A/C compressor not kicking in

XR7inWI

Registered User
I was checking out my air conditioning tonight, originally thinking it would not blow cool air because it needed to be recharged. However, I did notice that the compressor does not kick in when I turn on the air. Obviously, if the compressor doesn't kick in I ain't gonna get cold air from the vents. :rolleyes: I pulled the electrical connector off the compressor, started the car, turned on the air (to MAX) then checked for voltage at the plug. I only got .040 volts DC. Seems rather low to me, what should I have there for voltage? I checked all fuses and all are good. Can anyone here point me in the right direction for what to check next, or does anyone have any ideas what might be the cause of the A/C compressor not kicking in?

Thanx in advance to all who can offer some advice here.
 
If the freon is low, then it will not let the compressor kick on to prevent damage to the compressor. There is a pressure switch on the accumulator that does this. However if it is not low then sometime you can take a screw driver and tap on the clutch on the compressor and most of the time it will go ahead and engage, ive done this on several different vehicles. But like i said earlier, if it is low then it wont kick in no matter what.


Derek
 
re-air

It needs to be recharged when its low on freon. If your clutch won't pull in and engage on your compresser you can jumper the wire over to see if your compresser kicks on If it kicks on your compresser is good. Its a safety thing when your freon is low it won't come on. It will need to be recharged. If it is r-12 it will cost you. Search on changeing it over to r-134 Best of luck!!
 
Hey thanx for the replies. I kind of thought that may be the case (compressor would not kick in if freon level/pressure was too low) but was not sure. I will try jumping the compressor to see if the clutch engages. If the clutch does engage, I will see about getting it charged or converting to r-134.
 
I would also check the pressure that you are getting from the High Pressure and Low Pressure.

Low pressure should usually represent the ambient temp. If is 96 degrees, then the pressure is 96 PSI. High should be somewhere in the 190's to 220's.

Now, if the pressure is the same on both sides. 40PSI and 40PSI(just throwing numbers out there) then the compressor is bad.

My compressor is constantly engaged, I think, and the pressures are the same. When the car is moving the AC is cold...very cold. I looked to see what a new compressor was going to cost, even with my discount, 203 someodd dollars. Just giving you a heads up.

Stephen
 
89SCK@t said:
Low pressure should usually represent the ambient temp. If is 96 degrees, then the pressure is 96 PSI. High should be somewhere in the 190's to 220's.
Ummm... low side pressure in a running system should cycle in the mid to high 20s. 96 psi on the low side is cause for concern.

89SCK@t said:
Now, if the pressure is the same on both sides. 40PSI and 40PSI(just throwing numbers out there) then the compressor is bad.

My compressor is constantly engaged, I think, and the pressures are the same. When the car is moving the AC is cold...very cold. I looked to see what a new compressor was going to cost, even with my discount, 203 someodd dollars. Just giving you a heads up.

Stephen
If you have cooling with the car moving, then something is wrong with the way you are taking the measurements. Make sure the guage valves are fully closed and check again. ;) Either that or get a different set of guages as it is thermodynamically impossible for the pressures to be the same and to have cooling.
 
Ummm... low side pressure in a running system should cycle in the mid to high 20s. 96 psi on the low side is cause for concern.

I forgot to say when the car and system is off...I knew I forgot something.

If you have cooling with the car moving, then something is wrong with the way you are taking the measurements. Make sure the guage valves are fully closed and check again. Either that or get a different set of guages as it is thermodynamically impossible for the pressures to be the same and to have cooling.

I had it hooked up to a system that vaccuum's and recharges A/C systems at Big 10. I asked the mechanic that was there what the same pressures mean and he said that the system (A/C) must be running open. My A/C is constantly engaged and my pressures are the same. That is why I said that the individual that started this thread should look out for that.
 
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