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cannon man · 01-20-2017, 10:49 AM

from reading in here it looks like the power comes from the battery control center. well, lots of gizzmoses in there. any one know witch one is for power to thermostat? would it be a cb or a fuse?
thanks for help. its cold here!
dave

Skip426 · 01-20-2017, 11:05 AM

Should be a fuse , maybe as low as 5 amp.
Do you have a 12 volt test light or a voltmeter?

Skip426 · 01-20-2017, 11:10 AM

I have this document on BCC's don't know if any of the info will be of any help though.

cannon man · 01-20-2017, 03:03 PM

thanks skip426.
i saved the doc will study it tonight.
yes i have a test light and a meter.
whats next?
thanks, dave

Skip426 · 01-21-2017, 11:04 PM

Sorry for the delayed reply .

Next would be remove t'stat from the wall to see if it is getting 12v + power .
Disconnect then reconnect the wiring after 30 sec to see if the t'stat was just locked up.
If no power then you'll have to start testing every fuse for power in and out ; remember " looks good " isn't good enough , fuses must test good.

If you have battery power to the t'stat, and it still doesn't work , post the brand and model, maybe your furnace info too.

and we'll see if we can find a wiring diagram, to see if there is a ground wire that needs testing.

Tahiti16 · 01-22-2017, 09:17 AM

One I found on my 06 just inside the outside cover is a "switch" which is also circuit breaker. It's purpose is disable unit while servicing, mine was bad. Didn't trip but wouldn't past voltage.

Quick check short leads together does thermostat power up?

cannon man · 01-22-2017, 10:35 AM

thanks again
used a ground buss to check for power in the harness. nothing.
outside cover? you mean the basement door to the heat pump?
will try to find reason for loss of power. if no joy ill run a new hot wire. hope that will wake it up. will check to see if it has a good ground and go from there.
can't get to m/h till later this week.
i'll be back
dave