Hi i have a gmc 1500 the ac was blowing slightly cool but by far not working correct. I went to oreily's bought some freon. Checked the level it was low so charged it to 45 psi. I noticed a slight change but its still not cold. Compressor is working or it would not be cool. Also the air coming out feels kinda damp & humid. Can somebody please help!!!!!!!

 

How many ounces did you add? Did you empty the can? If you haven't, add more. I don't have a firsthand experience with cans but I heard the gauge is grossly inaccurate. I wouldn't add another can without connecting real gauges to both hi and lo ports.

 

does the compressor clutch turn on? you will hear a click and see the front piece of the compressor start spinning when a/c or the defrost is turned on. and the data tag by the radiator support will say how many pounds of r-134a u need. and call around see if any auto parts stores have a a/c gauge for loan, they usually have loaner stuff. if the compressor is turning on i wouldnt add any, if you think theirs a leak you need to bring it to the shop so they can add dye and fix the leak.

 

Its strange the compressor is kicking on and the air is slightly cool. I bought one of the cans that have the gauge built on. It should cool if it has enough freon to kick the compressor on? ughhh just lost with this one. Havent heard good things about the ac shops around here either!

 

A/C is not really DIY work unless you have training and experience. You said you charged it to 45psi... now you may have overcharged the system. Overcharged is as bad as undercharged for cooling performance. Where are you located? Surely there is a GM dealership in your area. They have trained and certified techs that do A/C work regularly. They will have the proper equipment to diagnose your concern.
Hope this helps ya,
Billy

 

did you purge the line when you hooked up the suction as you connected it? sounds like it is slightly short,get the truck to operating temps hook the can and hose up to the suction bleed it out as your connecting it to purge the hose of air,close th hood if you can and add GAS only do not flip the can don't want liquid going into the compressor...get the engine up to 2000 rpm sound wise 55MPH and you'll see the suction drop on the guage tweek the freon in and you'll feel the vent discharge start to drop in temp and then it should get ice cold shut the can off disconnect and take it for a ride...s much as the fan when parked pulls air over the radiator and condenser 55MPH is the design factor when charging.i know the hose they giv is short to close the hood or be sitting in the cab tweeking freon and feeling the temps a longer hose and brass union will allow you to solve this problem NOTE on purging with freon if you don't you push the air into the system and it mixes with the exsisting freon and takes away effeciantcy during the hot days..as long as you purge and keep the system positive a revac isn't needed...check out Automotive Air Conditioning Information Server: Home totaly auto ac forum if more help is needed..good luck

 

Your fan speed switch as well as temperature control can both be recalibrated using a tech2 at a dealership if they don't recalibrate correctly your blower motor resistor is also a simple change after that i would take it somewhere to evac your system then replace your orifice tube for cheap insurance.. its only a dollar at any auto parts store but if you find metal shavings in it your compressor is probably about to give out.. some lube places have the equipment to refill the exact amount required and do it right for a small charge