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AC compressor stopped working

Hello, all. I’ve got an issue with my AC.

Current issue: AC does not blow cold. I can hear/feel that the compressor is not turning on. Background below.

Background: Approximately a year ago, my AC was working only intermittently. On days when it was less than 90°F or so, it worked fine. On days when it was higher than that, the compressor would switch on and switch off every few seconds for maybe ten minutes, then it would usually stay on and work for the rest of my drive. It could have been just a coincidence that the compressor would work or not work based on the outdoor temperature, but it certainly seemed to be that way over a month or so of observation.

A mechanic friend theorized that either I was low on freon or my low pressure switch was bad. The freon was the cheaper option, so he charged it. He did not, however, trust his pressure gauge to accurately determine the pressure, so he was not sure if it needed freon or if he put the right amount of pressure in. The problem persisted, though the hot season passed and it was no longer something on my mind.

This summer, it gets hot again and my AC is working fine. The compressor was not doing the thing where it turns on and off, it just stayed on. Then, a week ago, after no change that I am aware of, the compressor will not turn on at all regardless of the outdoor temperature.

My completely unqualified theories:

  • Bad low pressure switch. I don’t know what that would look like, but someone more knowledgeable than me said it.
  • Freon leak. But why would it have worked just fine for a few months up until a week ago?
  • Freon pressure too high. But again, why was it working before the last week?
  • Air in AC system. Other than getting freon added by a friend, I have never had any proper AC maintenance, so maybe?
  • Electrical issue with compressor. This sounds the most expensive, so I am actively trying not to believe it.

So, has anyone got any wild theories? Maybe a course of action I should follow? Any ideas would be appreciated.

Doesn’t matter what theories anyone comes up with if they can’t examine the car. See a mechanic.

That’s entirely reasonable. I’m just not sure what type of service to get or how much I should expect to pay. Some auto shops near me are offering to flush and charge the system for about $150. But I don’t even know if that is my problem.

The first thing that’s done before anything else is, connect a manifold gauge set to the AC system to determine the state of charge of the refrigerant.


You don’t tell the shop what the fix is and you don’t buy an advertised special and hope that fixes it. You go to a real mechanic, if he is any good you may have to make an appointment.

You tell him what the problem is, any work that has been done to try and fix it and let him diagnose the problem and give you an estimate.


Why would you try that before you have the problem diagnosed ?
You need to go to a shop that specializes in AC

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