(System is straight cool, 10KW 1-stage heat.) Just installed this variable speed air handler with a matching 12-SEER Am Standard condensing unit. All works well in cooling mode (soft start, 1/2 speed for 7 1/2 minutes, etc.)but air handler will not start in heat mode. Wired correctly, has 24-volts at the W-1 terminal, but the heat contactor will not pull in and the blower motor sits idle. Passes all tests using the factory "Trouble Shooter" circuit board and 4-wire test cable, and all connections/connectors appear to be well made. When a jumper is momentarily connected from the common side of the heat contactor to the common on the low-voltage terminal board, the contactor pulls in (but the blower remains idle). Anyone had a similar problem...fix?
Regular Trane air handlers require the stat to bring on G with a call for heat. Maybe this one does too. Someone pointed out a while back that if the blower isn't energized, a relay breaks W1 between the terminal strip & the contactor.
Bald is right, need to have G connected from AH to stat. My only question is why you would want a variable speed AH with a straight cool system.
These guys are right in telling you that G needs to come on with W and is normally done with a trane stat or a stat that you can setup for electric heat this way by changing a setting. Common for the heat contactor is switched through the blower control.