My first time trying to troubleshoot an HVAC unit, and I'm stuck. (Carrier 1 ton, can't recall the model number off hand as I'm at work)
If the AC is set to ON, the 3A fuse on my board keeps popping as soon as I push in the "dead man's switch" on the door. If it's off or set to furnace, it's okay.
Blower comes on fine, as does the furnace.
I've replaced the thermostat.
I've checked the wires from tstat to furnace, all fine. No shorts, no discontinuities.
Same thing with the wire from board to condenser, no breaks, no shorts.
Checked the capacitor at the condenser, it responds properly to the OHM meter (goes to 0, approaches infinity).
Cleaned out the contactor at the condenser, a spider made it's home there at one point. But it seems to stay open and close okay. But it never gets the chance to close because the fuse blows before the 24V can hit it.
The contactor has an internal resistance of ~1 ohm.
Transformer is putting out 26VAC, but I figure that's +/- 10% (and with no load) so that's fine.
I'm truly puzzled with this one. Again, it only happens when the Tstat is set to cool. Somewhere there's a short to ground that I'm missing. My guess is the contactor, if I disconnect it from yellow wire from the tstat it won't pop.
Is the ~1 ohm resistance normal for the windings on that solenoid?
[Edited by strawewe on 06-30-2005 at 02:21 PM]