Troubleshooting AC

[xrunner123]

Hi all. My air compressor does not turn on and I'd like to know what is the best way to troubleshoot and find out what is wrong.
I'm not too familiar with the ac system, so please excuse me.

I measured the pressure (canistor by the passenger side) with an ac pressure gauge and it reads 50psi when the car is off. I assume that is basically the standing pressure in the whole system and when I turn the car and ac on the compressor should turn on. From there, if it's low on R12 then the low pressure switch should cut it off. Is that correct?

So, either my compressor is shot or the switches are shot?

Are there low and high side pressure switches? If so, can I bypass them real quick to see if the compressor turns on (just to verify that the compressor works?) Maybe the switches are bad?

What is the best way to troubleshoot this? Any ideas?

Appreciate any help
Thanks

 

[CraigT]

I am no expert, but...

Well if you have some pressure that is good. You can try jumpering the low pressure switch on the accumulator and see if the clutch comes on. If that doesn't work, do it again with the clutch connector off and check for 12 volts there. It is located about the 2 o'clock postion very close to the flat bracket that is on the side of the compressor. Also the ECM should send a signal to the fan to turn it on when you put the controls in one of the AC positions.

Try that backyard troubleshooting, Good Luck

 

[FRCEFED6]

if you only have 50psi on the low side static pressure you are very low on freon. static pressure is usually about 100 on both sides when the system is not operating. jump the low pressure switch and check like he said. and get some more freon too. good luck jeremy

 

[xrunner123]

Thanks for the replies. I will work on this over the weekend.

Now, I may be able to get my hands on a 1 lb can of R12. If I can get it, my buddy wants me to be sure that that will be enough (so it doesn't go to waste)- If it's not enough then I'll have to convet to R134 or use Hotshot or the Freeze12 that I'vee been reading about.

Do you think that the 1 lb can will be enough? Does the 50psi standing pressure really tell me anything?

Thanks,

 

[xrunner123]

Here is what I have so far-

I removed the connector to the switch by the canistor on the passenger side and it measures a short. When I turn the car on and turn the AC on inside the car, I measure 0 volts at the connector (connector removed) on the compressor. What does this mean and what else do I do?

I also see a switch near the compressor that has 3 wires- green, green w/stripes and black w/stripes. What do they do?

Thanks,