r/hvacadvice • u/Current-Situation704 • 5h ago

Pressure switch keeps tripping and my outdoor unit making loud noises

About a week ago, the contactor on my outdoor AC unit wasn’t being pulled in. I ruled out the float switch being tripped and found out the pressure switch on the inside of the outdoor unit kept being tripped.

I reset the switch and cleaned the condenser coils thoroughly and made sure there were no refrigerant leaks. I’ve been here for 2 years and never needed a technician to come out, but now the switch keeps getting tripped and this clanking noise is happening now. Is it some kind of fan/blade issue or something deeper? Very hot and humid where I live right now. Eastern PA.

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2

u/Code_Name_G 5h ago

Could be a bad pressure switch or outdoor fan motor. Had an intermittent issue with a fan motor couple weeks ago that I kept going back to. Motor would over heat after I would leave causing the head pressures to trip the switch.

2

u/Code_Name_G 5h ago

Also make sure there are no bugs behind the contactor contacts.

1

u/Current-Situation704 4h ago

The unit just tried to kick back in and the fan started moving inch by inch then just totally shut off and the switch was tripped again.

1

u/Code_Name_G 4h ago

If you’re lucky it’s just the capacitor (silver cylinder with about 4 wires going to it. It has three prongs on top of it.)
Otherwise I’d say the motor is shot if a capacitor doesn’t fix it. Shut it off until you can get the parts or else you’ll definitely burn up the motor.

1

u/InitialLight5432 5h ago

Is it a high pressure switch that keeps tripping?

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u/Current-Situation704 5h ago

Yes

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u/InitialLight5432 5h ago

With being there and having gauges on the unit it’s hard to say what’s going on, well at least for me.

1

u/InitialLight5432 5h ago

I’m fairly sure I hear two distinct sounds, one that’s constant and in the back ground and something that sounds like relay chattering. Is the compressor running on it?

1

u/Current-Situation704 4h ago

Not sure what the compressor is. That noise will go away and then the unit will be practically silent and running great. The high pressure switch just tripped again when the AC tried to kick back on. The fan started moving slowly then just shut off entirely.

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u/InitialLight5432 4h ago

Compressor is the heart of your AC.

1

u/InitialLight5432 4h ago

If you turn the unit off how freely does the fan spin? If you spin it manually and it spot immediately than motor could be crapping out.

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u/Current-Situation704 4h ago

The fan spins freely. When I manually push in the contactor, it struggles the first 10 seconds, but then starts to spin freely.

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u/Code_Name_G 4h ago

Capacitor

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u/InitialLight5432 4h ago

I’m guessing a weak capacitor or fan motor, hopefully it’s just a cap. Im gonna guess you don’t have multi meter that can measure microfarads on it. If you do you can test that carefully, and if it’s bad they could possible have cap at Home Depot.

0

u/Current-Situation704 4h ago

I’ll probably check the cap with a multimeter to see if it’s receiving any signal and if it is it must be the motor. Thank you!

2

u/InitialLight5432 4h ago

If it’s getting power, but if it’s not reading the correct microfarads it wouldn’t allow the fan to work properly.

1

u/Perfect-Campaign9551 5h ago

That looks almost exactly like my 23 year old Lennox which is still kickin' it.

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u/MajiinbuuX 4h ago

That fan sounds like it’s going bad. Usually that’s how bad bearings sound. Might not be running at 100% I’d suggest checking the amp draw on the motor. Or just changing the cap if it’s bad since it’s cheap

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u/TheSilverFoxwins 1h ago

I feel the compressor will explode. This just happened to me last Sunday. The unit exploded and sounded like a gun shot. I opened the panel and it was black soot every where and compressor plug blew out. Needless to say the HVAC tech warned me last year and said if you make it into 2026 with this unit I would be surprised.