Electric Furnace has me perplexed

[expatriated]

Went over to my sister in laws to replace her thermostat which she said was bad. I looked over the old one and it seemed to be ok but she had the new one there so I installed that one. Furnace didn't come on.

They just moved into this house on Sat. She said that she's not sure if the furnace has ever come on--it has been cold since they moved in.

I checked the breaker box, the control switch on the furnace unit and that condenser float thing a majig. All seem fine. The filter is pretty dirty but nothing that would keep it from turning on at all.

Both thermostats seem to work, i.e., they "click" as if they are making the connection to send power to the furnace but nothing. No air, no sound, no heat, nothing blowing, nothing moving on the outside unit. Just completely dead. I went through the various programs on each thermostat as well as the overrides. They both had fresh batteries and the wiring connections seemed good. And since I tried both of them, I'm pretty sure they aren't both bad. Something in the unit itself.

This unit is approx 6 years old in a single story, new construction home. It's electric, not gas.

She's going to call someone tomorrow since she's renting and the landlord is going to cover it but I'm curious--what could it be????

 

[rickairmedic]

Well the first thing I would do is open it up and check the small fuse 3-5 amp on the control board ( especially if you changed the stat without killing power to the furnace ) . Then if you have a multi meter check to make sure you are getting 220 into the unit and that you have 24 V at the thermostat. The fuse is one just like whats in the fusebox of most cars out there . DONT PUT ANYTHING BIGGER THAN A 5 AMP FUSE BACK IN IF ITS BLOWN and make sure you kill the power before going inside the unit 220 hurts ALOT .

Rick

 

[Grumpy365]

Here is a dumb question.

Did you make sure the light switch mounted beside the unit is turned on?

 

[expatriated]

Thanks, guys. Yes, Grumpy to your question.

Did not check that Rick. I will look into that.

But you guys seem to be on the same path as me--just seems like no power is getting to the unit at all. For whatever reason.

What if the motor on the outside unit was damaged or burned up, what would the inside unit do, i.e., would it noticeably try to turn on or is it a slave to the outside fan motor?

 

[rickairmedic]

The indoor fancoil unit will run regardless of the outside unit running . There wont be a light switch as it is a 220 volt unit . Follow my original suggestions as a start from there could be a bad board or loose wires or any number of other issues.

Rick

 

[expatriated]

(The switch I thought you were referring to was the black switch mounted on the side of furnace. Which I checked was in the on position. )


Well, Rick, thank you. Turns out there were 2 problems--1 was the fuse as you stated, the other was that neither of the thermostats were compatible with the wiring.

Thanks, guys!

 

[rickairmedic]

No problem for future thermostat changes make sure you kill the power to the furnace before touching the thermostat . This will keep you from blowing the fuse . Thermostats run off of a 24v system built into the furnace and if you dont shut the power off first then you will almost guaranteed short out the wires and pop a fuse .


Rick

 

[Frank The Plumber]

You really can't go into these things without a circuit tester and a meter, you need to have a bit of training or a sense of where to start, you need to test out to see that you are getting the proper power to the proper points.

 

[klhitman]

Went over to my sister in laws to replace her thermostat which she said was bad. I looked over the old one and it seemed to be ok but she had the new one there so I installed that one. Furnace didn't come on.

They just moved into this house on Sat. She said that she's not sure if the furnace has ever come on--it has been cold since they moved in.

I checked the breaker box, the control switch on the furnace unit and that condenser float thing a majig. All seem fine. The filter is pretty dirty but nothing that would keep it from turning on at all.

Both thermostats seem to work, i.e., they "click" as if they are making the connection to send power to the furnace but nothing. No air, no sound, no heat, nothing blowing, nothing moving on the outside unit. Just completely dead. I went through the various programs on each thermostat as well as the overrides. They both had fresh batteries and the wiring connections seemed good. And since I tried both of them, I'm pretty sure they aren't both bad. Something in the unit itself.

This unit is approx 6 years old in a single story, new construction home. It's electric, not gas.

She's going to call someone tomorrow since she's renting and the landlord is going to cover it but I'm curious--what could it be????

if she is renting why did she buy a new stat and why did you put it on. that should be the landlords problem. you should send the landlord a bill

 

[DustynF]

Well the first thing I would do is open it up and check the small fuse 3-5 amp on the control board ( especially if you changed the stat without killing power to the furnace ) . Then if you have a multi meter check to make sure you are getting 220 into the unit and that you have 24 V at the thermostat. The fuse is one just like whats in the fusebox of most cars out there . DONT PUT ANYTHING BIGGER THAN A 5 AMP FUSE BACK IN IF ITS BLOWN and make sure you kill the power before going inside the unit 220 hurts ALOT .

Rick

I had that same exact thing happen to me about a year ago when the electronic board went out on our Bryant heat pump. The guy that was working on it couldn't get into the house to change it though but he did tell me how to change it when I got home. Funny... I think his name was Rick as well. I live very close to Louisville btw.

 

[rickairmedic]

Dusty it may very well have been me . I quite often walk customers through " simple " repairs over the phone as I figure when they have a real problem my phone number will be remembered . Yes I do get to Sellersburg from time to time . I have quite a few customers across the big nasty bridge . I lived in Jeff for years before I got the house I am in now.


Rick

 

[expatriated]

if she is renting why did she buy a new stat and why did you put it on. that should be the landlords problem. you should send the landlord a bill

That was my question as well. I'm in Indy, landlord is in NY and my wife REALLY wanted me to (anyone else ever been in THAT position?). It was freezing cold in their house. All I did was try to quick fix the problem last night so it would be warm. I thought it would be much easier as I have done these installations before.

I told her after about 1/2 hour of messing with it to just call someone and bill the landlord. She did after I left. Good thing, too. Because there was a bunch of other stuff wired wrong in the furnace and hot water heater closet so he spent a good bit of time in there straightening out what the owner or whomever had done. I didn't go back to work on it, just found out later what was wrong.

Since you guys on here are such a wealth of knowledge, I figured I'd try to learn something by posting the problem...and I did. I know now how to better attack these things next time.