No power to thermostat

[Alliecaet]

So I decided to upgrade the thermostat and now have no power to the thermostat. I've tried 3 different thermostats. Red (12v Pos.) wire connects to RH, Green (High fan) to G. White (heat) to W, Y (Compressor) to Y and nothing works. I also have a Grey (Lo Fan) and Blue (12v neg). I cannot get either the heat or the a/c to come on. When we test each of the wires none show hot. We have no fuses that we can find that are blown.

Any help please?

Thanks in advance
T

[Grumpy]

Gently pull the hot wire out as far as you can. Sometimes there is another in-line fuse .

[norty1]

I will bet there is a blown fuse somewhere.

I blew one when I changed mine out but racking my brain I can not remember where it was located.

A buddy was changing out his analog to digital and fried the new thermostat by reversing the 12v dc wires so be careful when you get the voltage back.

[mike837go]

First double-check that the always hot lead is dead vs. ground using a VOM or DVM.

[Jagiven]

Try connecting the two wires by hand and see if the furnace starts.

If that does not work, remove the cover on the furnace. Your furnace might be different than mine, but behind the metal cover is a reset switch, flip it and see if that helps.

Do you know the make and model furnace you have?

[Grumpy]

Just reread your post.
Thermostat (Coleman) should be
White from thermostat to blue for furnace
Blue from thermostat to white (RV ground)
Red to red
Yellow to compressor
Grey to low fan
Green to high fan

There is also a blue in the a/c wiring cable that goes to white.

[Alliecaet]

Thanks everyone. I'll look into these and come back with answers/ for more help. I have called a professional but they haven't called back yet.
Yes for sure there is no positive wire. We've checked them all. I pulled the circuit board from the a/c and I get power to the circuit board but I can't find where it's supposed to come out from.. But I didn't think this would affect the heat. I'm thinking blown fuse too but can't find one. I'll pull out the wires farther. I have 3 thermostats so if I ruined the first one, one of the other two should still be working. I would think. Oh, I even tried to reconnect the old thermostat and it's not working either. So now that's 4 thermostats.

[mike837go]

If you've got no always hot lead, you've got to troubleshoot the RV's wiring to get that established first!

[Alliecaet]

Thanks everyone!!! I don't have free internet here. I blew the circuit board, replaced that, picked a thermostat from the 4 I had pushed the reset switch on the furnace and all works GREAT!!!