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View Full Version : How to tell if AC start relay is bad?


tkjazz
Apr 25, 2009, 01:11 PM
Our central ac unit is blowing air, but the motor is not kicking on. The start relay clicks when you turn on the termostat, but the fan doesn't turn, nor does the motor hums. How can you tell if a central ac start relay is going bad? Also we have purchased a new fan motor, and decided to change the capacitor and run capacitor, our old fan motor had 5 wires (brown, black, purple, orange, and yellow); the new fan has 4 wires (brown, white, black, brown-white, ground). We know where all of the wires connect other than the white wire, which is the common wire? Where do you connect the common wire? Here is a wire diagram for the new fan motor:

Black-HI
Brown/White- 370 VAC
White- Common
Brown-Capacitor

Can you tell me where to connect these wires to make sure we have them connected properly. Can't afford a tech, so I have to make it work!


The different colors of the wires of the new fan motor is confusing us!

Thanks

Stratmando
Apr 25, 2009, 02:19 PM
A couple of good AC guys here, I would wait to hear if Capacitor connects to the 2 browns, and 240 to the white and the black.
Look on the Motor Nameplate for a very small diagram.
If 24 volts is present to coil on contactor, it should energize and have 240 volts on Load side, if 240 volts is present on the line side of contactor.
I think the old motor had 2 wires that can be swapped to reverse rotation(Purple and brown?)

T-Top
Apr 25, 2009, 08:47 PM
Is this the out side condenser motor or indoor blower motor your working on(240 volt or 115 volt)? Brown/white and brown go to the run capacitor, white is common and black to the contactor or relay.

wildwilly7758
Aug 11, 2013, 06:42 PM
I have a colman roughneck ac. It makes a little noise and blows cool air.then the nois quits and blows just air out.then it will start making the noise again and starts blowing cool again.could that be a starting relay? Or is it getting ready to go out?

Stratmando
Aug 11, 2013, 06:52 PM
Not sure the Type AC you are talking about, the outside unit will have a compressor and a fan, sound like the compressor is what your talking about? Capacitor and compressor connections are about all that is servicable. Work Safe.