AC compressor was locked but now unlocked? Now what?

Yesterday I noticed that my AC was not blowing cold in my 2006 Dodge Caravan. I bought one of those AC recharge cans from Walmart, hooked it up and started dispensing it while the car was running and the AC was blowing. Pretty quickly I heard a belt squeak and the car turned off. If I tried to turn the car on again while the AC or defrost was on it would turn off within a second. I could start and run the car fine with the AC or defrost off.
So I figured that I somehow locked up my AC compressor by adding too much pressure to the system. However, when I went out this morning and started the car up, I could run the AC and defrost with no problem. There was still no cold air though. Does this mean that the compressor is no longer locked up?
Any advice or thoughts on how to proceed?

When you added refrigerant the pressure was able to engage the pump. When pump engaged it locked up. Letting it set overnight allowed the refrigerant to escape through a leak in the system. Now the pump will not engage. You probably have a broken pump (compressor).


Thank-you, that makes sense. So I might have at least two problems: a bad pump and a leak. Should I take it into a mechanic to have it looked at? I’m in Georgia so I’ll need AC in the car this summer.

Yes A/C systems are not really DIY friendly


Yes, take it to a licensed AC shop. I was also thinking you may have introduced the refrigerant into the compressor in liquid form and hydro locked it.

What is most likely is that you ran the high side pressure too high stalling the compressor. My boss at a air conditioning shop once told me to always connect the gauges up first, even if the problem might be elsewhere because you now became the expert. Then you could search for the system leak.

Yes, this requires a shop with AC expertise, or an AC specialist. A little forewarning: the fix could prove to be quite expensive. Start saving up, you may need some extra cash. fyi, Here’s a pretty good 4-part tutorial on automotive AC.

I figured I should come back here and update this:
The first shop I took it to said that the compressor was torn up and that the entire system needed to be replaced for $1300. That’s too much to spend on this car, so I took it to a second place. The second guy said that the compressor was fine. He charged $65 to add refrigerant and it now blows cold air. He said that there is probably a leak somewhere but that it might be better to just see if it gets through the summer. The compressor now seems to whine a bit when the RPMs on the van are high, but it’s possible that that’s just a new sound that wasn’t there when the refrigerant was too low for the pump to engage.

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Good to hear you have the AC working again. Perhaps there are remaining goblins lurking somewhere among the tubes and fins, but cross your fingers, and you may be good to go, at least for this summer. If you have a leak and it stops working, it might make $$$ sense to just take it back to the same shop and have them re-fill it again. It’s important these gadgets don’t get overfilled, so best to have a shop that can determine the exact amount needed to fill, rather than trying to do it yourself without the necessary test and diagnostic instruments an AC specialist shop will have. For example the proper way to add refridgerant is to pump out all the refridgerant into a holding tank, then fill the system w the exact weight of refrigerant needed to fill the system. That job is difficult to do unless you have a vacuum pump, holding tank, gauges, etc.