A/C and fan inop..help!

[Iraqvet05-JAY]

Camping this weekend and the air conditioning and fan are not working. I installed a Honeywell thermostat last time we camped and it worked then. I swapped the mechanical Coleman thermostat back in but the same problem persists. I probed the A/C breaker and I'm getting power there. What's do I look at next?

 

[Grumpy]

Are you getting 12v to the thermostat?

 

[Iraqvet05-JAY]

Are you getting 12v to the thermostat?

Just checked white/blue (-) and red but getting nothing.

 

[Grumpy]

Check the 12v fuse for the a/c & furn

 

[Iraqvet05-JAY]

Fuse panel says fridge and furnace are on the same fuse but the fridge runs on gas. No fuses visibly blown.

 

[Iraqvet05-JAY]

I can't determine why the red wire has no voltage or where it goes . Any harm in running a hot 12v jumper wire from a light to the thermostat just to get it voltage or an I asking for trouble?

 

[klpoppe]

I think I read on here once before there may be an inline fuse on the thermostat wire somewhere near the thermostat. I may be wrong but worth a try...

 

[Iraqvet05-JAY]

I pulled lightly on that red wire but found no fuse in the wall cavity. I ran a jumper wire from an adjacent ceiling light to to thermostat and have A/C now but I still need to trace that wire...maybe to the furnace?

 

[RedHorse1]

Maybe a continuity test from the thermo to the fuse to verify a break in the wire.

 

[Iraqvet05-JAY]

Maybe a continuity test from the thermo to the fuse to verify a break in the wire.

Unfortunately that wire doesn't run directly to the fuse panel.

 

[klpoppe]

I pulled lightly on that red wire but found no fuse in the wall cavity. I ran a jumper wire from an adjacent ceiling light to to thermostat and have A/C now but I still need to trace that wire...maybe to the furnace?

Does the furnace turn on when you set it to heat with the thermostat hooked up to the jumper wire? I would imagine the red wire would be supplied by the furnace considering that is a 12volt device. If the furnace not working may need to be reset? - that may fix the problem of no power to the thermostat. Can't say for sure but grasping for straws at this point!

 

[abarkl]

If the thermostat connecting wires are solid copper there's probably one that's broken but can't be seen beneath the coating. Strip back more coating and check, use the pin point of some tacks for your DVM leads and double check for continuity on each wire.

 

[Iraqvet05-JAY]

The wires are stranded. The furnace does not work with the temp power wire feeding the thermostat. I believe the furnace is not getting power which in turn should feed the thermostat. The furnace in this TT is buried under the sofa. I need to remove the sofa and pry off the luan cover to check there.