justincaseme
Dec 22, 2008, 01:52 AM
Over the summer my mechanical thermostat broke and I replaced it with a White-Rogers 1F78 (digital). I thought this was going to be easy, but in a long process of trial and error the furnace fuse blew several times. Finally we got the heater to work, but when we'd turn on the A/C, the fuse would blow. Eventually we got the A/C working, but then turning on the heater would blow the fuse... very frustrating... we stuck with the A/C since that's what we needed at the time.
Well it's winter now, and we really need the Heater instead. Having both the heater and A/C wired correctly would be great :) I can't figure out where I'm going wrong with the wiring. I've checked the manuals for both the heater and the A/C. At this point, I can't even be sure if it's the wiring on the furnace end, the thermostat end, or both, that's screwed up. Here are some pictures of both the furnace end wiring and the thermostat end wiring. Any help?
Thermostat Manual (http://www.rosemarydrive.com/renovation/hvac/thermostat_manual_0037-6614.pdf)
Installation Manual Part 1 (http://www.rosemarydrive.com/renovation/hvac/installation2_im-pg8j-10.pdf)
Installation Manual Part 2 (http://www.rosemarydrive.com/renovation/hvac/installation_im-pg8j-05.pdf)
I know the PCB labels are tough to read. So I've tried to clarify them where needed with purple text.
FURNACE END WIRING
On the picture of the Furnace end, the white and red wires at the top connect to a pump for removing condensation (I believe).
The purple 3-amp fuse to the right is the one I've blown many many times.
http://www.rosemarydrive.com/renovation/hvac/furnace_end1.png
THERMOSTAT END WIRING
Notice how RH and RC are jumpered together by the manufacturer. I don't know why that is.
http://www.rosemarydrive.com/renovation/hvac/thermostat_labels_clarified.png
Well it's winter now, and we really need the Heater instead. Having both the heater and A/C wired correctly would be great :) I can't figure out where I'm going wrong with the wiring. I've checked the manuals for both the heater and the A/C. At this point, I can't even be sure if it's the wiring on the furnace end, the thermostat end, or both, that's screwed up. Here are some pictures of both the furnace end wiring and the thermostat end wiring. Any help?
Thermostat Manual (http://www.rosemarydrive.com/renovation/hvac/thermostat_manual_0037-6614.pdf)
Installation Manual Part 1 (http://www.rosemarydrive.com/renovation/hvac/installation2_im-pg8j-10.pdf)
Installation Manual Part 2 (http://www.rosemarydrive.com/renovation/hvac/installation_im-pg8j-05.pdf)
I know the PCB labels are tough to read. So I've tried to clarify them where needed with purple text.
FURNACE END WIRING
On the picture of the Furnace end, the white and red wires at the top connect to a pump for removing condensation (I believe).
The purple 3-amp fuse to the right is the one I've blown many many times.
http://www.rosemarydrive.com/renovation/hvac/furnace_end1.png
THERMOSTAT END WIRING
Notice how RH and RC are jumpered together by the manufacturer. I don't know why that is.
http://www.rosemarydrive.com/renovation/hvac/thermostat_labels_clarified.png