Supco Hard start capacitor on Coleman A/C
I have a 1996 camper with a Coleman A/C. I bought the Supco SPP6E. My A/C has 2 round capacitors, one small and one large. The small one has 2 wires and the large has 3 wires. Which one do I replace?...
Forum Discussion
Golden_HVAC wrote:
As a general rule, yes you must have at least the minimum voltage rating of the replacement capacitor as the expected running voltage in the system. So a 120 volt compressor will see upwards of 175 volts at it's run capacitor, thus the minimum rating of 370 volts.
That said, a start capacitor with relay to take that compressor out of the circuit once the compressor is running must be properly sized. Oversize it and the correct "Drop out" voltage will not be obtained in time or at all. So a start relay that works great on a 220 volt compressor and drops out the capacitor at 190 volts on the start to run winding will work great with 200 - 250 volts input to the compressor. However move it to a 120 volt compressor, and it will never drop out, unless it has a back up timer circuit to take the start capacitor out of the circuit after a certain time has gone by. The SPP6E does have a electronic timer, and anyone putting this 220 volt capacitor on a 120 volt circuit is doing so hoping that the timer keeps working. The capacitor has a maximum working volt rating around 300 - 370 volts, so that is not a problem, the problem is the minimum voltage to drop out the start capacitor is well above what a 120 volt compressor will run at.
The SPP4E is the correct start capacitor for a 120 volt compressor, and will drop out at the correct voltage, even if the time circuit fails.
You present your reasoning very logically and understandably. I am taking your advice to use the less-suggested SPP4E for a greater margin of reliability (i.e.timer failure).
Thanks for sharing your expertise with us!
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