A/C compressor wont run at all. Any ideas?

[Rustbucket1994]

So I go to turn on the air conditioning for the first time this year the other day and I got nothing. The air isnt cold at all. The blower and heat work just fine but no air conditioning at all. I push the knob in for the AC and the little light comes on as it should but no cold air comes out, not even a little cold. It worked fine all last year, never showed any signs of wearing down, it was ice cold all summer.

I checked under the hood and all the connections seem to be good with no corrosion, however the compressor isnt running at all when the AC is on.

Im not sure if the compressor is dead or if its just not getting the signal to turn on from the dash or what.

Anyone have any ideas or experience with this?

Thanks guys

 

[eXcali]

Check the freon pressure. The compressor has a clutch and it wont engage with low/no pressure.

 

[Burns]

I would say that it has leaked down. When mine got low it would run but not like it should.


Do what eXcali suggested and you should find your answer

 

[eXcali]

I would say that it has leaked down. When mine got low it would run but not like it should.


Do what eXcali suggested and you should find your answer

I'd put money on it leaking, if the compressor were to fail the most likely place for it to fail is the bearings on the pulley. This would make all sorts of noise and would easily be noticed.

 

[Burns]

Yes thats almost exactly what happened to mine. It will slowly start to leak out of the pulley side of the compressor. My bearings did not fail tho.

 

[Rustbucket1994]

The compressor doesnt engage at all, or even sound like it is trying to. And it never made a sound last summer, so I have no reason to believe that the bearings are bad. Never saw any leaks or signs of leakage. But if the compressor wont engage due to the freon pressure being too low, that would make sense, I just have to get the pressure tested to be sure. How can I do that?

 

[Alan_V]

Most compressor clutches ground throught their body. Find the connector for the compressor clutch and run B+ to it. Listen for the clutch to click loudly. Simpler? Try swaping the relay.

 

[eXcali]

The compressor doesnt engage at all, or even sound like it is trying to. And it never made a sound last summer, so I have no reason to believe that the bearings are bad. Never saw any leaks or signs of leakage. But if the compressor wont engage due to the freon pressure being too low, that would make sense, I just have to get the pressure tested to be sure. How can I do that?

Go to Autozone and ask one of the workers if they can show you how to use their A/C pressure gauge.
Sometimes if you ask them to test it for you they will decline, but if you ask them to show you then you get it checked for free, don't have to buy a guage and don't have to put the loan a tool on your credit card.

Sometimes you can get lucky and there was just an Oring that got a little dry, using a can of freon/conditioner usually fixes this up. If there is a hole in the system or an Oring is completely shot you have your work ahead of you.... If they check it and it's just real low use the conditioner oil/freon and get it back into good pressure.

 

[gsmaclean]

Disconnect the pressure switch connector from the pressure switch (it's on the passenger side, just in front of the receiver/dryer). Jumper the connector with a paper clip or small piece of wire while the engine is running, and the A/C is turned on.

If the compressor turns on, the problem is that your refrigerant has leaked out, and the pressure switch is doing its job, not allowing the compressor to run when there is no refrigerant (and lubricant, which is suspended in the refrigerant) in the system. Don't let the compressor run this way for more than a few seconds!

If the compressor does NOT turn on when you do this, you've got problems elsewhere - possibly with the compressor clutch.

 

[medievil]

err.. I am sure it was checked, but didn't see any mention or suggestion... There IS a fuse for it under the dash...I know because I had to take my interior light fuse out (Switch is stuck on) and wasn't sure which it was (Stupid of them to not print a diagram on the cover). anyway I had pulled the A/C fuse and didn't re-seat it correctly.. bam, no A/C (Light came on and all, but no kick)

 

[marragtop]

As mentioned by gsmaclean, when you jumper the lower pressure switch, you should then get power to the compressor. If you have power to the compressor and it's still not kicking in, then the problem is within the compressor.

If you don't have power to it, then the problem is electrical and is most likely in front of the low pressure switch. It could be a relay, fuse, wiring, .etc. To further troubleshoot, check to see if you have power at the low pressure switch and then work backwards.

 

[CmdrPopNFresh]

ive seen tons of low pressure switches go bad when sitting and they wont command the clutch to engage.....and if you remove the connector and jump the two pins it will engage the compressor.

if your system has pressure and you can command the clutch to engage id bet my next meal that your low pressure switch is bad. you dont even have to evac the system to replace it either...theres a schrader valve behind it so you can just screw it out and replace it.

 

[zot64]

what if I jumpered the low pressure switch, got nothing. But put 12 v and ground to solinoid and it engaged? Bad relay in black box under hood?

 

[marragtop]

Did you have power to the low pressure switch? If not, then check the AC relay.

 

[zot64]

It was the relay, no power to the pressure switch. Got a new pressure switch (9.00) just for s&g's. Replaced relay with new (12.00) and I now have A/C!!! Now on to the "flare".