What do I need to know before I replace capacitor in HVAC heat pump outside unit?

[Dennis S]

This is the one I have picked out.

https://www.amazon.com/40-MFD-370-440-Co...5?dchild=1&keywords=40+5+capacitor&qid=1619462632&sprefix=40+5+&sr=8-5

I did it a long time ago. The 40/5 matches the existing number and both are soup can shaped. I'll switch the breakers to the unit and for the whole house. If I remember right, the only tricky part is matching the wires to the new one. An iPhone camera should help with that as well as a note pad.

The outside unit has gotten haphazard about starting.

[Dennis S]

Bonus question: If the thermostat turns on the inside unit but the outside one doesn't kick on, will it hurt anything?

[space-time]

you need to know that capacitors can store enough energy to be dangerous.

So you need to trip the circuit breakers and check capacitors for voltage and discharge if necessary.

[deckeda]

https://www.youtube.com/watch?v=HES4LVQDvJc

Or you could do like he said he sometimes does it and just short the terminals. NOTE: Discharging a capacitor by shorting it could turn it into a projectile. Learned that in high school shop class.

If the thermostat turns on the inside unit but the outside one doesn't kick on, will it hurt anything?

I'd expect the system inside to know if the outside didn't turn on and report a problem.

[Ombligo]

Trip the breaker to both the inside and outside units - then the thermostat can do whatever it likes and no one cares

[Cary]

Yep - discharge the capacitors, preferably not by using your body to bridge the terminals.

Use a screwdriver with a plastic handle or a wire with good insulation to short the terminals.

[Bernie]

Any voltage from the thermostat is LOW VOLTAGE. Just turn the cooling to off or set the temperature to 99. Disconnect power to outside unit.

If you cap had any Kick you would not be replacing it.

Use a long flat blade screwdriver to pry the connector while shorting it to the case.

[Dennis S]

It came on the first time today. Even if it continues to start every time, I'll get a capacitor since they are so cheap. The last time it went out I had to drive 60 miles to get one quick enough. Also, I'll check the outside unit for ants, since that caused a $100-200 service call one time it wouldn't kick on.

[Bernie]

A 9 volt battery for a smoke alarm is $5.00 yearly.

The filters for your Central Air are how much a year?

ROI on a capacitor.......Priceless!

[macphanatic]

If you trip both breakers, the thermostat should go off. They are typically powered by a transformer in the furnace. You could just flip the switch that is supposed to be located at the furnace instead of tripping it's breaker. Then just pull the disconnect outside.

Use a screwdriver or pliers with insulated handles to short the terminals.