Capacitor quandry

bshultz

Okay, so I am relatively new to hvac, and especially capacitors. Serviced a 3 ton High Efficiency Unit - variable speed fan on condenser. Fan was pulling 9 amps - rating says .8 so we (my boss and I) change it out 50uf+5uf but only have a 45uf+5uf in the van. Checked the amp reading again, fan is now pulling .8 amps and compressor 9 amps.

systems works great for 6 hours.

Went back at 7 pm, compressor runs, but fan won't. The capacitor is hot as a firecracker. We pulled it and changed it out with a 50uf+5uf (we picked one up later to keep in the van). Checked original new capacitor and it is fine. Flipped on unit and everything is back to normal. We monitored it for about 20 min. and everything is good to go.

2 Hours later - call, A/C quit working.

Planning on looking at the fan motor in the morning, possible replacement.

We are both a little stumped - any insight?

hvaclover

VS cond fan mtr?

You better double check the schmatic. What brand and model was it?

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Not Stupid, Just slow

bshultz

I apologize, the fan motor was a two speed motor - spent too much time in the heat yesterday.

Brian

JJDH

How hot is the motor? Could be thermally protected.

ccc256

if the motor got real hot the lube in the felt pads is more than likley gone after the motor cools down then restarted the bearings are likley heating up and siezing just a thought

hvaclover

I don't think that is accurate.
A motor seize will occur with a mechanical failure, like a bearing failure.

But the normal OL protected on a typical cond fan motor will trip before the motor over heats to winding or lube break down.

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Not Stupid, Just slow

ccc256

we would be out of jobs if over loads and safetys worked 100%all of the time.i can't tell you how many times i have been told "thats not possible"when in fact "anything is possible"

hvaclover

I did not say it's "not possible". I said I didn't think the statement made was "Not accurate". Which is a long way from not possible.

I have been around this business so long (fourty to be exact) I have become so jaded that nothing surprises me any longer, so I don't use the term "that isn't possible".

Remind me to tell you about the plugged chimney that turned out to have five bags of body parts in it. That made national news about twenty five years ago.

__________________
Not Stupid, Just slow