Capacitor Help Please!

AaronK4040 · August 7

I came home a couple days ago,

and it was 81 degrees in the house. Outside unit was running as was inside unit, but the blower was not. After some research I believe the start capacitator is bad. I have changed capacitors before and they have always been mounted to the fan housing. Both capacitors for this unit were found inside the motor wiring cover. (Pictured below) It does not appear these are soldered to anything, and there are no wires going to them. Do they make capacitors with the stabs you push in and twist to lock in place? This is a 1/2 HP Broad Ocean motor if that helps. Thanks in advance.

HVACNUT · August 7

How did you test the capacitor(s) ? Allowance is +/- 5%.

Was the system frozen?

AaronK4040 · August 7

Yes the system was frozen. I wasn't really sure how to test them since I cannot access the terminals or see wiring. Inside unit is still getting cold, just the fan will not kick on. Fan spins freely by hand.

mattmia2 · August 7

those caps are potted, there is a printed circuit board embedded in that gray potting compound and are caps for a switching power supply, not an induction motor. that probably uses a vfd or variable voltage to run the fan motor. Those caps could be that supply or they could just be rfi suppression or power factor correction.

Ironman · August 7

That motor is not field serviceable. If it’s bad, it must be replaced along with its control board.

ratio · August 7

That looks like the bell end of an ECM motor. Like @Ironman said, not field serviceable. I have heard that replacement bell ends are available if the field windings aren't damaged, that might be something to look in to. A universal replacement is a possibility as well, some can be field programmed pretty specifically (via WiFi) for your application.

pecmsg · August 7

how old is this motor?

EdTheHeaterMan · August 7

https://forum.heatinghelp.com/discussion/comment/1861816#Comment_1861816

probably as old as the furnace!🤪

pecmsg · August 7

https://forum.heatinghelp.com/discussion/comment/1861836#Comment_1861836

ASSUM - ing?

HVACNUT · August 7

So no actual diagnostics. You could try replacing the module alone, but who knows if the motor is good?

Assuming its a 230 volt air handler, is the motor getting 230 volts? Is the motor getting 24 volts?

This is an ECM constant torque motor. There is no external run capacitor.

109A_5 · August 8

Yeah, probably not the DC Bus capacitors. Not a high failure item. However if you really want to try your luck changing them (probably soldered to a circuit board as previously mentioned) Digikey.com or Mouser.com. More likely there is a much smaller aluminum electrolytic capacitor that the ESR (Equivalent Series Resistance) is now too high and the switching controller won't start .

This looks disconnected, if so was it on purpose ?

109A_5 · August 8

All fuses good ?

BTW if you do change any aluminum electrolytic capacitors they are typically polarity sensitive.

Just to be clear a start Capacitor or Bootstrap Capacitor in a switching power supply (or motor drive) is usually a small aluminum electrolytic capacitor unlike the larger in physical size DC Bus capacitors or AC capacitors for capacitor start induction motors.

Anyway the capacitors you photographed probably looks something like this on the business end.