought this in early April 2023. It was impressively clean inside and out. It's actually a Suburban. I thought I did a great job checking everything before I bought it, but I missed some important things. During my inspection the weather was very mild, there was no need to use the A/C or the heat. After purchasing it the weather got warm outside, I went to use the A/C, it didn't work. I checked under the hood, the clutch for the A/C did not engage. Simple enough I thought, it just must need more R-134. I added some and brought the pressure up to 32 PSI, within the green range. The clutch did not engage, I thought it should have. So, I started thinking. Then I realized I never checked the heat, so I tried it. It was only luke warm. So, I turned all the way up to 90, still luke warm.

I've been working on my cars and family and friend's cars for 30+ years and have had great successes.

But in this case, I need some help.

Pls let me know what you think.

John

 

If you’re still needing an answer…

The weak point for the AC on the suburban/Tahoe models with rear climate control are the lines that run behind the right rear fender liner and the rear evaporator/expansion valve union. Dirt/debris collects in these areas and eventually rubs through the lines or causes corrosion to separate the expansion valve and lines.

If the system has already had leak dye added to it, look under the right rear of the body, above the tail pipe to see the expansion valve and above the rear cradle on the inside of the right tire to see the lines.

Leaks will be identified by a greenish-yellow film (if dye is present). If no dye is present, leaks can still be identified by the accumulation of dirt (often damp in appearance) in the area of the leak.

Kits to repair or block off the lines are available. If the expansion valve is leaking, plan to replace the evaporator and valve - the screws that hold them together are often too corroded to remove.

As for heat, make sure the coolant level is at or just above the full cold mark on the surge tank. Top off as necessary and run the front and rear blowers/heat on high for at least 5 minutes to bleed the cores.

Also check the cabin air filter - this is often overlooked and they’ll restrict air flow when plugged. Remove the glove box and the filter door should be visible.