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My White-Rodgers thermostat just went blank. Nothing on the

display. Checked breakers inside and...
My White-Rodgers thermostat just went blank. Nothing on the display. Checked breakers inside and outside the house. No batteries in the thermostat. It's model # XXXXX
What might be causing this?
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Answered in 5 minutes by:
2/15/2012
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8,808
Experience: Furnace, A/C and heat pump specialist.
Verified

airheatman :

Hello. My name is XXXXX XXXXX do my best to answer your question.Remember, you are not charged and I am not paid until you accept my answer.

airheatman :

Did anything else lose power in house?

Customer:

No

Customer:

Everything else is fine

Customer:

Checked all breakers inside and outside as well

airheatman :

Do you have a multi meter to check voltage?

Full Size Image

Customer:

no

airheatman :

Can you do some hands on troubleshooting

Customer:

if it's not complicated...yes

airheatman :

What is the model on your indoor furnace or air handler?

Customer:

hold on and I'll get it

airheatman :

ok

Customer:

Got it

Customer:

Frigidaire 4 Ton Air Handler B3BV-048K-BB

airheatman :

OK

airheatman :

Now first, have you tried to reset the thermsat by pressing the reset button inside?

Customer:

no

Customer:

i didnt see a rest button

airheatman :

Ok lets start there

Customer:

*reset

Customer:

ok

airheatman :

Remove front cover

Customer:

done

airheatman :

Look just below the FAN switch

Customer:

ok

airheatman :

Do you see a button?

Customer:

hold on need to check the computers in the other room

airheatman :

OK

airheatman :

Should be a little button just below fan switch

Customer:

nope

Customer:

just the two slide switches

Customer:

fan and heat/cool/emer

Customer:

nothing below them

Customer:

just ABOVE them theres a little sliding switch

Customer:

black tab

airheatman :

See if you are able to open this file and tell me if this is your thermostat.

airheatman :

This is a small button, mayrequire using a straightened paperclip or simialr

Customer:

just found very tiny pushbutton switch under the fan switch

Customer:

was able to press it

airheatman :

OK

airheatman :

Did it reset?

Customer:

no

airheatman :

ok

Customer:

is there some special sequence?

airheatman :

Then we have probably lost power in the air handler somewhere.

Customer:

or does it need to be pressed and held?

airheatman :

It should just press onnce

airheatman :

Lets try one more thing before we go to air handler

Customer:

ok

airheatman :

Remove the R and G wire from thermostat and touch them together to see if fan comes on

Customer:

ok...jumped across the terminals and nothing

airheatman :

OK

airheatman :

We have lost power in air handelr

airheatman :

Can you open air handler?

Customer:

top or bottom part

Customer:

top yes

airheatman :

Top

Customer:

bottom questionable

Customer:

ok ill do it

Customer:

OK cover off

airheatman :

In the RED control wire from transformer to thermostat you should find a fuse like one of these two.If inline,you will have to open the plastic fuse holder to get to the fuse,We want to see if fuse is bllown.

Full Size Image
Full Size Image

Customer:

OK i see the plastic plug-type fuse on the circuit card to the left of the main power wires

Customer:

Is that it?

airheatman :

Should be .Check that fuse

Customer:

ok...i need to find some pliers to grab it...its awfully close to the hot wires

airheatman :

Turn power OFF while checking the fuse so you feel more safe

Customer:

got it out...fuse is good

airheatman :

OK

Customer:

sorobably transformer?

Customer:

so, probably

airheatman :

Next is going to be to check the fuses that supply power to the furnace down where power comes in

airheatman :

You need a meter to check them

Customer:

so bottom cover off?

airheatman :

WEhere does power come in? Do you see the high voltage coming into unit?

Customer:

yeah...i don't have one. i have an HVAC guy on the way, but at least he'll know where to start

airheatman :

You may have circuit breakers instead of fuses

Customer:

i can check

Customer:

hold on

Customer:

i can see where the 240 comes in but i cant get to it

Customer:

and there doesnt appear to be any fuses or breakers

airheatman :

Do you see any breakers on the unit iteself?

Customer:

no

Customer:

could they be in a box away from it?

airheatman :

How about a dsiconnect on wall right beside unit?

airheatman :

Maybe on wall right beside unit

Customer:

nope

Customer:

main power appears to come down from attic

airheatman :

Installer should have put a service disconnect by unit, but that is irrevellant to the problem

Customer:

could it be outside by the compressor?

airheatman :

THere will be one thr, but not controlling air handler

airheatman :

It should come from main panel

Customer:

checked all the main breakers

airheatman :

Somewhere we have lost power

Customer:

inside and outside

Customer:

the hvac people are saying the transformer

Customer:

sound right?

airheatman :

Either high voltage feeding transformer, the trasformer itself, or in low voltage between transformer and thermostat

Customer:

oh well itll be up to them now

Customer:

but thanks for all the good help

Customer:

im very satisfied

airheatman :

Has anything taken place such as construction or yard work around outdoor unit or anything where a wire could have gotten nicked or shorted

Customer:

no...and the unit was working a few hours ago

Customer:

there really arent any exposed wires outside

Customer:

and nothing the lawn guy couldve nicked

airheatman :

It is just highly unusual for transformer to blow unless there is a short, whci means, you need to have them find why (if it is blown)

Customer:

gotcha

Customer:

power surge maybe?

airheatman :

Like you say, from here. a meter is going to be necessary

Customer:

well, thanks a million for your help

airheatman :

A power surge can do it, but usually their are other signs

airheatman :

Thanks for allowing me to work with you

Customer:

my pleasure

Customer:

ill go click "Accept" now

airheatman :

Positive fedback appreciated and feel free to follow up and let me knowwhat they find.

Customer:

how do i reach you?

Customer:

e-mail?

airheatman :

The question is saved. Just sign in to JustAnswer and come back to question

Customer:

great...thanks again

airheatman :

If you ever need me at a later date,Just satrt your question with"Airheatman...." and I will be notified that you ahve requested me.

airheatman :

THank you

Customer:

great...will do. thanks

airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8,808
Experience: Furnace, A/C and heat pump specialist.
Verified
airheatman and 87 other HVAC Specialists are ready to help you
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airheatman
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8,808
8,808 Satisfied Customers
Experience: Furnace, A/C and heat pump specialist.

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