home hvac problem / question

[Soundguy]

Trane unit, compressor outside, air handler in garage, etc. Unit runs on cool fine, shift to heat, and shortly the digital thermostat goes blank, and a 5a fuse blows in what appears to be a 24vac transformer circuit near a big relay in the air handler.

I'd just like to sound Intelligent when I call the repairman, vs like a sheep. Don't want him to tell me my turbo encabulator is bad and i need a whole new unit

History: Unit 15 ys old, otherwise ok shape. Filter each month, has had checkups every couple years. Has been thru 1 cap and fan motor outside, plus had the a coil removed and cleaned once after a cheap filter disintegrated plugging a coil. Ac comes right on, cools good.

Thanks for some ideas

 

[Professor Marvel]

I believe the major change from heat to cool in a heat pump is just the reversing valve. is that in line with the fuse that blows? It is a solenoid control. But I think Trane releases it for heat. IE in needs to be energized to cool. To eliminate it unwire it and put it in heat and see if it still trips. How cold is it there? Is it possible it is cold enough for your electric backup/emergency heat to be coming on?
Does the compressor come on before it trips?

 

[davesl708]

My first thought would be to look at the thermostat for proper functioning. If you are familiar with a multi-meter shut off power and ohm the transformer to see if it is shorting out.

 

[arlen4720]

Trane unit, compressor outside, air handler in garage, etc. Unit runs on cool fine, shift to heat, and shortly the digital thermostat goes blank, and a 5a fuse blows in what appears to be a 24vac transformer circuit near a big relay in the air handler.

I'd just like to sound Intelligent when I call the repairman, vs like a sheep. Don't want him to tell me my turbo encabulator is bad and i need a whole new unit

History: Unit 15 ys old, otherwise ok shape. Filter each month, has had checkups every couple years. Has been thru 1 cap and fan motor outside, plus had the a coil removed and cleaned once after a cheap filter disintegrated plugging a coil. Ac comes right on, cools good.

Thanks for some ideas

Is there a schematic in the door? If so, take a picture of it and post it.
The reversing valve would be a good place to start, if it's sticking, the solenoid would over amp. Most of them de-energize to heat, but some in the southland energize to heat.

 

[merlynr]

Can you go to emergency heat only?

 

[murphy1244]

My first thought would be to look at the thermostat for proper functioning. If you are familiar with a multi-meter shut off power and ohm the transformer to see if it is shorting out.

That would be my first check too and the wiring that completes that circuit.

 

[swnoel]

Could be a chafed wire or bad solenoid... any rodents enjoying a warm motel room in your condenser?

 

[davesl708]

View attachment 409671

Here is a problem I had with the outside unit. Have since replaced HVAC with geothermal ground loop.

 

[Looking4new]

Soundguy, your thingamajig is shorting out the whatchamacallit and it will cost you mega bux to replace with a new unit that will only last about a year or so with its' lifetime warrantee. (Whos lifetime?) The lifetime of the faulty parts installed to begin with.

Seriously, I would look at the thermostat first.

 

[merlynr]

Hey daves1708, I just replaced that relay(contactor) on my heat pump a couple of months ago. Fairly easy fix at $28.

 

[Ken]

Sound guy Look at the board in outside unit it should have a diagnostic mode and uses flashing lights to tell of problem . usually relay failure. Replacement board use your reference book for address and mailed from Memphis Tenn.
Worst decision I've made was not to replacing my Trane but was talked into using a Brand X after it was hit by lightening. Never knew when Trane was running. This replacement sounds like sitting in front of Cessna air plane.
ken

 

[Soundguy]

Well, had to go back to the Dr this am, think my pneumonia is comming back.

May have to leave this one to the pro's Not up to taking the outside unit apart right now.

Either i'll just let it set a bit till i can do it or i'll call.

it's not cold enough in fl to need heat now, and the ac works fine.. so it can set a few days easy..

 

[newbury]

Be sure to read rswyan's travails on home furnace repair.

Hope you have good repair guys.

 

[davesl708]

Hey daves1708, I just replaced that relay(contactor) on my heat pump a couple of months ago. Fairly easy fix at $28.

I just had to remove the dead mouse that was blocking the contacts. (look close at pic)

I replaced the unit because it was 30yrs old and expensive to operate. The Geo system cost very little to cool the house and half what it cost to heat. Plus no noisy outside unit.

 

[Soundguy]

Update, contact or, plus found the wire diagram, and the fuse was undersized, both fixed now, think that was about a 10m job once started

Thanks

 

[Dave M7040]

Be aware that sealed contactors are available which will solve all sorts of problems from lady bugs, ants, rodents getting into what you have and causing problems.
SureSwitch
There are many places which sell them. Installation is not complicated. Getting one with the correct coil voltage is critical.
Dave M7040

 

[Soundguy]

yup, corect coil voltage and a good unit was purchased. and it was more spendy than the amazon 45$ jobs too.

 

[arrow]

Sound guy Look at the board in outside unit it should have a diagnostic mode and uses flashing lights to tell of problem . usually relay failure. Replacement board use your reference book for address and mailed from Memphis Tenn.
Worst decision I've made was not to replacing my Trane but was talked into using a Brand X after it was hit by lightening. Never knew when Trane was running. This replacement sounds like sitting in front of Cessna air plane.
ken

From what I know on Trane units, this circuit on the 5 amp is meeting excess resistance from one of two spots. Either on the W2 wire (sometimes labeled as "aux" ) or the relay in the furnace is bad.
Be sure to match the fuse labeling on the schematic. A 10 amp fuse can indeed fix the problem but also can ice the air handlers transformer if a short remains.

 

[arrow]

Well, had to go back to the Dr this am, think my pneumonia is comming back.
.

it's not cold enough in fl to need heat now, and the ac works fine.. so it can set a few days easy..

Got the flu just before Christmas. 2 weeks later got pneumonia. 2 weeks later got pneumonia again. Dosage, type and time are critical for any antibiotics they give you. Still not perfect but I think I'm coming out of it.

 

[murphy1244]

Got the flu just before Christmas. 2 weeks later got pneumonia. 2 weeks later got pneumonia again. Dosage, type and time are critical for any antibiotics they give you. Still not perfect but I think I'm coming out of it.

When I had that dreaded flu around Christmas time my Lung doc put me on anti's just so I wouldn't come down with a case of pneumonia and it worked.