2007 Chevrolet Tahoe Rear ac not blowing cold

Question

I have a 07 chevy tahoe. My front ac blows cold( but it struggles to keep cab cold) and my rear ac is not, only blows lukewarm. I touched my front pipe by the dryer and it was pretty cold (as i am in tx in 97Degree fahrenheit), then went back to the pipe where my rear expansion valve are and it was lukewarm (not cold or not too hot.) As i was touching the rear ac pipe i felt that some cool air was escaping from the rubber seal that goes around the expansion valve, plastic is really worn out and some pieces missing would tgat be a issue? any help is appreciated. I was thinking either my expansion valve could be clogged up? Want to make sure before i start disassembling. Thanks !!

Answer 1

This system needs to have manifold gages hooked up to it. This will give an indication whether it's low on refrigerant or has a bad expansion valve or compressor or any combination of these. Without doing this, guesses can go on all day. An experienced tech can pretty much give a reliable diagnosis with the gage readings. It is automatic to also check for leaks. From the description, my guess would be a bad expansion valve plus a possibility of low refrigerant. But you must start with the gages.

Answer 2

All vehicle ac systems will suffer the #1 problem; a leak or leaks after several years of reliable cooling. System configuration demands aluminum parts to save on weight and aluminum is inherently soft, work hardened after rough road conditions vibrate thru suspension. A big mistake is running to auto stores for the refill kit containing sealer in hopes of an inexpensive repair from a can, more often than not refilling doesn't fix a leaking system. Sealer contaminates and may lead to a more expensive repair requiring rebuilding; replacing compressor, condenser coil, thermal expansion valve(s), receiver/accumulator/drier, etc. Remove both service valve caps and check for the presence of dye (greenish yellow) and oil. GM installed dye for easier leak detection of sealed systems. If you see dye in the service ports, buy an inexpensive uv blacklight and inspect the entire system, looking for dye marking the leak site. Then determine whether you can make repairs requiring parts and new O-rings for every part replaced. Use the blacklight in shade, indoors or at night to allow dye to glow from uv illumination. Shine it at dye in service ports to see how bright it is. Refrigerant, oil and dye circulate continuously throughout a system and when a leak occurs, invisible refrigerant, oil and dye leave with oil and dye leaving markers. Service valves wear out and may leak (caps help with sealing), fittings crack, crimped fittings leak, punctures can occur in the condenser coil, aluminum tubing cracks, etc. Compressors and thermal expansion valves rarely fail; losing refrigerant means less to zero cooling and enough refrigerant loss triggers the pressure senor to send a disable signal to the ecm to prevent compressor operation; oil won't return to lube the compressor, resulting in immediate damage. Find and fix the leak and restoration of factory cooling can return. Losing about half its refrigerant may allow compressor operation but little to zero cooling. Refrigeration gauges are a must whether commercial or diy repairs. Gauges and electric vacuum pumps may be free loaners from Autozone or other auto stores.