My outside fan (compressor?) will not turn on. I have a week or two before the weather gets warm so thought I would try fixing it before I hire someone.

Symptoms - I turn on the air. The blower turns on. Nothing outside makes a sound or moves. Now the last time I used the air conditioner in the fall it cranked up VERY loud outside. Where I went over to see what the hell was going on. Well it lasted for a couple minutes and then worked fine. Tried to turn it on a few days ago for the first time this year and nothing outside came on.

What I have done so far. All I have done so far is check that electricity is going to the outside unit. I tested it with a voltage meter and things are flowing correctly.

I am an air conditioner noob so please help. I can do whatever or take pictures if needed. The outside unit is only 3 years old.

  • 1
    Contact the company who installed the unit, after only 3 years it's extremely likely the unit is still under warranty. HVAC is not a n00b friendly area of home repair.
    – Tester101
    Commented Apr 9, 2013 at 18:38
  • Company that did it folded. I just want to make sure it isn't something simple before I pay a couple hundred.
    – DMoore
    Commented Apr 10, 2013 at 5:33
  • Was it the local installer that folded? Because the warranty probably comes from the equipment manufacturer. I would try to find the closest active dealer for the brand - they should be able to do warranty work. Commented Apr 13, 2013 at 21:31
  • How mechanically savvy are you? Is it outside your tinkering to take the unit apart and see what's going on? The installation company went under, but maybe you can get the repair manual from the manufacturer and order replacement parts directly from them. Once you get the unit open it may be obvious what needs replacing is what I'm getting at.
    – MDMoore313
    Commented Apr 15, 2013 at 15:42
  • I am going to see if I can contact the manufacturer. I am savvy enough to see there are only a few components to it. I just don't know where to start. Am I definitely dealing with an issue with the outside unit? Is there something inside that would keep the outside unit from coming on?
    – DMoore
    Commented Apr 15, 2013 at 16:30

4 Answers 4


Besides checking the fuses/breakers, the fan, and any connections on the controller, there's not a lot of user serviceable parts on an HVAC system. This is because the refrigerant lines require specialized equipment to test for refrigerant levels, a license to buy more refrigerant, and even more equipment to remove the refrigerant so you can work on the compressor.

When the outside unit doesn't turn on, checking the refrigerant is typically the first step because there's a safety switch in the system that prevents the compressor from turning on without enough pressure in the lines. Without that, the compressor would turn on and burn itself out since the refrigerant also includes the lubricant for the compressor.

Do what you can to get the warranty coverage from the manufacturer, but realize that this is a situation that will almost certainly require a professional to come out and repair for you.


I had a similar issue a few times with my AC unit. The issue both times was a bad capacitor in the outdoor unit. The repair guy was in and out in about 15 minutes (including diagnosis).

  • You will find that a/c supply stores will not want to sell you anything if you aren't a contractor, but you can pick one up at grainger.
    – Edwin
    Commented Apr 18, 2013 at 12:54

This has happened to mine regularly before I replaced the entire HVAC system. There is a relay switch that turns the outside fan on and its located in the outside unit beneath the panel. It is extremely common for ants and other bugs to crawl into these relays and get fried leaving the relay melted or cracked like a miniature bomb went off. Sometimes you can take the relay out and repair it with some crazy clue if the body is just cracked. There is a spring and will need to be checked and possibly bent back into shape or replaced. Your best bet is to get a new double pole relay so that there is are two paths to turn the outside fan on. That way if another bug crawls in there and Kamikaze's one of the poles the other one will still be in working condition. I remember having to order mine from a local HVAC supply but you might be able to find them on amazon or some website too.
Also, lay down an extreme amount of bug killer around the unit to keep the bugs out. Its usually ants that cause this.

Double pole relay switch


There was rusted/corroded wiring in the actual unit. This is at both capacitor and the relay(?). I was getting voltage - 240 - to the relay but not out correctly out of it. Asking more specific question for the rust issue.

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