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mint5jf
Jun 6, 2008, 06:53 PM
I've got a problem I need help with. I just installed a condensing unit outside for my air. It was empty when I got it. No refridgerant. When I start the unit the fan and all comes on but the compressor does not. This is a duroguard 2.5 ton unit. I have tried to boost it and still no luck. The unit is only 1 year old. Is there any way anyone can help me troubleshoot this thing and help me solve it. I have all the tools I need (gauges, vacuum pump,freon,etc.)
Please helpl its so hot in the indianapolis area.

Stratmando
Jun 6, 2008, 07:30 PM
First, make sure you have power in and out of disconnect(240 volts?), then for outside unit to kick on you need 24 volts from AHU, Transformer and thermostat to provide 24 volts to contactor. If no 24 volts to contactor coil, it is a control problem, Contactor can be manually overridden for testing, to check compressor operation.

mint5jf
Jun 6, 2008, 11:07 PM
OK here are my thermostat wires so I can make sure I have them right.

Furnace colors-
Red
White
Grey
Brown

Thermostat wires-
Green
Blue
White
Red

Ac unit wires-
Red
White

Please confirm for me that I have them right by telling me which wires go where.
Thanks so much

Stratmando
Jun 7, 2008, 06:12 AM
On thermostat (R)red is 24 volts from transformer, (W)white is Heat, Green(G) is Fan, Yellow or blue is cool. A multimeter will confirm switching of thermostat,
When set to cool, red connects to Yellow or blue(verify)for the compressor contactor, and also (G) green for blower motor.
In Heat, red connects to (W)white for Heat strip contactor and (G) for blower motor.
When set to Fan only, red connects to (G)green/blower motor only.
Yellow or blue will connect to red or white for Compressor, other wire(white or red connects inside Air Handler(other secondary wire from transformer).
Since wire colors are different, use gray for green, and brown for blue, then red is red and white is white.