Chrysler 300M Enthusiasts Club
  • What causes the AC compressor to lock up?

  • Repair Questions and Answers.
Carlisle Chrysler Nationals

Membership Banner

Repair Questions and Answers.

Moderator: Moderators

 #379936  by piperdog
 July 22nd, 2019, 7:38 pm
What causes the AC compressor or its clutch to freeze up?

Seven weeks ago on the highway my AC belt started screaming. By the time I pulled off to the side of the road the belt was shredding and melting. I cut if off, continued on my way, and then replaced the belt. At the time, I thought the issue was because I had an old, worn belt and that it may not have been tight enough. I drove with no issues until this morning when parking in the lot at the train station. The belt started screaming again. This time I was able to stop before the belt disintegrated, although it was smoking! I realized then that the cause was likely the AC compressor locking up. I turned the AC off and was able to park the car. When I returned this evening to drive home, I was able to validate the issue. As soon as I turned the AC on it screamed and as soon as the AC turned off it was quiet. I drove home and parked. However, I tried it again a few moments ago and there was no issue with the AC on. The only other thing that I can add is that my refrigerant is likely a bit low. This spring I was getting no cooling so I added some refrigerant a couple of weeks ago and it has had sufficient cooling since although I don't think it is as cold as it should be (I should measure the temperature delta - I know!).

Any thoughts would be appreciated re the issue and the AC compressor.

User avatar
 #379938  by FIREM
 July 23rd, 2019, 5:56 am
There is oil in the A/C system (vapor) that is carried thru the system with the refrigerant. Low charge can cause low oil circulation. Also refrigerant leaks will carry traces of the oil out as it leaks. Low oil, lack of lube, compressor seizes.
The system holds 5 ounces and it tends to collect in various areas of the system. When components are replaced oil needs to be added.
You will likely need to replace the compressor and if debris are in the outlet line, the line and the condenser should also be replaced.
User avatar
 #379985  by hrmwrm
 July 25th, 2019, 4:25 pm
too loose belt or overcharged and running too high pressures if the ac works at times too.
 #380365  by piperdog
 August 18th, 2019, 11:34 am
Update on my AC

Finally had time to take the M into the garage where they evacuated, recovered and then refilled the AC. I had not run the AC for several weeks since the last time I had a seize-up of the compressor - although I did turn it on a couple of times for a few seconds and it was fine so it wasn't permanently seized. The tech recovered only 0.2 lbs of R134A so the system was really low. He refilled it to close to spec at 1.5 lbs. It took him two tries because the first time it would only take 1/2 the charge so he recovered and charged again. He thought that may be due to some debris blocking the line somewhere. I think he may also have added 2 oz of oil but I'm not exactly sure about that.

The AC is running ice cold for the moment (after two days). I'm going to run it until I encounter another compressor seize-up. If that happens, I'll replace the compressor and condenser.