[eball]

He guys/gals,

My heater stopped working a week ago. Its a 2008 honeywell system.
AC works fine.
Main blower come on with heat request. heat sequence never starts.
Pressure switch is fine.
But the inducer never starts.

I powered the inducer straight to a 120v plug and it runs fine, no bearing or jamming issues.

I am not getting power from the mother board to the inducer. The rest of the board has power. I checked the terminals on board for the inducer and have good continuity but I am not getting power. I pulled the board off and checked the back for solder joints. Everything 'looks' good. no breaks or burn marks etc.

After everything i have read and tested, i am at the conclusion it has to be the mother board (maybe one of the relays or something)

Does that sound right? Any help would be greatly appreciated.

 

[yuri]

As long as you have 24 volts from W to C at the board the inducer should start. The relay for it may be shot. Try gently tapping on the black plastic relays. Still would need a new board as tapping won't fix it.

 

[user_12345a]

Check the high limit switch - if it's stuck open any modern furnace will behave as yours is, not sure if a call for heat is needed or not.

Check for error codes.

If all the safeties are fine, the connections are fine and the board is not applying power to the inducer with a call for heat, yes the board is bad.

 

[eball]

As long as you have 24 volts from W to C at the board the inducer should start. The relay for it may be shot. Try gently tapping on the black plastic relays. Still would need a new board as tapping won't fix it.

No volts at W/C.
I am getting 24V straight off transformer.

 

[eball]

Check the high limit switch ....
Check for error codes.

No error codes.
Not sure how to check high limit switch?

 

[eball]

Ok, just checked limit switch. Read 0V between terminals.

 

[Bitters]

If you have 0 volts on W/C when the stat is calling for heat, then you have a stat or wiring problem.

Also check R/C.

 

[eball]

If you have 0 volts on W/C when the stat is calling for heat, then you have a stat or wiring problem.

Also check R/C.

i have 24V on R/C and G/C.

nothing on W/C or Y/C.

 

[roughneck]

i have 24V on R/C and G/C.

nothing on W/C or Y/C.

You should have 24 v between Y/C and W/C when the cooling or heating is calling only. Or else those things will not run.

 

[eball]

If you have 0 volts on W/C when the stat is calling for heat, then you have a stat or wiring problem.

Also check R/C.

AHA!!!

We recently switched our thermostat. The W wire had slipped out!!! :vs_mad:
Didn't occur to me since everything else was working.

Thanks boys for the help!:biggrin2:

 

[yuri]

Glad you got it fixed.:vs_karate:

We always start with the obvious before replacing expensive boards.:wink2: