99 GMC Yukon AC probs

[Britstiva]

My coworker has a 99 GMC Yukon. Her AC isn't blowing cold. We assumed she needed to refill the AC system so she bought a bottle at the auto store.

I connected the pressure gauge before I connected the bottle and it's reading 35. That seems high for the pressure to me, so I didn't try to add any more to the system.

I don't hear the compressor kicking on but then again, I'm not familiar with her vehicle.

Do you guys have any tips??

[shadetree]

What was the ambient temp ? And 35 is mid point /high yes . Rear ac?
Not cooling at all or not at idle ?

[Movin]

Not enough pressure to trigger the clutch cycling switch, dump the stuff in.
If it is rear AC as mentioned you will likely need more than one can.
Safety..if the clutch slows cycling until it stays running do not add anymore.

watch for leaks, none of this stuff is good to just pump out into the air we
breath.

[shadetree]

Any cheap ac gauge reads low side . 35 pnds on low side will start the comp !

[FestYboy]

^ no it won't (at least not a static pressure of 35psi). Jer, you need to check behind the passenger running board for the high and low side AC lines. look for wet spots on the lines near the insulation that is periodicaly wraped on the low side line. also, youe static pressure should be about 10psi ABOVE ambiant temp (70 degrees F = 80psi static line pressure). while running, the low side should not drop below 25psi (this will automaticaly kick the compressor off to cycle the system). also if everything is good, the steady low side pressure should be aprox 35psi on the low side

[Movin]

^^ Yup!

[Britstiva]

Thanks guys! I'll check it out and let you know what I find. It does have rear AC and it wasn't cooling at all.