So I decided to finally fix my A/C today after not having any for 2 years. I go get a can of DIY refridgerant w/ gauge and come home and find low side port bla bla bla. Anyways, low side is reading 100 PSI after 5 minutes of truck on max A/C. I know there's a clutch that is supposed to kick in on the compressor, I'm not sure if it is or not. Someone told me the clutch may be bad, or the compressor siezed. Anyway to tell?

 

Look at the front of compressor with it running and AC turned on. The pulley willl be turning, but is the center hub of the pulley turning also?

If not, make sure connector to the compressor is plugged in., There is also a plug on the compreeor line near the compressor and one on the drier by the firewall (near the low side port.) These are the high and low pressure switchs. Either one will disable compressor. Also in the PDC, there is a 20 a fuse, front row near battery, second fuse from fender I believe. It is for AC clutch. Check it. There is another plug for the ac clutch. Make sure it is connected and tight. These connectors are prone to getting brittle and breaking and leaving the connection loose.

If all is good, the turn truck off and look at clutch. Do you see reddish dust? See if it smells like something electrcial burned. If so, clutch is bad. If no sign, then ohm it out with a meter and see what it reads.

 

Hub in center of pulley is not turning. Is clutch bad? How do I go about replacing it if it is? It's hell outside.

 

Clutch may or may not be bad. And I was unable to find a new clutch by itself.

Let's take the next steps to verify that it is bad.

Did you check the fuse?
Are all the connectors I mentioned tightly connected?
Do you have access to an ohm meter? (I'll go measure mine so I know how many ohms it should be.)

 

Is this before or after you charged? Your system won't turn on if its to low on refridgerant you can jump it with a paperclip on your low side pressure switch.

 

Once you put some refrigerant in, even if it is not enough, the compressor will cycle on and off until the proper pressure is reached. (I just replaced condensor, compressor, and drier and recharged mine yesterday).

Also, pull clutch connector is necessary and see if there is 12v there. If not, I have killed engine and run a jumper (preferably fused) to the clutch. You should hear it click as the magnet pulls in the clutch plate. If you have 12v present at the conncector, the problem is in the area of the high or low pressure cut off. 100 pounds on low side may be too high - not sure on these - I would have to check. The pressure is also related to the ambient temperature. Been so long since my HVAC license expired, I have forgotten a lot of the numbers.


EDIT: At 90 degrees ambient temperature, the pressure at the low side port shoud read between 50 and 60 psi. High side should read between 215 and 270 psi.

There is also a clutch relay in the PDC for 1999. Not sure about 95 though (but suspect there is one.) May try to swap with another relay and see if it works. If so, the relay is bad.


EDIT II: (From FSM)


(a) If the clutch coil current reading is four amperes or more, the coil is shorted and should be replaced.
(b) If the clutch coil current reading is zero, the coil is open and should be replaced.

 

Not saying your wrong by any means but from what I was taught if the ambient is 90 the system should be equal or close to the same, the high side is good to bout 250 psi 300 is getting scary and after 350 you have a good chance of blowing the valve, low side having 100psi would that you either have to much in the system and its is creating back pressure, or you have a restriction.

 

WOW no AC for two years????????

 

The values I cited were directly form the FSM as well as the info for testing the clutch.

 

If the clutch is not spinning, the system will not take the 134a.