Newell Gurus

Full Version: A/C wiring question
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
I am planning to use this motor for the condenser fan. It has a run capacitor but I don't see a start capacitor. Should I wire it into the capacitor that is already mounted to the condenser box or just wire directly to the 115V or is there a better way to do it?
What size is the existing capacitor? According to the nameplate this motor requires a 3 mfd. the motor requires the cap
The capacitor that came on the motor is a 7.5 mfd. I think the condenser cabinet has a 20+7.5 I'm assuming that is the start cap for the fan, and a 88-108 that I would think is for the compressor. There is another small round component that is wired into the capacitors as well.
Heres a pic
Sorry. It’s been a while since I was in one of those units. The existing motor does indeed have a run start cap. The little black thing is an old school thermal interrupter that takes the start side out of the cap when it heats up.

I would wire the new motor into the existing setup and test before reinstalling
I apologize for providing wrong information. I pasted the pic of the motor from fleabay not realizing the label was different than the motor I received. The new motor I received has a 7.5 Mfd capacitor bolted to the side of it. It appears to me that I should be able to wire it direct to 115. It has run that way on the bench drawing .9 amp running with no load.
If I understand this correctly the black capacitor (88-108 mfd) functioned as a start capacitor for both the compressor and the fan motor. The thermal interrupter only controlled that cap. The silver cap (20+7.5 mfd) functioned as the run capacitor for both the compressor and the fan motor. I am unsure of how to wire the remaining two capacitors and the thermal interrupter in to the compressor. Would there be a problem with wiring new motor (and its 7.5 mfd capacitor ) in with the existing capacitors the way the old motor (which did not have its own capacitor) was? That would then provide a starter cap and an additional 7.5 mfd cap to the new motor which it may not require or tolerate.
(06-20-2018, 08:59 AM)HoosierDaddy Wrote: [ -> ]I apologize for providing wrong information. I pasted the pic of the motor from fleabay not realizing the label was different than the motor I received. The new motor I received has a 7.5 Mfd capacitor bolted to the side of it. It appears to me that I should be able to wire it direct to 115. It has run that way on the bench drawing .9 amp running with no load.
If I understand this correctly the black capacitor (88-108 mfd) functioned as a start capacitor for both the compressor and the fan motor. The thermal interrupter only controlled that cap. The silver cap (20+7.5 mfd) functioned as the run capacitor for both the compressor and the fan motor. I am unsure of how to wire the remaining two capacitors and the thermal interrupter in to the compressor. Would there be a problem with wiring new motor (and its 7.5 mfd capacitor ) in with the existing capacitors the way the old motor (which did not have its own capacitor) was? That would then provide a starter cap and an additional 7.5 mfd cap to the new motor which it may not require or tole
capacitors in parallel are like resistors in series so that motor would have 15 mfd of capacitance. should be with in +10% -20% so just put 110 v to that motor. the 88-108 mfd is start capacitor for compressor only
Dean

I just don’t know without a schematic of the system
I got the A/C together and functional today! The new motor I installed was the same model that had been used as a replacement  by another Guru a while back. I'm slightly concerned that the new motor is rated at 1/10hp and the original motor was 1/6hp but the good news is that the new motor contains ball bearings instead of bushing bearings as in the original. I am posting a pic of the motor box label and the motor installed in the blower housing. I had to make a few modifications. The motor shaft had to be shortened by about 5/16 inch, the new motor has it's run capacitor mounted to the side of the motor. I remounted it to the outside of the blower housing for more clearance in the air inlet. I eliminated the (brown)wire that connected the original fan motor to the A/C case mounted capacitor. The black and white 115V wires connected as before.
Thanks to Richard for offering the best help he could considering my inability to describe the problem properly or supply accurate facts.....