The air conditioning in my 2007 suburban 6.0 has never seem to work very well. Yesterday I put a meat thermometer in my air vent and drove it around all day. The air would mostly stay around 80° But sometimes would dip down all the way to 60°. A few months ago I did this same test and it would very between 50 and 70°

I can't figure out why it would fluctuate between getting cold and warm. If I had low coolant levels I figured it would simply stay warm all the time and never get cold right?

 

the system may be low on refrigerant, the compressor may be tired...hard to say with the limited information. Does the system short cycle?...compressor cycling on and off frequently?

 

If your compressor is cycling you may be out of Freon or very low on Freon. Check out your in cabin air filter and see if it's plugged up first and go from there bud.

 

07 won't have a cabin filter and that would effect airflow not temperature, need to get pressure readings or check the refrigerant charge

 

I checked the pressures. The pressure seemed fine but maybe a little in the low side so I added a little. The pressure after I added a little was about 46 on the low side and 240 on the high side.

My wife drove it home yesterday on the freeway in the heat of the afternoon (90 to 95 degrees) and said it was fluctuating between 65 and 70 degrees. When she parked it, we left it running in the shade and it got below 60.

Does this tell us anything?

My Hyundai pumps 50 degree air almost no matter what and my neighbors Chevy venture pumps about 45 degree air. Is it possible my system is running properly, it just sucks?

 

the a/c performance test for your truck from you wife's trip are all within parameters.


I see you charge the system yourself. what refrigerant and how do you charge it....stuff you have done may have lowered system performance....air in the system from not pulling a vacuum during before filling....cocktail refrigerant.

 

A/C system should be done by A/C technician only, especially when your system is not properly charged. You will really harm the system and that is costly. JMHO and good luck.
David g.