Carrier heat pump humms but doesn't turn/spin on


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Old 08-04-18, 08:29 AM
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Carrier heat pump humms but doesn't turn/spin on

I've got a 12 year old Carrier Heat Pump that has been working fairly reliably. I had to have the refrigerant refilled a couple of times over the last 6 years, but otherwise, I haven't had any significant issues. I use it 12 months a year - in summer for cooling and winter for heating.

Yesterday, however, it suddenly quit working on me; it does not turn on any more. When I call for cool from the tstat, I hear a click and a humm from the heat pump, but that's about it. It stops, waits a couple of mins and humms and stops again. The fan does not spin, nor do I hear the compressor running.

I tried resetting breakers/etc, but it hasn't made any difference.

I pulled off the cover on the outdoor unit, and validated that I am getting 220 to the HP, and that the tstat wiring is correct. Additionally, I can see the power relay closing when the white tstat line is powered.

I poked a stick into the top to see if the fan was seized and it spins freely.

Although an avid DIY guy, I'm not very learned on Heat Pumps circuitry, nor how the system works or what could be causing these symptoms. Other posts have tended to indicate the capacitor could be a culprit, but I don't see any particular bulging/etc on it. But then again, I don't have a new one to compare with. Is there a finite lifespan to these caps? I'm attaching a pic - perhaps someone can give me a second opinion? (the pic was taken portrait mode, but cannot figure out how to rotate it on this site)

What can cause these symptoms? Is there a way to test if the cap is defective and/or bypass it to test out the theory? I would expect the capacitor to be used for the startup of the compressor; why would it affect the fan? Is there circuitry in the compressor which controls the fan spin up?

I don't know if it directly relevant or not, but I did check the furnace filters and noticed they were quite dirty and changed them. Could clogged filters have contributed/caused this situation?

Thanks for any insight.

Eric
 
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Old 08-04-18, 10:35 AM
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Your dual capacitor looks swollen to me. You will need to replace it.

Help with condensing unit and fan motor size
 
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Old 08-04-18, 12:44 PM
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Thanks. I'm struggling to find a place open on the weekend that carries them in Montreal. Looks like it is going to be a hot weekend.
​​​​​
Can I replace the dual 60/7.5uF cap with two individual caps instead if I can't find a dual one? Both would need to be 440VAC right? Or does the fan cap require less voltage?

Thanks,

Eric
 
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Old 08-04-18, 03:33 PM
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Yes you can replace your dual capacitor with separate capacitors.
You will need to bridge the common terminal to one side of the new separate fan capacitor. ( Place a jumper wire from com on the dual cap to one side of the new fan cap)


The fan can accept a 370VAC run cap.
 
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Old 08-04-18, 07:00 PM
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Thanks. That's pretty much what I expected. After searching the better part of the day, I found a single place that might stock a made in China cap that is open on Sunday. It's actually a dual 60/5.5 and a separate 7.5uF run capacitor. Hopefully I'll be able to tie wrap them both in place.

I'm going to call in the morning and make a trip out there if they have what I need to see if I can get this unit running again. With windows wide open, the house is still at 28C.

Thanks,
Eric
 
 

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