guys-- happy new year. I was working on the car prepping for a move to the south and changed out a new alternator and starter. Worked well and also did a drain and refill of the radiator. As I was circulating the new radiator coolant I noticed that my AC compressor wasn't turning on (2003 SE, manual AC controls)- even though the AC light was on. I tried the full max AC and the AC compressor would not engage.

I have the the following questions. The car just hit 160K-- and it is the original AC compressor-- has anyone had their changed because of failure? Another question is this, I checked the low and high side of the freon pressure and there is NO pressure (seems like the pressure is all gone since last summer) when the AC was working very well.

This is my second question: is there a way to diagnose if the AC Compressor is good and would the compressor engage if there is no freon pressure in the system? is that something the car does to protect the compressor?
Any suggestions / thoughts most appreciated. Happy new year!

 

clutch in the compressor may be no good if its not kicking in

 

If u have no refrigerant then the low pressure switch will keep the compressor from engaging. I've never checked the wiring on the maxima compressor, but u can jump the connection at the compressor and make it engage. But first things first, I'd get a $10 can of freon and put it in. If its not engaging bc low pressure, this will make it start cycling. But if ur low on freon, u have a leak and it'll prob just leak out again. Some cars only leak enough that one can very summer does the trick. Try to get ur hands on a vacuum pump and pump the system down, see if it'll hold vacuum or if its leaking

 

thanks-- it helps to confirm that if there is no refrigerant in the system the compressor will not engage even if the AC button is pressed. I think the system is drained but I am not sure if the car is 10 years old and 160K into it, that the refrigerant leaks a bit each year but yes, I will give it a try. I did find steps on jumping the compressor and seeing if that works.

 

If you can verify that the system is completely out of refrigerant and the a/c ran fine in the last year one would think that you have suddenly developed a substantial leak. I have been retired from the trade for some time but the first place I would look is at the bottom of the condensor coil that is in front of the rad. If you see oil staining there is a good chance that you have a leak. Frequently these coils corrode from the inside due to acids that build up in the system from improper service work. Certain vehicles use to be more prone to this due to improper procedures at the factory. Chrysler mini-vans use to be famous for this. The only repair if this is the problem is to install a new coil.

Another common leak area is the shaft seal on the compressor. The hoses do leak ever so slightly but I have seen cars go their entire life without ever having to be re-filled. Due to this assumed slight seeping of the hoses, the industry has gotten away with "topping up" of the refrigerant without diligent searching and repairing of leaks. This is not the case on other refrigeration systems. This approach adds to the nickle & diming of the customer instead of correctly repairing the system in the first place.