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A few times over the past two weeks, my central AC unit would stop producing cool air. The inside fan (furnace blower?) would be working, but since the fan on the outside condenser was not running it would just blow warm air around.

One time when this happened, I hosed down the outside unit and it just started up on its own after a minute or two.

The next time, hosing it down did not work. I viewed some youtube videos on basic tests.

  • I checked the capacitor and the numbers were in tolerance and there was no visible buldges, etc.
  • I checked the voltage on the relay/bridge and also tried physically activating it when there were issues
  • Checked for lose wires, bugs stuck under parts, etc.
  • When the unit started working again, I felt the line and it was ice cold/sweating when working normally
  • I didn't see anything iced up on the inside unit when I checked, but maybe I didn't look in the correct place?

There does look to be some build up / gunk on the fan motor area and it sounds a little bit off, but it still runs most of the time.

In a few cases, I would switch the AC unit off at the breaker, pull the fuse on the outside wall connection, reset both, then turn the thermostat on/off. After few minutes with resetting everything the outside fan spins, cold air is blowing inside.

This generally seems to work and typically the problems start at night after the sun sets.

I am trying to figure out what I can/should test next on my own before I call an HVAC company. My thought was maybe there is an issue with the fan, that the thermostat is not actually calling the outside unit, or there is some other electrical issue.

The unit is a carrier CA13NA060-C. The unit is less than 5 years old.

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    There are two motors in the outside unit: the one you see turns the fan wihle the other is inside the compressor pumping refrigerant. Does either one run while the other has stopped? Since you're clearly handy with a meter, check whether there is appropriate voltage on the contactor output during one of these times when there's a call for cooling but things aren't running.
    – Greg Hill
    Commented Sep 15, 2023 at 19:35
  • Hosing it to work means the compressor is in high temp lockout, assuming the condenser's fan is in order. If it isn't then you may be "experiencing high head pressure". But sounds like it was installed w/o pulling 500 micron bar and moisture broke it. 5y and then it dies? Yeah, they sucked. Or rather didn't.
    – Mazura
    Commented Sep 28, 2023 at 1:31
  • @Mazura can you explain more: "sounds like it was installed w/o pulling 500 micron bar" - what should I look for in this case; it is possible its "broken" even if then later works?
    – HelpEric
    Commented Oct 2, 2023 at 19:29
  • Last one I did I took a picture of the gauge reading 430 for bragging rights. W/o one of those the only thing 'to look for' is a dead 5yo compressor, which means it was either a lemon, or someone cheated while installing it and didn't pull a hard enough vacuum to ensure all the moisture was out, which is like really freaking important for anything after R-22.
    – Mazura
    Commented Oct 2, 2023 at 23:23

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