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I have an ICP gas furnace which won't start and I've diagnosed the problem to a bad capacitor on the inducer motor. The motor spins freely and measures good resistance, so I'm going to try replacing just the capacitor. How can I determine the correct size capacitor for this motor? The existing one is 1uF, but I don't know if this is the correct part. I'm wondering if maybe the reason it failed is that it's undersized. I have no HVAC expertise, but from reading online it sounds like 5 or 10uF is more common.

The motor is Fasco model HC30CK238 and the furnace model is PGX436060K01A1.

motor capacitor

3 Answers 3

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The first photo shows "1 MFD/440 VAC" on the label just next to the capacitor sign, which is the specified value for the capacitor:

1 Micro FaraD, 440 Volt AC.

Very unlikely, but still possible: Since the label could be wrong, e.g. belonging to another type of motor, a mail to the manufacturer including a photo of identifying markings on the motor (if applicable) would be helpful.

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  • Thanks! I didn’t know that’s what MFD meant.
    – Elliott B
    Dec 18, 2021 at 2:07
  • The “1.0uF” on the capacitor means the same thing - 1 micro farad.
    – nobody
    Dec 18, 2021 at 2:38
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    The motor voltage is 208-230 telling me that this is probably an electric heating unit and not a gas or oil unit
    – d.george
    Dec 18, 2021 at 11:18
  • @d.george why, do you think it’s unusual? The heat is gas and the AC is electric. I was surprised by the 230 max voltage though, since most things tolerate up to 240. My house is usually about 234V.
    – Elliott B
    Dec 19, 2021 at 5:50
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That motor is plainly labeled 208-230V. Most gas furnaces are 120V.

I would measure the power being delivered to the motor by the furnace, and make sure it is 208-240v.

Because of the way AC induction motors work, the wrong voltage won't make the motor go half the speed, it will make it run hot and rather badly. Could burn it up.

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  • The power going into the motor is 230V. This does not answer the question.
    – Elliott B
    Dec 18, 2021 at 10:50
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As was previously mentioned,the “1.0 uF” on the capacitor means the same thing as 1 MFD. The "1 MFD" is listed right on the name plate of the motor so I'd have to assume it's what the motor was designed to use. The motor's only pulling .35 Amps and most on the ones I've installed pulled .5 Amps. The voltage listed on a capacitor can be a lot more than the supply since it's a limiting factor but the uF has to be close to the design number. You can usually increase the uF 10 -20% but no more than that. I wouldn't be increasing it to 5 or 10 uF just based on the nameplate.

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