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HVAC Guru
HVAC Guru, HVAC TECH
Category: HVAC
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Experience:  15yrs in the HVAC industry with certificates and degrees.
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Lennox digital theromstat is blank and the air is not on :

Customer Question

Lennox digital theromstat is blank and the air is not on
JA: Sometimes HVAC issues that that you think will be really complicated end up being easy to fix. The HVAC Technician I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so we can help you best.
Customer: Lennox digital thermostat is black and the ac is off.
JA: Is there anything else important you think the HVAC Technician should know?
Customer: The other unit upstairs is on and working 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: 1 year ago.
Category: HVAC
Expert:  Gaztech replied 1 year ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue.

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Expert:  HVAC Guru replied 1 year 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.

Answer:

The most common cause is a blow low voltage fuse on the control board in the furnace or airhandler, that supplies power to the thermostat. There should be a slot style fuse or inline fuse on the board in the unit, check for that and see.

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.....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!

Expert:  Gaztech replied 1 year ago.

The most common cause is a blow low voltage fuse on the control board in the furnace or airhandler, that supplies power to the thermostat. There should be a slot style fuse or inline fuse on the board in the unit, check for that and see.

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.....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!

Expert:  HVAC Guru replied 1 year ago.

Sir I am sorry Gaztech has just copied my answer and posted it, if you need anything let me know

HVAC GURU

Customer: replied 1 year ago.
I am in the box but do not see a fuse
Expert:  HVAC Guru replied 1 year ago.

Ok do you see the control board? You should be looking for this...

CLICKHERE

HVAC GURU

Customer: replied 1 year ago.
I see the control board
Expert:  HVAC Guru replied 1 year ago.

OK do you see a slot fuse on it?

Customer: replied 1 year ago.
No
Expert:  HVAC Guru replied 1 year ago.

OK do you see any inline bus fuse going to the board at all or on the board? Like a cylinder style fuse

Customer: replied 1 year ago.
Found the box fuse. It is purple and has an E on it. It does not appear to be broken.
Expert:  HVAC Guru replied 1 year ago.

Yes that is the fuse double check it with a meter and see

Customer: replied 1 year ago.
I see power on the board
Expert:  HVAC Guru replied 1 year ago.

Are the lights flashing an error?

Customer: replied 1 year ago.
The go E. 5. 4. 2. 1
Customer: replied 1 year ago.
Ready
the lights are flashing E 5 4 3 2 1
Customer: replied 1 year ago.
Expert:  HVAC Guru replied 1 year ago.

Do you see the error code list on the panel that you took off it should be listed there what is the error?

Customer: replied 1 year ago.
E. 5. 4. 3. 2. 1
Expert:  HVAC Guru replied 1 year ago.

Is there an error list taped to the panel or what exact mode is it?

Customer: replied 1 year ago.
Don't see one
Expert:  HVAC Guru replied 1 year ago.

What is the complete model of the unit, it is getting late we may have to pick this up tomorrow.

Customer: replied 1 year ago.
Lennox m/n cbx32mv-036Sn5811j07737
Customer: replied 1 year ago.
E105
Expert:  HVAC Guru replied 1 year ago.

That is a communication failure between the unit and the thermostat, you may have a bad control board. Try to power everything down for a minute and power it all back on. See if it will work then if not you likely have a failed control board.

All I ask is please use the star rating link before leaving tonight thanks

Customer: replied 1 year ago.
Power down outside?
Expert:  HVAC Guru replied 1 year ago.

Yes power the entire system down at the breaker panel