I drive a 99 chevy blazer and I recently had the engine swapped. Well I noticed the other day that ty A/C was just blowing hot air in my so my first thought was that it was low on R134 so I checked the pressure and it was just fine and then I realized that the compressor starts and then stops. It runs for about 1 to 2 seconds and then stays still for about 5. The pressure fluctuates while it does this. What could this be? please help!

 

I assume you are only checking the low side pressure. What is that reading when the compressor is running?

 

sounds like either incorrect refrigerant charge or the clutch is bad.

 

When the compressor is running it reads really low, but when its off it's really high. Like in the red on the dial. I can't get an accurate reading because it fluctuates too fast.

 

the correct reading is when the compressor is running. Try jumping the green wire to the clutch coil over to the battery. This will engage the compressor so it can suck up the refrigerant.

 

Hi!

I have been having the exact same problem with my blazer, but I figured I was going to have to replace the compressor completely.. You suggest jumping the green wire to the battery, in order for the clutch to engage/stay engaged, right? If yes, at which end of this green wire do I jump to my battery? What's the best way to do this without cutting on the existing wires?

Thanks!!

 

take a 4 ft piece of 14 AWG wire. Strip both ends about 1 1/2". Unplug the coil connector. Place one end of the stripped wire slightly in the hole on the connector that the green wire is in. Plug the connector back in (it wont go in all the way). remove the fuse box lid. wrap the other end of the jumper wire to the stud sticking up that has 12v +. You may have to jimmy the connector on the coil a little to get to get it to engage. After gauge shows good level, remove jumper completely. Compressor should stay running if you have AC on in cab.

 

Where do I hook the other end of the wire? I'm confused.

 

In the fuse box. from what he is saying, you unplug the green/black wired plug from the coil (can't find a pic of that specifically right now), and then wrap around the 12v spike in the fuse box (so one end of wire jammed in the plug where the green wire is, and the other end tied around a 12v lead to the battery, under the lid of the fuse box). You're essentially bypassing any circuitry in the truck and forcing the AC to engage.

Would I have to do this everytime, or once I have done this it should engage whenever I turn on/off the AC?

PS where is the high-pressure port located for guage readings? I know the low presssure is by the canister... can't find the high-pressure service port tho?

Thank you, stlwaco, by the way for the explanation.


-Jerm

 

The only reason it keeps shouting off is because the psi drops and the low psi switch is activated. Once the charge is correct, the compressor will engage when you turn the ac on from inside without a jumper.
Hi psi port is near the low side. Look forward and down. You should see the dust cap
Where in stl are you? Might be able to come show you next time I'm in town... hopefully this weekend