Hello folks,

I have a problem with my heating and AC unit and was looking for some help. I've done a lot of research on the internet but haven't found anything that worked yet.

First, the other day I tried to turn on the AC and it did not work. I reset it a few times with no luck. I check the circuit breakers and nothing. Then I tried the heat and the fan mode on the thermostat. Nothing. I thought it was a bad thermostat so I replaced it. My original thermostat was battery powered and the new one is house powered. I had to shift the wiring around a little bit (change the G to a C at the thermostat and on the furnace. The NRA n a jumper wire from Y to G on the furnace). I'm almost positive I did this correctly. The power was off at all times when I did it.

When I turned the power back on, the thermostat did not come on at all. I did a little further investigating and check the AC breaker box (I think it's called) on the outside of the house. There was not fuse in it so nothing to blow. I check the main circuit board of the furnace for a fuse and did not find one there either - so again, nothing to blow. My furnace does have a 3AMP CB inside.

Not only is there no power to the thermostat, there is no power to the furnace at all. The LED on the control board are not lit up at all. And I used a multimeter to check power between the R and Y wires. It showed no power at all. I did not check this before I changed out the thermostat but I think this problem existed before I swapped them.

And the obvious, I check the main off switch on the furnace. It's on. I had the safety switch pressed down during my trials. I check the outlet to the furnace blower (it worked). And the CBs are all pressed in (and have been reset more than once).

My only other thought is maybe the transformer went bad on the furnace main control board but that's the only thing I can think off. Let me know if anyone has any ideas. I appreciate the help greatly.

My furnace is a Lennox Elite.

I appreciate any insight.

Jordan

 

I'm not sure how to post pictures on here but the transformer does look a little strange. It is a little discolored and looks polka dotted.

 

Welcome to the forums.

You should check for 120VAC to the service switch on the side of the furnace.

 

PJmax,

Thanks. Here's a picture. I checked the outlet the furnace blower is plugged into and it worked. I'll check the other 120 too.

 

Check for 120VAC to the white and black transformer leads.
If there... check for 24VAC on the two blue wires.

The safety switch must be pushed/held in for testing.

 

Pete,

Disregard previous post if you saw it. With the safety switch in, The switch was showing good power. The transformer showed 120in and about 27out. However, there was still no voltage when I tested the C and the Y or G terminals.

Jordan

 

Test from the hot wire to ground..... switch on.
Should see 120vac there.

 

Pete,

Disregard previous post if you saw it. With the safety switch in, The switch was showing good power. The transformer showed 120in and about 27out. However, there was still no voltage when I tested the C and the Y or G terminals.

Jordan

 

Pete,

Thanks so much. The issue was in the switch I believe. It must've been grounding out or something. It is now working properly with the switch attached but not tucked back into the outlet cover. I'll have to make sure the wires are tucked more carefully as this may have been the problem.I appreciate your help greatly.

Jordan

 

Sounds like a bad switch. I'd just replace it.