I have a dead furnace and cannot figure out the problem...I think....I hope I don't know what the problem is. Without complete AS wiring schematics I am guessing on some things which may be leading me down the wrong path.
Status: I have heat pump operation. Last night I had no furnace and I found the breaker tripped in the furnace compartment. Reset and it ran for a test cycle. I now have nothing going on...no lights in the board and no operation. I have 12V
and can make the fan run. I HAVE NO CONTINUITY ON THE TWO BLUE THERMOSTAT WIRES, ON THE HARNESS END OF THE CONNECTOR WHEN THE THERMOSTAT IS SET TO HEAT AND 90*.
I fear this is where my problem is, but I am not sure how the electronic thermostat behaves. An old mechanical thermostat is just a switch that completes the circuit....not sure about this one.
Tests so far: I have continuity on all four of the telephone wires from the thermostat to the A/C unit. The A/C side of the telephone line disappears up into the roof top junction box. There are two blue wires which come back down inside from the rooftop which have continuity when the furnace is commanded on and they are open when furnace is commanded off. They are butt connected to two blue wires which disappear between the curbside skins in a bundle with a lot of other wires. This bundle reappears at the floor behind the microwave. The two blue wires in that bundle are different colors/stripes than the ones at the A/C unit and connect to the furnace connector....but I am used to AS not following any wiring conventions.
When I cut the wires at the furnace connector and at the A/C harness end and run a jumper I can get not continuity on EITHER BLUE WIRE
in the wall and ceiling. This makes me believe I don't understand the chassis wiring harness.
I was of the belief that I have an open in the wall/ceiling in a blue wire....BUT BOTH?
AT THE SAME TIME?????? I find this too coincidental.
I am questioning myself:
What is the wiring routing? What does the thermostat need and to allow the 12V
pass through for the furnace to verify sail switch and limit switch status to the board?
What am I missing?