Hey guys. I'm new here so bear with me. Some might recognize me from .NET

Anyway, i got my 96 Blazer (4.3, 4x4, LT) after it had been sitting for like two years. Needed a tranny, put it in and it runs fine. But getting to the point, we got the air working the other day by putting freon in. We thought we got lucky and it would work fine because we didn't see any leaks and we were using the stuff with the dye so it'd be obvious. Drove it home, no problem air was cold as ice. This was 3 days ago. Today was the first time i'd tried the air since. I couldn't get it to go. When i got it home i found out the clutch isn't engaging, but there's no signs of freon leakage anywhere. I was told it could be a relay but how would i go about testing such things? I'm heading out to the black hills on sunday so any help is much appreciated!

 

Most likely you do have a leak that is not easily visible and that would cause the low pressure switch to not engage the compressor. You could try jumping the switch (it's the one attached to the accumulator) and see if the compressor turns on. If it does engage, your relay is fine, you just need to find the source of the leak and recharge the system.

 

How would i go about jumping the switch?

 

The low pressure switch is on the accumulator (that's where you hooked up your charge kit to add the R134 refrigerant). Disconnect the wiring plug from the switch. You can use a paper clip or similar to jump the wiring plug you pulled off the switch. Start the car and turn on the A/C. If the compressor runs, odds are the electrical system for the A/C is fine, it probably leaked the refrigerant. Do not continue to run the compressor with the switch jumped, if you are low on 134a you could damage the compressor. Their are some other possibilities such as a bad low pressure switch, but unlikely. You mentioned you didn't see any dye leaking out, but you could have a leak in the evaporator which is encased in the firewall and you wouldn't be able to see a leak there.