Heatpump Wiring Issue After Catastrophic Short.

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Jan 25, 2023
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While out of town for a couple weeks last month my heat-pump/blower motor control wiring suffered a catastrophic failure. I'm not exactly sure what went first. Assuming it was the sequencer, it managed to take out the blower relay, the transformer, AND the dual 30A circuit breaker. The plastic innards of the breaker actually cracked leaving it sprung in the on position, forcing the condo's main 150A to trip (it was impressive. It did it again for me when I got home and was trying to figure out what happened).

So anyway, I got the needed replacement parts (subbing the sequencer for a contactor) and attempted to put it all back together again, but it still isn't behaving as it should. First, the diagram on the inside of the unit clearly shows the fan RED wire as "not used", and the fan relay N.C. side jumpered to the N.O. side. In reality, the fan RED was connected to the relay 'Normally Closed' and there was no jumper between the NC and 'Normally Open' (aside from the motor coil itself). In restoring everything I've tried both per diagram and previous reality. Both do not engage the heat side of the heatpump. Connected according to the diagram, the fan only turns on when the aux/electric heat is activated. When the thermostat triggers heatpump heat I can hear the relay flip, but that's all that happens. With fan RED hooked to relay NC the fan doesn't want to turn off.

I've tried to label everything clearly on the pictures. If anyone could offer any suggestions, I'd greatly appreciate it. I have a semi-decent meter (no amp-clamp), if you need me to measure anything. Last details: I have an Emerson Sensi Smart Thermostat and there's a condensate drain float-switch interrupting the RC line (confirmed closed @ 0 ohms).

Thank you!
First off welcome to the forum.

Your problem is a little above my pay grade, but will give you a bump and we have few folks here that should be able to offer some help.
Thanks @bud16415 ,
I hope so! Thankfully I'm in Southern Nevada, so it's not too cold inside (55~60). Unfortunately, having an electrician install the replacement breaker, plus buying parts, brought me to my spending budget for the moment, so hopefully someone can offer some advice!
It has center taps on the primary, so it can be either. I get 28V out from it when completely unloaded (but I'm actually putting 248V into it - my power is a little hot here). When loaded, it's closer to 24V.

I reconnected the fan red line to the relay's normally-closed -- as it had been initially -- and it seems to be working now.