Electric furnace not functioning. Neighborhood had some power hiccups yesterday when there was heavy wind.

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
Nothing in the house went without power for more than a couple seconds, but it happened many times in a 10 minute period. I checked the circuit breaker panel in garage, all the breakers are in the ON position, and just for the hell of it I flipped the two furnace breakers a couple times each to be sure.

Furnace is a ARUF 14 Air Handler. It doesnt say that anywhere on the unit, its what the manual says, and I have no reason to disbelieve it right now. Am looking thru the booklet for troubleshooting help but there isnt much. If I call the furnace tech on a weekend its gonna cost me triple the normal rate.

The Honeywell thermostat upstairs functions when I installed the batteries in the back. Without batteries it gets no display, so I guess power is not going from the air handler up to the thermostat. Normally it has no batteries installed, and most of the techs who came by told me to leave the batteries out during normal operation.

What information do I need to start troubleshooting? I own hand tools and a couple of multimeters.
 

drnickriviera

Platinum Member
Jan 30, 2001
2,418
205
116
First thing i'd check is the fuse on the control board. You'll need to remove the bottom door that covers the blower. (Unplug unit first even though there is a switch inside that cover, and you may need nut driver to take the door off) Should be able to see the control board then. They usually use a normal automotive ATC fuse

Edit. err well after looking at the manual, it can be up or down flow, so it may not be the bottom door. Pics would be good
 

Greenman

Lifer
Oct 15, 1999
20,920
5,543
136
There should also be an external fuse near the unit. Generally it's an SSU.
Beyond that, I've got nothing. Never dealt with an electric air handler.
 

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
IMG_20211128_150336_1.jpg


Could not find a fuse. Found two breakers. They are both in the ON position, and again I flipped them a couple times to be sure.
 

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
There should also be an external fuse near the unit. Generally it's an SSU.
Beyond that, I've got nothing. Never dealt with an electric air handler.

Will look for that next.


OK, checked the internet for pics of SSU. There is none by the furnace. And theres no plugs either. Its hard wired directly in to the ceiling, and I dont feel like ripping apart the ceiling just yet.
 
Last edited:

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
246 volts on inputs and outputs of both breakers. There were several board in the unit, I will see if I can find a fuse. Allegedly an automotive fuse, which is good cuz I have a big fuse pack in my cars tool kit.
 

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
Found the fuse on the big board in the right hand side. Took it out.
Ohm meter says it had infinite resistance. Problem solved.


THANKS GUYS!!!!!!
 
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shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
God dammit!

The new fuse sparked and melted immediately. Clearly there is something else going on here.

I flipped both breakers and put the panel back on. Will have to call the repair guy tomorrow.
I can use plug in heaters for now. They're expensive, so I need to be frugal. But they work.
 

bbhaag

Diamond Member
Jul 2, 2011
6,885
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I see there is a loose blue wire cap in the pic you posted. Are there any exposed wires grounding out on the unit because a cap fell off?
 

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
I see there is a loose blue wire cap in the pic you posted. Are there any exposed wires grounding out on the unit because a cap fell off?
No, I checked. It was just a cap the previous guy didnt feel like picking up.
 

herm0016

Diamond Member
Feb 26, 2005
8,447
1,070
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Could be the 24 volt transformer for the thermostat. check the resistance of each side of the transformer, should be a few ohms and not a dead short.
other than that, you are probably looking at a control board. good luck.
 

shortylickens

No Lifer
Jul 15, 2003
80,287
17,079
136
No the control board itself was fine, in fact everything inside the house was fine.
It was outside. Inside the radiator there are wires and one of them somehow shed a bit of insulation and touched a copper tube. The short indirectly caused the fuse melting inside the house, on the control board.
Interestingly that was the same problem two years ago except it was even worse because it caused the circuit breaker in the garage. Builder grade breaker. Needed replacing, but by a certified electrician who arrived two days after the furnace was fixed.
 

herm0016

Diamond Member
Feb 26, 2005
8,447
1,070
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No the control board itself was fine, in fact everything inside the house was fine.
It was outside. Inside the radiator there are wires and one of them somehow shed a bit of insulation and touched a copper tube. The short indirectly caused the fuse melting inside the house, on the control board.
Interestingly that was the same problem two years ago except it was even worse because it caused the circuit breaker in the garage. Builder grade breaker. Needed replacing, but by a certified electrician who arrived two days after the furnace was fixed.

next time tell us it's a heat pump, I assumed "electric furnace" was resistance heat.
 
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