Automotive Air Conditioning Information Forum (Archives)

markf1971 on Thu July 03, 2014 4:44 PM

Year: 1999
Make: Chevrolet
Model: Suburban
Engine Size: 5.7
Refrigerant Type: R134a
Ambient Temp: 90
Pressure Low: 30
Pressure High: 220
Country of Origin: United States

I have a 99 Burb that I bought 6 months ago. I just got around to checking out why the AC didn't work. It had an obvious leak where the hose connects to the compressor. I cleaned up the outside, replaced the seals (washer w/rubber), pulled a vacuum on the system and it held (YESSS!). I charged up the system and it cools pretty good in all the front vents. However, the rear vents feel like ambient air temperature. My first guess was that perhaps the expansion valve for the rear evaporator core was stuck and won't open. Does anybody have any experience with this happening?

Also, the AC compressor never cuts off. I have been cycling it off every few minutes via the "AC" button on the dash to keep things from freezing up. Any ideas on that?

Thanks!

Jag987 on Thu July 03, 2014 9:30 PM

How much refrigerant was added? The low side appears a little low to me. If it is low, that child explain why the rear is not working. Why are you worried about it freezing? If the low side gets much lower, the compressor will cycle on its own.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

Dougflas on Thu July 03, 2014 9:38 PM

Easiest thing for a DYI 'er is to get under the vehicle and feel the lines feeding the rear evap. Some rear evap vehicles have a solenoid to shut down the refrigerant flow when only front is requested. Check to see if that is your case and see if there is a control voltage there. Also, this would not be the first vehicle that had the rear disabled so check that out also.

crracer on Thu July 03, 2014 11:44 PM

The burb should have 3 lbs. 8 oz of refrigerant added. I just charged a 99 Yukon with rear air, I set both front and rear on high as it filled, 2 lbs. 12 oz in the Yukon's case though, but that's because it wasn't an XL, such as the burb.