Heat Pump/Air Handler went out completely

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Before I decide who to call on my problem I'd like to get some sort of idea what the problem is...
One morning while in Heat mode my Heat Pump simply stopped running all together, not even a temp readout was on the digital thermostat. Just nothing. I could not get the Air Handler fan to blow by setting it to do so at the thermostat.
There is an 10 year old air handler in the attic and a 9 month old heat pump outside.
No circuit breakers were tripped. I am able to get to the attic air handler and can see that its two breakers were not tripped either.
I checked out at the heat pump and there seems to be power going to the unit, (verified by a non-contact voltage probe) yet the small green "Power" light inside the Tempstar unit isn't lighting up.
There are 2 breakers serving the Air Handler, I suppose one is for the backup heat strips, the other for the fan motor. There is one breaker serving the Heat Pump outside. All these circuits seem to be ok as they leave the Main circuit box. They never tripped at the time of the event.
That is about all I can decipher at this time as I really don't want to open the sides of the Trane Air Handler to check the wiring inside.
I am just stumped at what it could be, especially as the Honeywell thermostat simply reads blank (its a 24 volt, no battery). I tried using a small lamp tester across all the contacts inside the thermostat contacts but non of them seem to be 'hot'.
The heat pump is a new replacement, 8 months old. The Air Handler is about 10 years old.
Any ideas about what could have gone so wrong, so quickly?
What seems strange is the blank Thermostat and the Blank Heat Pump. The 'who to call dilemma' is between the Installer of the new Heat Pump and the company who installed the Air Handler (no warranty left) as I've learned that you may as well just call the company you expect to install any replacement unit first because otherwise you will just be wasting a 100$ service call which won't be applied to the price of any new equipment installed.
I just am looking for some sort of clue as to what might be wrong before I call them. The house has an older heat system (elec baseboard) so there is no huge rush.
Thanks
Phil
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snipped-for-privacy@gmail.com wrote:

Phil;
If the installation is less than 8 mos. old, it should still be under the installation warranty. Call the installing contractor out and have him correct the failure. This shouldn't cost you a dime. You already paid for a quality installatiion, and obviously there's a problem.
--
Zyp



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snipped-for-privacy@gmail.com wrote:

It could be the transformer in the furnace.
just be careful that you do not hurt yourself if you try to repair.
If you think it is under warranty then call out the ones who installed it or last worked on it.
--
Moe Jones
HVAC Service Technician
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Moe Jones wrote:

Moe;
Didn't he say *"Heat Pump"* and that there was an *"Air Handler"* in the attic? Not a furnace?
And, couldn't the outdoor unit that was installed during the summer, have been "mis-wired" by the installing conrtactor causing a low voltage failure in the air handler?
Phil;
Call out the original installing contractor.
--
Zyp



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Zyp wrote:

Furnace or Air Handler they both put out heat. Generally I associate Air Handler with cooling only with some sort of a duct heater.

Yes, but most likely when a good installer replaces a heat-pump he will check the new equipment in both modes (Cooling & Heating) to make sure all is good.

--
Moe Jones
HVAC Service Technician
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Just wondering. If it was mis-wired for heating (it has cooled fine for months) what might have triggered a failure after about 3 weeks of heating use? Could part of its various stages not have been triggered to run until it had to operate at a colder temp outside? Its not even gotten below freezing outside here, and I believe it was in the 40's the morning it all stopped working.
phil
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Well, the case for the air handler appears to be sealed with goo, so I didn't open it up to look around inside. Too bad. I at least wanted to look inside to see what was what in there. Phil
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Well, the case for the air handler appears to be sealed with goo, so I didn't open it up to look around inside. Too bad. I at least wanted to look inside to see what was what in there. Phil
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Well, the case for the air handler appears to be sealed with goo, so I didn't open it up to look around inside. Too bad. I at least wanted to look inside to see what was what in there. Phil
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On Nov 5, 2:18 pm, snipped-for-privacy@gmail.com wrote:

As far as I know (caveat : I'm a software engineer, not an AC repair guy, although I did fix my own heat pump a few years ago when the relay that controls the reversing coil got sticky), the 24 volts that powers the thermostat originates at a transformer in the unit. If there is power to the transformer inside the unit, and no 24 volts at the thermostat, then you've either got a bad transformer or an open connection somewhere.
Without that 24 volts, you're not going to switch the main contactor that turns everything else on.
Jerry
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Thanks for the input.
I reluctantly called the installer of the Heat Pump and he agreed to come out but wants 84$ to check out the entire system because he didn't install any of the interior parts of the system. All he installed was a replacement Heat Pump 8 months ago and that is all thats covered in parts and labor. He strongly suspects that the problem lies in the Air Handler.
That is why I was trying to figure out what was broken. If its the Air Handler in the attic, its ten years old and theres no warranty at all with anyone anymore, so anyone could work on it.
I am currently suspecting that the problem might lie with the thermostat's transformer. But I cannot find it. I am having a hard time tracing the actual power line to the thermostat as I wanted to check the transformer too. I guess my next step is to keep trying to trace back to find the transformer...but I'm not sure where it could be and was thinking it possibly was inside the Air Handler case, which I really don't want to open unless I know what I'm looking for.
phil
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I found the papers for the air handler and the transformer is inside the unit, which I'm sure you guys already knew.
There was also a 'Functional Parts List' which includes things like Coil and Drain Pans, Capacitor, Filter, 5 amp fuse, Motor/indoor, Relay/Time delay, Restrictor, tube assembly, Wheel/blower, and TRANSFORMER. Which I thought was encouraging, hoping that it still might just be a bad transformer which could possibly be replaced.
Transformer, 40 VA, 200/230V PRI, 24V,SEC...... Trane Part number TRR01441
The unit is a Trane Model TWG036A140B0
Anyone know if this would be a fixable item, or how likely it would possibly be to go bad after 10 years?
Thanks
phil
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I found the papers for the air handler and the transformer is inside the unit, which I'm sure you guys already knew.
There was also a 'Functional Parts List' which includes things like Coil and Drain Pans, Capacitor, Filter, 5 amp fuse, Motor/indoor, Relay/Time delay, Restrictor, tube assembly, Wheel/blower, and TRANSFORMER. Which I thought was encouraging, hoping that it still might just be a bad transformer which could possibly be replaced.
Transformer, 40 VA, 200/230V PRI, 24V,SEC...... Trane Part number TRR01441
The unit is a Trane Model TWG036A140B0
Anyone know if this would be a fixable item, or how likely it would possibly be to go bad after 10 years?
Thanks
phil
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Jerry wrote:

Jerry;
All that's probably true, but without a meter to read, it's all a guess. No?
Phil;
Call out the original installing contractor.
--
Zyp



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<Follow your thermostat wires and they will probably go into the air handler, if your have power to the air handler, then you will probably have to open it up. The themostat wires go into a circuit or panel to pick up the 24v, and there might be a fuse in there that popped, or you might see the bad transformer in there. You might even have a thermal ckt breaker trip on youre blower motor, which might have tripped from overload due to a clogged filter.
Just my 2 cents! >
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In reading the schematic it does show a 5 amp (auto type) fuse, which I also would definitely think might be bad too, no idea why it would have gone bad though.
phil
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snipped-for-privacy@gmail.com wrote:

Phil;
Control transformers do not go out on their own. Somthing must short out the connection and cause a failure. Check the 5 amp fuse. If it is blown, you've got somthing that may be shorted. There is a line running to your new outdoor unit that should have from 5 to 7 wires in the cable. If the installer mis-wired the control board, he could have smoked the transformer on the call for heat. Or, he could have mis-wired the defrost cycle wiring. When the outdoor unit called for defrost, it signals the indoor unit to energize the auxilary heat. So you should mention to your installing contractor that maybe there's a problem and that he shouldn't charge you until it's decided what the actuall failure is.
--
Zyp



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The system had been in heat mode for probably 3 weeks, but it was somewhat colder the night/morning it went out..not a tremendous amount colder though.
...for whatever thats worth.
phil
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Zyp,
As it now stands, the installer of the new heat pump is coming out to look at it. I went with him because that's the only source i would have for any warranty work if the new heat pump had gone bad (or possibly had been miswired). But if had been miss-wired wouldn't the problem have occurred within the 3 weeks its been running periodically for heat?
phil
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On Nov 5, 10:50 pm, snipped-for-privacy@gmail.com wrote:

Is it possible that when it stopped working you went to "emergency heat" which would be likely an electric resistive element in the transformer? That would be one explanation as to why it worked fine on regular heat for a couple weeks and then suddenly failed. Did it get significantly colder in your area immediately prior to the failure? That would explain what you describe, and also point to something shorted that would only show up when the thermostat called for the auxiliary electric heat to kick in.
nate
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