Outside AC Unit Won't Turn on.

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  #1  
Old 06-23-11, 08:38 AM
T
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Outside AC Unit Won't Turn on.

Hey, I have a little experience with my AC unit because the capacitor blew last year. I'm having a similar problem now. The AC blows but the outside unit never turns on so it's not cold.

I measured the voltages along the way. The voltage from the breaker is good - 2 lines at 120v. The DC voltage coming out of the (transformer/converter?) is no good. It jumps up and down but never makes it past 2 volts.

I want to check and make sure this is the problem and not the capacitor hooked up to it. Was going to ask for a second opinion on this one.

Thanks!
 
  #2  
Old 06-23-11, 11:15 AM
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You've got things a bit wrong, you don't have "2 lines at 120v." but two wires with 240 volts AC between them. Also, the control voltage is 24 volts AC, not DC. If you are using a DC setting on the multimeter then that may be a problem.

Check for about 24-30 volts AC at the coil terminals of the contactor in the condenser (outside) unit. If you have the voltage then CAREFULLY try pushing the contactor contacts to the closed position and see if the compressor starts. If you have the control voltage and the compressor starts when you push the contactor closed you need a new contactor.

If you do NOT get the control voltage then move to the furnace/air handler and remove the blower compartment door. Find the thermostat wiring terminals and while holding the door safety switch in (CAREFUL, there may be line-voltage present on some terminals) check for 24-30 volts AC between the thermostat R and C terminals. No voltage means the transformer or fuse (if present) is blown. If you do get voltage then check between C and Y when the thermostat is calling for cooling. Voltage here would mean the interconnecting low-voltage control cable to the outside unit is damaged.
 
  #3  
Old 06-23-11, 06:19 PM
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i bet ya its the capacitor again. the new ones are not built to last
 
  #4  
Old 06-25-11, 08:56 AM
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No Power to outside unit

I don't have a volt meter at this time to check anything. but if my breaker is good and the air is blowing inside my house but the outside unit is not even turning on then is there something else i can check until i get this volt meter?
 
  #5  
Old 06-25-11, 09:31 AM
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Originally Posted by jmathis79 View Post
I don't have a volt meter at this time to check anything. but if my breaker is good and the air is blowing inside my house but the outside unit is not even turning on then is there something else i can check until i get this volt meter?
this is not your thread, do you have the same problem or have you logged in with a different user name? IF it is not your thread then please post your own as you may have a different problem all together
 
  #6  
Old 06-25-11, 03:43 PM
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Sorry about that i am new to this but yes i do have the same problem.
 
 

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