Results 1 to 2 of 2

Thread: Thermostat Digital Screen is Blank - Is it the AC Unit or the Furnace? How do I troubleshoot?

  1. #1
    Join Date
    Nov 2018
    Location
    Upland, CA
    Posts
    8

    Default Thermostat Digital Screen is Blank - Is it the AC Unit or the Furnace? How do I troubleshoot?

    Model Number: 80UHG Series
    Brand: -major brand-
    Age: More than 10 years

    80UHG Series

    The thermostat runs both the AC unit and the furnace. There is no reading on the digital screen. I used a voltmeter to determine that it is out because no voltage is going to the thermostat. I've researched a bit and found out it may be due to a blown fuse in one of the units. How do I know which one it is? The AC unit is a Tempstar model N4A348AKB300 (approx 5 years old) and the furnace is a Lennox 80UHG Series that's approx 15 years old.

  2. #2
    Join Date
    Jul 2006
    Location
    Murray, Utah 84107, United States
    Posts
    31,439

    Default

    Quote Originally Posted by LWelsh View Post
    I used a voltmeter to determine that it is out because no voltage is going to the thermostat.
    You'll need to look for the thermostat transformer. It's probably located on the control board for the furnace. Check for 120 VAC input and 24 VDC output. If the output voltage is correct at the transformer and not the thermostat there's a broken t-stat wire. If the output voltage is not correct you'll need to replace the board.
    OWNER RICK'S APPLIANCE REPAIR
    APPLIANCE TECHNICIAN FOR 31 YEARS
    REFRIGERATION SPECIALIST
    ONLINE SERV TECH: ApplianceBlog.com
    CERTIFIED TYPE 1; TYPE 2.....REFRIGERATION SERVICE E.S.

Similar Threads

  1. Replies: 0
    Last Post: November 19th, 2018, 03:15 PM
  2. GW397LXUS06 Whirlpool Gas Range LCD Screen Blank After Power Failure
    By josiahgarber in forum Whirlpool/Roper/Estate
    Replies: 5
    Last Post: November 16th, 2016, 12:29 AM
  3. Digital Control Panel Blank -
    By sharky300 in forum Frigidaire/Tappan/Electrolux
    Replies: 1
    Last Post: June 22nd, 2015, 09:21 PM
  4. digital display goes blank except for time
    By LornaJ in forum GE/Hotpoint
    Replies: 1
    Last Post: May 6th, 2013, 01:45 PM
  5. Blank Display Screen/some keys beep
    By Heather Noyer in forum Maytag/Magic Chef/Admiral/Jenn-Air
    Replies: 1
    Last Post: November 10th, 2011, 06:15 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
If you feel that you have benefited from this site, and would like to show your appreciation, you can throw a buck or two in the Appliance Blog Tip Jar - Thank you!