# HVAC condenser cooling fan capacitor starter



## mpcxl (Dec 9, 2015)

Any hvac gurus out there ? 

So, cooling fan does not run on unit. However fan/motor spins freely by hand 

I’m guessing it’s the starter capacitor. It’s also tied in with another black capacitor. 

Should I swap both of these out or is there another underlying issue ?


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## mpcxl (Dec 9, 2015)

Picture


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## JoeSparky (Mar 25, 2010)

The capacitor is dirt cheap. Not a bad place to start. If it is mis-shapen in any way, it's definitely bad. The motors don't necessarily have to be seized to be bad. Could be a burned winding.
All that being said, that black capacitor is a hard start cap. They are most of the time used as a band aid to prolong the life of older compressors. Looks like there is another burned up part that was disconnected and abandoned in place in that pic. Probably not doing your customer any favors by repairing that turd :vs_poop:


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## MTW (Aug 28, 2013)

I agree with Joe especially if it's R-22, that whole unit needs to hit the road.


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## Cow (Jan 16, 2008)

If you think it's the capacitors, why aren't you testing them to be sure?


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## HertzHound (Jan 22, 2019)

The black hard start capacitor only goes in parallel with the compressor capacitor . It doesn’t have anything to do with the fan and probably doesn’t need to be replaced. The silver capacitor is the one to change if anything. It is a dual capacitor. It has a common terminal, a terminal for the fan and a terminal for the compressor. They are all run capacitors. They don’t get switched out of the circuit. Check the capacitor with your multimeter. And like joe said, if there domed, there probably bad. 

Mine has a hard start capacitor since the day it was installed. I’m not sure why. Although there was a small orafice in a bag left behind. That probably needed to be swapped with the one that’s in there somewhere. I don’t think I have a voltage drop problem to need the hard start capacitor. 

Your unit looks old and was probably built well to last this long. The one you replace it with is probably designed to last five years. Good luck.


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## gpop (May 14, 2018)

If its your personal unit

silver cap is a dual something like a 45/5. The black one is for the compressor so its nothing to do with the fan.

Find the winding's to the fan then ohm them (wire color will be on the back of the panel you removed). If it ohms open it could be the thermal switch in the motor. Check to see if its physically hot. 
If it ohms open and the motor is cold then check the wiring it not uncommon for the blades to eat the wires. If its not that then the fan is probably toast.

Motor cold and ohms good then you can turn it on and bump start it with a screw driver (just to confirm its the cap and not the cap and motor). If its just a bad cap it will run once you give it direction. If it can't flick the fan and make it turn then the bushing in the motor is bad (seized).


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## pjones (Oct 7, 2019)

JoeSparky said:


> The capacitor is dirt cheap. Not a bad place to start. If it is mis-shapen in any way, it's definitely bad. The motors don't necessarily have to be seized to be bad. Could be a burned winding.
> All that being said, that black capacitor is a hard start cap. They are most of the time used as a band aid to prolong the life of older compressors. Looks like there is another burned up part that was disconnected and abandoned in place in that pic. Probably not doing your customer any favors by repairing that turd :vs_poop:




That burned up part is a positive temperature coefficient resistor. That one clearly burned up and it was replaced using a hard start kit. Sloppy workmanship left it in the condenser instead of removing it. That issue has been resolved so can’t condemn the condenser because of that. In this case it would have been installed to replace a factory part so probably not used as a bandaid in this instance. Have a look at the wiring diagram. It will tell you what was originally installed. Sometimes the install manual will spec them due to certain design conditions. Can’t fault it for having a hard start kit without knowing more details, but from what I see it’s there to replace the PTC that was there prior. Nothing wrong with that. 

As others said the black one is your hard start kit and serves the compressor. It should be connected to the C and HERM connections on the dual cap. Test the run capacitor to see if it’s within spec. If it’s out of its tolerance then replace it. It’s harder to test the hard start kit because it will have a switch to remove it from the circuit all that is inside the capacitor. It also has a bleed resistor. They can be checked but it’s a lot of work and requires dismantling the capacitor assembly. 

Ohm out your motor windings while you are at it. If the motor is warm but there is no other sign of life then that’s a good sign. Wait for it to cool down and check again. If it’s warm and humming then probably has worn bushings. If it’s just the cap that’s failed then you can typically start the fan motor like an old airplane prop. Once it starts spinning then it will run (poorly but it will run until it over heats and fails), replace the cap and return it to service. 

If the motor windings are discoloured due to heat then you will probably find it’s going to fail very soon or preform badly. Sometimes they can last years but it’s a bit of a gamble at that point since the bushings oil wicks have often caramelized due to the heat and your bushings will either gum up or wear out soon after). If it’s your own you can take it out and fix it, but if it’s a customers then it’s cheeper to run to a supplier and replace the motor. I also find motors with overheated windings tend to produce less power and that may cause high head pressure issues. You may have better luck if the shaft uses bearings rather than bushings, but those would have seen the heat stress too so be mindful of it either way. 

Clean out the unit while you are at it. They can last a long time if you take care of them properly 




Sent from my iPhone using Tapatalk


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## macmikeman (Jan 23, 2007)

I replaced one of my smaller split system Mitsubishi ac's on Wed. Inside of it was the fan , the coils, the compressor, and a capacitor. All the controls for this were located inside on the fan coil unit. Inside the new replacement outdoor unit is the circuit board assembly controlling the compressor and the inside fan coil unit. The ac tech I hired for the job suggested buying CRC plastic coat spray for the circuit board to prevent short circuit from small lizards attracted to the warmth of the board when running. 


All ass backwards if you wan't my opinion.


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## NoBot (Oct 12, 2019)

Test it.
Dead short the capacitor with a screw driver across the terminals.
Remove all wires
Set you meter to continuity
Touch the two test leads onto the capacity
Set the meter for DC voltage
Test for voltage
The voltage should pike and go to zero.
If no voltage, capacitor is bad.

Use DC voltage test because you charged it with a DC battery inside your meter.


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## macmikeman (Jan 23, 2007)

This ^^^^^^^^^^^^^^^^^^^^^


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