A/C only cools, not cold at all.

[discman81]

I have a 2007 Tahoe LTZ. And recently the A/C, especially on hot days (90 deg) will never get cold.

A/C is on Max. set to 60 deg and turned all the way up.

I purchased a coolant fill bottle, and when I attach it to the fill port, the pressure ranges from 25 (compressor off?) to roughly 65psi when the compressor is on. It seems that the compressor will turn on, the psi rises all the way to 65ish within 3 seconds, then the compressor immediately kicks off and the psi drops right back to 25. The bottle of refrigerant I purchased comes with its own psi gauge on the top, and it says that if the pressure rises above 55psi and goes into the "red" zone, I am not to add any refrigerant, and to seek professional help.

Thank you all for your help!
Marc

 

[fire730]

With the compressor off and before you even start the truck you should have around 100 psi static pressure. If not you are low on freon.

I'm not too familiar with the "parts" store can and gauge setup so I don't know what the max pressure it shows.

 

[sumo]

You can get a temp gauge and stick it in the vent to see what that temp out of the vent is. It may be best to do a full evac and recharge

 

[Jason_S]

You can get a temp gauge and stick it in the vent to see what that temp out of the vent is. It may be best to do a full evac and recharge

R134a is difficult to get a good reading with using good gages, let alone the junk they put on those cans. Therefore, it is a common and preferred method to do as Sumo recommended. It is not common for most people to be able to do this safely and properly, so you should have the evacuation and recharge done at a shop. If you suspect a leak, then the uv dye can be added at the same time and you can look for the leak if it goes warm again.

EDIT:

You could also try taking a garden hose and carefully spraying out your condenser. It is the radiator looking thing behind your grill. If that is dirty or full of crap, it will affect the effectiveness of your system.

 

[sumo]

R134a is difficult to get a good reading with using good gages, let alone the junk they put on those cans. Therefore, it is a common and preferred method to do as Sumo recommended. It is not common for most people to be able to do this safely and properly, so you should have the evacuation and recharge done at a shop. If you suspect a leak, then the uv dye can be added at the same time and you can look for the leak if it goes warm again.

EDIT:

You could also try taking a garden hose and carefully spraying out your condenser. It is the radiator looking thing behind your grill. If that is dirty or full of crap, it will affect the effectiveness of your system.

Very true about the readings. I work on cars that ac concerns like this all the time. The gauges on the ac machine can show a good reading 80 on the low side and 100 on the high. But when recovering, I'd could recover .13kg when the system calls for .49kg.
Since those gauges on the cans are also inaccurate, add the fact that you don't know how much charge you have in your system, it's hard to judge how much of a charge you need. that's why I recommend a full evac and refill to spec. On top of that almost everyone adds dye so of you do have a leak, you can take a uv light and see where's it's coming from.

 

[discman81]

Thank you all for the input. Finally got back from out of town and had time to investigate and fix. Turns out I was so low on coolant that my compressor wouldn't stay on. Had to jump the sensor with a piece of wire to keep the compressor running and dump in a bottle of coolant. After a few days it is holding the cold temp so I'm guessing it wasn't a leak. Thanks!