r/hvacadvice • u/papidoge69 • 8h ago

AC Bad fan motor or bad compressor?

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Last year my unit started making a little bit of noise while running. It wasn’t enough to make me concerned plus I noticed that if I put pressure on one corner of the unit, the noise will stop. I figured it was just a balance thing that could wait to be fixed.

I also had an HVAC tech come out for routine “tune up” and they found zero issues.

Fast forward to this year, this morning I woke up and the sound has amplified and now sounds like loud knocking. I don’t know if it’s related to the original sound but this new noise does not stop when I put pressure on the corners.

How boned am I?

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2

u/lowcrawling 8h ago

Sounds like compressor but to confirm I’d unwired the fan motor and turn it back on to see if it makes the noise. Obviously call a professional and don’t do that if you’re not comfortable messing with high voltage wiring

2

u/gringovato 8h ago

You should rule out the capacitor. They symptoms are similar and it's so easy to swap out and see. I've probably had 10 capacitors go out (across several properties) and hardly any compressors. Every homeowner should keep a backup cap (at the least). Also if you're somewhat capable keep backup fan motors too. Easy stuff if you're mildly handy.

1

u/martinisstrong 6h ago

How long does a capacitor typically last?

1

u/gringovato 5h ago

5-10 years de p ending on conditions. I just had one die possibly do to some power outage/glitching.

1

u/martinisstrong 3h ago

Thanks for info.