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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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All 3 of my thermostats are not working and AC is not on,

Customer Question

all 3 of my thermostats are not working and AC is not on
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: not sure- I find it bizarre that all 3 thermostats stopped working at the same time- they are all tied to one HVAC unit though
JA: Do you plan on doing the work yourself?
Customer: not sure- I wanted to try and rule out the obvious- I have checked ciircuit breaker we even replaced fuse in main return in attic
JA: Anything else we should know to help you best?
Customer: Unit is 10 years old-
Submitted: 2 months ago.
Category: HVAC
Expert:  BillyHvac replied 2 months ago.

Hello,

My name is Billy. Do you know where your zone panel is?

Customer: replied 2 months ago.
There are 3 boxes- The main breaker boxes in the garage there is a box in the attic and finally another outside attached to the HVAC unit
Customer: replied 2 months ago.
NO THANKS
Customer: replied 2 months ago.
I have tried all of the recommended things- flipping breaker- leaving HVAC off for 30 minutes and breaker flipped
Customer: replied 2 months ago.
I have replaced fuse in box up in attic
Customer: replied 2 months ago.
nothing
Expert:  BillyHvac replied 2 months ago.

What we need is the box that the thermostat wires go to..also from this box are zone damper wires...if you could post a pic it would help

Customer: replied 2 months ago.
Ok- where is this most likely located attic or outside?
Expert:  BillyHvac replied 2 months ago.

where is the blower unit? Attic?

Customer: replied 2 months ago.
lol. not sure
Expert:  BillyHvac replied 2 months ago.

where do you change your air filter at?

Customer: replied 2 months ago.
There is one in the hallway near the attic upstairs; one in the living area main floor; And one in the basement
Expert:  BillyHvac replied 2 months ago.

ok, we need to find the indoor blower unit..you have just one ac outside the home correct?

Customer: replied 2 months ago.
Correct
Expert:  BillyHvac replied 2 months ago.

great...now see if there is a brown thermostat wire that runs from the furnace to a square box mounted nearby

Customer: replied 2 months ago.
Will it not let me add a video
Expert:  BillyHvac replied 2 months ago.

video would have to be a link to a file share site. Pics will post here but videos need a link

Customer: replied 2 months ago.
Expert:  BillyHvac replied 2 months ago.

ok that box that says Honeywell is what powers your thermostats....are you willing to take front panel off?

Customer: replied 2 months ago.
Customer: replied 2 months ago.
Are there any precautions I should take
Expert:  BillyHvac replied 2 months ago.

takr front off and show pic of the board where I can see where wires attach..on that panel I believe power comes in the left side.

This entire box is only 24v....so there is absolutely no danger

Customer: replied 2 months ago.
Customer: replied 2 months ago.
One more
Customer: replied 2 months ago.
Are you still there Billy?
Expert:  BillyHvac replied 2 months ago.

ok just a moment...downloading

Expert:  BillyHvac replied 2 months ago.

see here

Customer: replied 2 months ago.
The big box
Expert:  BillyHvac replied 2 months ago.

do they go into the furnace or just mount on the silver box? I need to know where the wire ends actually mount/screw into

Customer: replied 2 months ago.
Hey look at this please
Expert:  BillyHvac replied 2 months ago.

great....now that transformer where the wires screw on...that is power for the zone control.

Now we need to see if that transformer has power...do you have a voltmeter?

Customer: replied 2 months ago.
Let me check in the garage please
Expert:  BillyHvac replied 2 months ago.

standing by

Customer: replied 2 months ago.
No
Expert:  BillyHvac replied 2 months ago.

Ok, can you tell me if the furnace appears to have power? Light lit on circuit board?

Customer: replied 2 months ago.
Let me check
Customer: replied 2 months ago.
Thought I saw yellow lights on the Honeywell device but then they went out
Customer: replied 2 months ago.
Want me to check the big unit correct
Expert:  BillyHvac replied 2 months ago.

correct

Customer: replied 2 months ago.
There is no noise or lights coming from it
Customer: replied 2 months ago.
There are two switches that are in the on position I flicked one in the off and back on
Expert:  BillyHvac replied 2 months ago.

can you show me pic of entire furnace

Customer: replied 2 months ago.
Expert:  BillyHvac replied 2 months ago.

see here

Expert:  BillyHvac replied 2 months ago.

and here

Customer: replied 2 months ago.
No no light. It's pitch black
Expert:  BillyHvac replied 2 months ago.

ok bear with me...

see here

Customer: replied 2 months ago.
Ox is covered and enclosed may have to use a wrench or something to get to it
Customer: replied 2 months ago.
Box
Expert:  BillyHvac replied 2 months ago.

at this point....the zone panel gets power from the transformer...the transformer gets power from furnace...the furnace has no power.

Back to the furnace power.....do not remove the box....was it a white box with switch labeled heat?

Customer: replied 2 months ago.
Sorry I'll need to check
Expert:  BillyHvac replied 2 months ago.

I saw a pic with a white switch under the zone panel labeled heat.

We need to see where power stops.....you already checked breaker box? breaker labeled furnace?

Customer: replied 2 months ago.
First two are of the area you highlighted second 2 are where I'm reference a switch
Customer: replied 2 months ago.
Oh are you referencing a light switch labeled heat ?
Expert:  BillyHvac replied 2 months ago.

yes...but also the main electrical panel with furnace breaker..not ac breaker.

Customer: replied 2 months ago.
OK that one is in the garage and I've already flipped it on and off as well as all the other circuit breaker's do you want me to take a picture of that
Customer: replied 2 months ago.
Hi Billy are you still there
Expert:  BillyHvac replied 2 months ago.

I am sorry lost connection...show me pic of electrical panel

Customer: replied 2 months ago.
Expert:  BillyHvac replied 2 months ago.

see here

Customer: replied 2 months ago.
Numerous times
Expert:  BillyHvac replied 2 months ago.

then the switch that says heat...must be removed and see if power is coming in there...and then out...that is pretty light duty switch for a furnace....but the next move is to check power with a meter at the switch