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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8768
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Problems with thermostat TSTATCCNP01-8. 15 months ago a

Customer Question

Problems with thermostat TSTATCCNP01-8. 15 months ago a dehumidifier was installed. The AC was running and it kept cooling down way past where I had set the temp (74) to 55! (was away for a week). Switching off and back on fixed it. Later had issue with heat doing the same thing - heating up way past the temp set. Switching off and on fixed it. Now, the heat is coming on and again heating up way past the temp set. I turned on the AC and it got warmer! So I think the heat was running. Turned it all off and house cooled a little bit. Turned just the fan, and the heat came on and cycled on/off periodically. How can I fix this?
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


Please attach a well focused, close up photo of the wiring diagram glued inside the service panel,you can use the paper clip icon at the right end of the toolbar at the top of this dialog box,Include a picture of the thermostat wire connections to the printed circuit board in the same area.

If there is no paper clip icon, look for the '+attach files' link at left of your send button.

I can mark it up with trouble shooting instructions. You will need a multi meter ($30 at a hardware store) and some experience working with appliances, let me know a lot about your skill sets in those regards.

Customer: replied 1 year ago.
Customer: replied 1 year ago.
There you go.
Customer: replied 1 year ago.
Oh, skill sets ... i'm very technical but I do not have any experience with multi-meters or appliances. But this is something that can be fixed?
Expert:  Phil replied 1 year ago.

Hello again, thanks for the pictures. It looks like you have a heat pump...with back up heat, and that back up heat will be either a gas *furnace or an electric furnace/ air handler.

I need the wiring diagram glued inside the blower door of that furnace or air handler.

This can be fixed for sure, but it remains to be seen if it can be fixed by me working with you on line here or if you will need to hire a locally talented HVAC service outfit... a good percentage of those in that business are sufficiently talented... on average about 30%, I can help you locate and deal with that type of technician if it comes to that.

Right now I need photo's of wiring diagram glued to the blower service door inside (its a printed sheet of paper), and a photo of the printed circuit card in the same blower compartment... it is 6 x 8" in size approximately.

We can go from there.

Customer: replied 1 year ago.
okay, brb
Expert:  Phil replied 1 year ago.


Customer: replied 1 year ago.
Is this what you need?
Customer: replied 1 year ago.
Ah, the printed circuit card. Here's the thing ... i couldn't figure out which one was the blower door but I did find these wiring diagrams on the outside of the unit. I unscrewed the screws that held this panel in place but there was nothing of note behind it. There was a thermal insulation pad on the inside of the door, that was all.
Customer: replied 1 year ago.
I have the user manual for the Air Handler. The wiring diagram is in here. However, as you say, we need to see the actual circuit board to check that it is wired correctly.
Customer: replied 1 year ago.
Okay, so i'm thinking that the blower compartment was the door that I took off. I will look at it again and take a picture of it for you.
Expert:  Phil replied 1 year ago.


You should see the thermostat wire bundle going into the electric furnace, do what it takes to follow that wire... to where it lands in the furnace... there will be a wiring diagram there and you will be able to see how and where the thermostat wires terminate.

I need those photos....

Note your last wiring diagram photo was reasonably well focused the two previous were not well focused enough to read... pay close attention to the focus.

Customer: replied 1 year ago.
Think i found it.
Customer: replied 1 year ago.
Expert:  Phil replied 1 year ago.

we are getting closer, but I do not see where there the thermostat wires connect anywhere... those are small 18 gage wires coming in a bundle from the thermostat.

And i do not see a wiring diagram, there is one in the same area 99% of the time.

Customer: replied 1 year ago.
okay, let me look again. So the .pdf did not help? nor the photo of the wiring diagram on the outside of the air handler?
Customer: replied 1 year ago.
heading back down to the basement ...
Customer: replied 1 year ago.
okay, i found it. I need to get a lamp and something to stand on.
Expert:  Phil replied 1 year ago.

Thanks, this more or less tells two things, getting this furnace wired correctly was a problem from the start because of poor access, and repairing it is not going to work by remote control. It is going to take one of more diligent and knowledgeable HVAC technicians to sort this out for you.

If you can tell me which direction you are from the center of the nearest city I will look for the most likely possibilities of getting that sort of technician to come out.

Customer: replied 1 year ago.
thanks. I'm in Alexandria, VA which is just across the Potomac from Washington, DC ... to the southwest. 22314. I need to go now. Can you send your suggestions to my email? I feel it was worth the $28 just to narrow things down and to get a proper technician out here. Thank you.
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** your consideration.

I do not have your email, to do that it is an additional charge by the web site that enables them to keep up the quality control, which is not warranted in this case.

I will post what I have for you here, let me know if that is OK with you.

This is oldest and best rated in the area, over 100 years in business now, they must be

doing something right.

This company has been in the area for 20 years with a 4.4 out of 5 rating on 35 reports.

Take your pick, ask each for a service call to diagnose the problem and provide a firm quote to fix the problem.

Thanks for letting me work with you. When we are finished, if my answer has been polite, professional,and thorough, please click one of the ratings . If you still need help let me know!. Expert is not paid for assisting you until you rate answer. Feel free to follow up for30 days at no additional cost.