HVAC Compressor Contacts Wiring???? - HVAC - DIY Chatroom Home Improvement Forum

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Old 05-28-2010, 11:13 AM   #1
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HVAC compressor contacts wiring????

Ive tried searching all over the internet to find any kind of help figuring this out so hopefully somebody on here can help me out. My central AC stopped working the other day. I checked the circuit breaker and found it had tripped. It had done this once before and the AC worked fine after reseting it so i just reset the breaker again. This time, nothing happened. The air handler and condensor fan operate but there was no compressor operation. After some basic inspections of the unit i found the 3 wires leading into the compressor itself were heavily corroded and appeared to have shorted to one another, causing them to melt and burn off of the terminals. The wires are red, black, and purple. The red and black wires being a slightly bigger gauge wire. The wires may be for the capacitor, Im not sure. My problem is that the wires were no longer attached to the terminals so I dont know where each wire go. Im an automotive mechanic so while I have a general idea of how the system works, Im not sure exactly how things are wired up for home use and how the system will react if its wired incorrectly. Ive searched all over for anything to show me how these wires go. The terminals are 3 wide, flat male terminals with one on top laying horizontally and two on the sides laying vertically. Almost in a triangle shape. Any help would be greatly appreciated. Even if its just a link to something helpful. Thank you in advance.

p.s. The house was empty for 5 yrs before we moved in last fall so I dont really know what issues it had before we moved in, how old the system is, what has happened in the mean time, etc. Im just hoping correcting the wiring will fix the problem as its getting quite hot here.


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Old 05-28-2010, 09:50 PM   #2
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Do you have an ohm meter?

Turn off the breaker...
Start by ohming each compressor terminal to ground, to verify that your compressor is not DOA.

The 3 terminals are: C (Common) S (Start) and R (Run).

These letters are usually displayed by the terminals or on the terminal cover.
Your wiring diagram will tell you which color wire is Common, Start, and Run.

After you determine that your compressor does not have a direct short to ground, and you determine which terminal is C, R , and S, you should use a TermLock kit of some kind to reconnect your wiring.

You can us an ohm meter to determine the function of each terminal...

C is usually at 9:00, with S at 3:00, and R at 6:00 but this varies so you must verify it.


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