Ok...I I just reinstalled the A/C back into my Galant. I haven't really been driving the car since I installed it..and just checked if the a/c is working while the car is on idle and it cycles and blows super cold air perfectly.

Well today I decide to take a quick drive to the grocery story and noticed shortly after leaving the house it felt like the a/c compressor was constantly cutting on and off in 2-3 second intervals. Well got to the grocery store and did my shopping and started the car and put on the a/c and it was running normally, but as soon I started getting the car rolling it would start cutting on and off again.

I do remember the something like this happening right before the previous compressor went out years ago prior to me reinstalling the a/c back in the car a few days ago.

Any ides?

 

Do you have access to gauges and post what the low/high sides are reading?

 

A great suggestion .. if you only have access to the low side it should read between 35-45 psi. You could just buy a can of R134 with a cheap gauge for the low side and plug it in with the A/C running on max cool. Clutch cycling is usually a problem with pressure as the previous poster mentioned.

 

That one of the things I don't have in my garage. I will see if I can get some readings tomorrow and post. What readings should I be getting?

 

It depends on the temp but the low side should be around 35-40 psi and the high around 180-200 psi.

 

Ok...got bought a low side gauge and I am getting 42 psi at idle.

Now when I rev the motor past 2k the compressor clutch cuts off and tried to engage again like I stated. When the car idles again...the clutch engages and the compressor operates normally.

Is is possible my compressor clutch is the problem?

 

Whats the low side pressure when you rev it to 2k?

 

If the clutch is engaging at all it probably isn't the problem. Measuring the high side is something best left to the shop or people unlike me with the proper tools.

It sounds like the problem is that the freon isn't transferring/compressing properly from one side to the other. It could be a restriction in the condenser or somewhere else in the system. Is the electric fan coming on behind the radiator ? If not that might be the problem too. If it is bad the system will shut down at high rpms.

This might help your understanding of the system:

The compressor puts the refrigerant under pressure and sends it to the condensing coils. In your car, these coils are generally in front of the radiator. Compressing a gas makes it quite hot. In the condenser, this added heat and the heat the refrigerant picked up in the evaporator is expelled to the air flowing across it from outside the car. When the refrigerant is cooled to its saturation temperature, it will change phase from a gas back into a liquid (this gives off a bundle of heat known as the "latent heat of vaporization"). The liquid then passes through the expansion valve to the evaporator, the coils inside of your car, where it loses pressure that was added to it in the compressor. This causes some of the liquid to change to a low-pressure gas as it cools the remaining liquid. This two-phase mixture enters the evaporator, and the liquid portion of the refrigerant absorbs the heat from the air across the coil and evaporates. Your car's blower circulates air across the cold evaporator and into the interior. The refrigerant goes back through the cycle again and again.

Hope I've helped. Troubleshooting A/C is a PIA as most mechanics will admit to. I'm glad mine was just the stupid clutch assy.

 

Thanks Brokedad for the reply and the useful info...I appreciate that!

The fan kicks one when I turn on the A/C...and it stays on till the a/c clutch disengages, but will always kick back on when the clutch engages.

So its another possibility that there is possibly a restriction in the a/c system?

I may have to visit a friend that runs his own auto repair shop and see what he can diagnose for me and I believe has the proper a/c diagnostic equipment.

 

I know I am a bit ignorant when it comes to A/C systems..but when I rev beyound 2k rpms the pressure reaches 65 psi. Is that normal?