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View Full Version : How to wire outside A/c unit to furnace


jbalk
Apr 3, 2010, 08:14 AM
We installed a new goodman gas furnace last fall and it has run perfectly all winter but for the first time this spring I started the cooling system and the outside cooling unit must be wired wrong because the outside compesssor fan comes on but the pump dosen't start . Only warm air flows in the house. Two wires go out to the outside compressor. I have a 4 wire thermostat.. I connected Y from the thermostat to the Y terminal on the furnace and the Y on the furnace to one of the two compressor wires. I connected the other compressor wire to C on the furnace wireing block. There is no C on the thermostat. I can't distingush between the 2 Outside unit wires accept that they seen to go to relays out there

Joshdta
Apr 3, 2010, 09:04 AM
The 2 outside wires go to y and c at the furnace just as you have it. May be a bad start compasitor keeping the compressor from running.