A/C won't stay running


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Old 08-12-09, 04:39 PM
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A/C won't stay running

My air conditioner only works spuraticly I'm wondering what switch is not letting it turn on: pressure switch or some other safety switch. I replaced contactor and still only works ocassionally. I'm getting 24 volts to unit so I know its not tstat. What are the two 24 volt wires going directly into top of compressor? What is the humming small box conected to the small copper tube where it goes into the furnace? What is a small circuit board that the 24 volt wires connect to on the a/c unit? Need help, thanks.
 
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Old 08-12-09, 04:57 PM
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My guess the small circuit board in the condensing unit is a delay timer designed to keep the compressor from short cycling. This could be verified by the wiring schematic. I have replaced several timer boards due to failure.
The two wires to the top of the compressor could be a thermal overload. This could also be verified with the schematic. If the overload is opening you may need to have some professional service, could be a low charge.
The box on the line at the furnace could be a solenoid valve. Pics would help if you could post some.
Model and serial #s could also help.
 
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Old 08-12-09, 07:12 PM
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Model and Serial

The air conditioner is a Bryant Model 563an036-a Serial# 2094e18144. The yellow wire coming off the circuit board on the ac unit(compressor time delay) T1 Terminal has 24 volts when tstat set to cool. But the purple and black T3,T2 don't register volts when ac unit stops working.
 
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Old 08-14-09, 11:24 AM
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Bypass the timer board by connecting the yellow wire directly to the contactor coil. Connect to the coil terminal that is not being used as the common. The common is usually a brown wire connected to one of the small thermostat wires going into the house, usually ran with the refrigerant tubing. The yellow wire is probably connected to another thermostat wire going into the house. this will be connected to the opposite coil terminal as the common. Wiring this way will take the timer out of the circuit. If the unit still doesn't work properly the board is probably ok.
 
 

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