Honeywell TH9421C1004 VisionPRO IAQ Total Home Comfort System Logo

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Shawn Harksen Posted on Jan 15, 2013

How Do I Change battery in Honeywell TH9421C1004 Thermostat

Pulled off wall but didn't see battery, possibly behind front screen?

5 Related Answers

BarrettDenCo

Barrett Palumbo

  • 1772 Answers
  • Posted on Dec 19, 2010

SOURCE: The wall mounted thermostat in a condominium unit

i think you may have a fan/control board problem, if the thermostat turns on the fan, and you dont touch it, then the fan stops in a short time...
plus the fan is connected to a control board, like i said those thermostats hardly go bad...

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Anonymous

  • 557 Answers
  • Posted on Oct 23, 2010

SOURCE: my heat is ran by

yes it takes batteries

Anonymous

  • 767 Answers
  • Posted on Nov 08, 2010

SOURCE: I changed the batteries of

Hello my name is Heath it will be my pleasure to assist you. Take the new batteries out and let the display go completely blank then reinstall the new batteries and the lo batt light should go off.

Erik Dubose

  • 13 Answers
  • Posted on May 11, 2011

SOURCE: I have a honeywell ducted

it more than likely has a battery in it,,,, it can be hard wired and still run off batteries,,,,,,, double check it again,,,,,,,,,,,

Anonymous

  • 16 Answers
  • Posted on Jun 22, 2013

SOURCE: Blank Screen on thermostat

check your float switch. On your air hander you have 3/4 white pvc coming out of bottom of unit, where the water drains out. If you have a float and your drain line is plugged it will make your tstat go blank. vacuum the drain line where it comes out of the ground outside.

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Related Questions:

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How do you change the battery on Honeywell Th9421C1004 Thermo

Hello Bob Compher,

It looks like GETTING that battery is the biggest challenge...

After that it simply unplugs (like a portable phone battery).

Your manual is listed (below)

For assistance with this product please visit or call Honeywell Customer Care toll-free at
1-800-468-1502

Homepage

Honeywell VisionPRO IAQ Installation Manual Page 8
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Honeywell TH9421C1004 blank screen after power outage

We'd love to help resolve this. Please give us a call at 1.855.733.5465 and our customer support team will be happy to troubleshoot with you.
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1answer

TH9421C1004 touch screen stopped working

Make sure there is 24 Volts between the R & Common wires connected to the thermostat subbase.
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Touch screen stopped responding

Pull the thermostat face off the wall. Wait a few minutes, & gently line up the pins and place back on. Let display pull up. If that doesn't work, your thermostat is probably under warranty...Replace.
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1answer

Blank Screen on thermostat

check your float switch. On your air hander you have 3/4 white pvc coming out of bottom of unit, where the water drains out. If you have a float and your drain line is plugged it will make your tstat go blank. vacuum the drain line where it comes out of the ground outside.
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1answer
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2answers

Thermostat

That thermostat must be used with a THM5421C1008 Equipment Interface Module. The thermostat communicates with the module and the module is connected to the HVAC components.
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