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HVAC Guru
HVAC Guru, HVAC TECH
Category: HVAC
Satisfied Customers: 13988
Experience:  15yrs in the HVAC industry with certificates and degrees.
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MY THERMOSTAT GOES DEAD EVERY TWO WEEKS, EVERYTHING LOOKS

Customer Question

MY THERMOSTAT GOES DEAD EVERY TWO WEEKS, EVERYTHING LOOKS WIRED CORRECTLY BUT SINCE I NEED TO KEEP REPLACING THE BATTERIES IM SURE THERE IS NO POWER GOING TO THE THERMOSTAT.
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: IM SURE IT IS JUST THE WIRING, BEFORE ADDING THE PRSTIGE UNIT THERE WAS NOT A PROBLEM
JA: Do you plan on doing the work yourself?
Customer: THIS PART
JA: Anything else we should know to help you best?
Customer: ANYTHING YOU WANT, EVERYTHING ELSE WORKS FINE
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and then connect you two.
Submitted: 5 months ago.
Category: HVAC
Expert:  HVAC Guru replied 5 months ago.

Hello and thanks for using this service, if you have been waiting do not worry or get upset. I am HVAC Guru an extremely experienced tech on the site and I try to get to as many customers as I can. I just picked up your question now. NOTE it takes time for me to type research and add links so please wait for me to respond back I can only do this so fast. Secondly I am not paid anything until you rate my service good using the STAR RATING LINK at the top of your page, the money is paid to the site not me directly.

It is a battery thermostat not wired to a C wire correct?

Customer: replied 5 months ago.
PRESTIGE THX9321 WITH EIM MODULE. BATTERY IS FOR BACK UP ONLY BUT SEEMS TO BE WORKING ONLY ON THE BATTERY A SIMPLE 2032 WATCH TYPE BATTERY. I CAN SEND PICTURES. BLUE WIRES ARE WIRED TO C AND RED TO R WITH JUMPERS, IN THE HOUSE THE UNIT IS WIRED WITH WHITE WIRE TO C AND RED WIRE TO R. BLUE AND GREEN WIRES WHICH WERE BEING USED WITH OLD SYSTEM ARE NOT CONNECTED. TESTED WHITE AND RED AND THEY ARE POWERED.
Expert:  HVAC Guru replied 5 months ago.

You need to check between the RED and the C connection for 24 volts AC, if you do not have that then you have lost the C wire. You may have a wiring issue to the thermostat or possibly a blown fuse in the furnace or airhandler killing power to the thermostat. If you do have power across those two connections there is something wrong with the thermostat and it would need to be changed.

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am paid anything through the site and that will also get you a DIRECT LINK emailed to you to get back to me!.....tips are greatly appreciated so thank you very much for using this service. If you have any other questions just post back to me here anytime!

Customer: replied 5 months ago.
EIM MODEL IS THM5421R. WE ARE USING A LENNOX GAS FURNACE SINGLE STAGE HEAT. THE AC UNIT IS A TRANE WITH DUAL STAGE BUT IBELIEVE BECAUSE OF THE OLDER FURNACE WE ARE ALSO ON SINGLE STAGE.
Customer: replied 5 months ago.
C AND R TESTED POSITIVE WITH 24 VOLTS
Expert:  HVAC Guru replied 5 months ago.

Yes then the thermostat should never go dead, I would say it is time for a new thermostat as there is no reason it should go dead.

Customer: replied 5 months ago.
ITS NEW AND WORKED PERFECTLY BEFORE WE ADDED AC UNIT.