Problem with 24 Volt control circuit


Old 06-27-07, 10:59 PM
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Question Problem with 24 Volt control circuit

Just installed a used Ruud Achiever 10. Everything works ok except the contactor switch and reverser valve don't engage correctly. When the unit is turned on, the contactor switch vibrates but won't engage until I press the switch closed with my finger. Then everything works fine. The reverser valve comes on in heat mode (I believe Ruud uses air conditioning as the default mode) and won't switch to air conditioning unless I rap on the reverser valve with a screwdriver handle. The transformer is putting out 27 volts and I am getting 27 volts into the outside unit, but the contactor switch reads 19 volts across the 24 volt terminals, while the reverser solenoid reads 7.5 volts across after it engages, which, as I understand it, should be almost zero. Can anyone think of what could be causing this? Thanks.
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Old 06-27-07, 11:27 PM
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First it's used, Someone had a reason to get rid of it.

next Rheem/Ruud Reversing Valve is in defaulted in cooling mode with no volts to the solenoid

You shouldn't be getting any volts. Did you wire up your thermostat correctly?
B terminal. if its an O/B terminal and digital you will have to program the thermostat for the B terminal.

You can always take off the reversing valve thermostat control wire, So no volts would be going to the solenoid.

Next something is drawing your control voltage, since you only have 19v on your contactor coil. it could be because everthing is wired up wrong. Or you have a bad device like a time delay sucking up the control power.
Old 07-01-07, 08:08 PM
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Smile Problem fixed

Problem is fixed. The AC tech's helper had wired a common wire with wire from the B terminal. Ruud's common circuit is through the brown wire, and they said most brands use the blue for common at the thermostat. Some voltage was evidently being redistributed through the common wire. Now all voltages are just what they are supposed to be. Thanks Dave.
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