Please help me diagnose an A/C problem

[ShadetreeSHOguy]

Hey guys, among quite a few other problems w/my SHO, I have an a/c problem that has had my brain itching for a while. I have the dual gauge a/c thing(dont know what you call it, lol) at the dealership i work at and i figured id hook it up. The low side of the a/c is holding steady at 40 psi(which i was told is where it's supposed to be). Now the high side is reading at 0, no pressure at all. The compressor isnt kicking on at all either, so where should i start with replacing stuff on my a/c system? Thanks in advance for the help :wave:

 

[The Dude]

It should probably read higher than 40psi. If the car is sitting and it's hot it will read much higher than that. When the compressor is running and the system is in use it's then that it should be around 40, actually I'm not sure what the regular operating psi is. It's in the green on my gauge. You'll have to override the psi shutoff switch to get the compressor to spin, once you do that I'll bet the psi drops and you'll need to fill it.

 

[Ishodu]

With the compressor not running both sides should be the same. The low side should be 25-40 when the compressor is running, not just a static pressure. I think you should try to test it again.

 

[ShadetreeSHOguy]

That's the thing, i cant get the compressor to spin at all. How do i get the compressor to kick on, is there some sort of sensor that's gone bad, do i need to override something?

 

[naval-avi8or]

Could be one of the following:

Cycling switch (disconnect and short contacts if clutch engages low freon)
CCRM (two wires that can be checked one from cycling switch and one to clutch)
Electric clutch/airgap (check for 12vdc at clutch)

 

[Ishodu]

To get the compressor to run you can, as long as there is nothing else wrong with the system other than low pressure, you can take the plug off the low pressure switch and jumper it. Its located beside the coolant reservoir on a MTX. You will have to reach down a bit. If you search someone has posted pics of it before.