Thread: auto A/C

Several items can cause that problem.

Clogged orifice tube. (the filter you heard about)
Bad conpressor
lack or freon or to much freon
high side pressure switch failure

Then the normal fuse, switch, and relay.

What type of vehicle? Did you get a pressure check? If so what was the high and low side pressures?

Originally Posted by moving-target

havent taken it to anyone yet and its a 2001 gmc sierra SLE 1500 never had a recharge that i've known of since my dad bought it in 2000/ 2001

First and foremost check the fuse and relay. The fuse is easy and on that vehicle the ac relay will be the same number as just about ever relay in the vehicle. So just switch one from some where else. If nothing changes move on.

That one actually if im not mistaken has whats called an orifice block. It contains the orifice tube in it. First thing i would do is check the charge on the system. Even if its just 1 or 2 cans. Then see if it starts to cool off. If it does then you know the system is leaking. If thats the case 9 times out of 10 its the charge ports leaking fluid. Most can be replaced without replacing the entire hose.

If that does nothing to the the temp of the air you have to start trouble shooting. With 2 cans the system should begin to cycle. By that i mean the entire front of the compressor will begin to spin instead of just the outer ring.

If it is not spinning you can have 1 of 2 things going on. First the compressor itself may have gone out. Second the high side switch may have gone bad in some way. First check to make sure the connector going to the ac in properly making contact. Simply pull it off and put it back on. While your there see if its cracked or broken. Easy clues to it being bad seeing as they tend to become brittle and do just what your looking for.

Compressors can go out in a few ways. If it was making a shit load of noise then the bearing locked up. If it wasn't then it could have clogged internally. Usually one of the check balls inside the unit freezes in place not allowing freon to move properly. The only way to verify this is with a system pressure test. What happens is the low side will read around 50 lbs and the high side will begin to peg the needle. There is no cure for this aside from replacing the compressor. I've never actually seen that happen on any vehicle aside from gm products.

Once you know the system is cooling down i recommend the freon in a blue can with a polar bear on it. It says 50% cooler on the can and it does work. My camaro and my 99 f150 both have much cooler ac then my wifes brand new ford when i got it.

Also something to look for. Some of the gm modular block like the one you have actually have a seperate ac belt. Wouldn't hurt to take a quick look to verify that and replace it if its gone. Sounds stupid and i try to help without knowing what peoples mechanical abilities are. So good luck and hit me up if you need anything else answered.

ANy mechanic will be able to diagnose an ac problem. Check ac shops though many of them do a free ac check.