air conditioning issue 2005 denali XL

[FreeIndeed]

HI guys. I had the dealer recharge my AC about a month ago and now the front isn;t blowing any cold air and the back was still blowing cold but now isn't. The dealer said I have a leak on the long lines that run to the back and it was 850 to replace plus another 600 if something or other was rusted out.

Today I bought a can of acprocold and was going to try recharging it. THey have you connect the can to the low pressure port and then read the gauge once the compressor comes on. Well, the compressor cycles on and off and there's a hissing sound in-between. THe pressure, which I assumed would be low, was actually reading high on their gauge (and yes, I did set it to account for the ambient temperature.)

Does anyo0ne have a clue what my problem could be? I'd expect the pressure to be low if the leak was the problem, but it's not. I'd hate to replace the lines if they aren't the problem.

 

[01ssreda4]

What was the exact pressures it was reading. You need to account for pressure difference. When an ac system is not running (compressor off) the pressures equalize. The reason the low goes low and the high goes high is because of the compressor pumping. If the compressor is off, high and low will read identical, probably around 70 pounds from my experience. Once it cuts on, you should start seeing double that on the high side and half that on the low side.

 

[FreeIndeed]

When the compressor kicked out it would fall - I can't remember to where, then when the compressor kicked in it would raise to maybe 65-70 and then repeat. They red zone on the acprocold gage starts at about 50psi.

 

[01ssreda4]

The red zone only applies when the compressor is running. If there is adequate freon, a good compressor can pump the low side down. A weak compressor cannot and youll get higher then normal pressures. But if the compressor is cycling then yes it will be high because it doesnt have time to work.

 

[BigMike636]

My wife has a 2005 Yukon XL and this year, her A/C wouldn't work. I tried charging it, but it was the leak that they mentioned to you going to the back evaporator coil. I wound up plugging it off and charging it up. Using just the front evaporator has been working well.

 

[Yukon2000xl]

If you are missing freon then it's pointless to keep charging it unless you fix the leak


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