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I had to change batteries on my thermostat abd now it's not…

Customer Question
I had to change...

I had to change batteries on my thermostat abd now it's not working. It says 75 U4

Contractor's Assistant: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?

Just thermostat

Contractor's Assistant: Do you plan on doing the work yourself?

It's am apartment. I called the office but got voicemail

Contractor's Assistant: Anything else we should know to help you best?

It's a White Rodgers model #1F78 NON -PRGM

Submitted: 11 months ago.Category: HVAC
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HVAC Technician: airheatman, HVAC Technician replied 11 months ago

Should say U4 is not normal error

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Customer reply replied 11 months ago
I already did that reset. Saw it online. Just tried it again. Now says 72 what looks like an L with an extra piece going up right side bit not quite making the U shape again and the number 2
HVAC Technician: airheatman, HVAC Technician replied 11 months ago

If you remove thermostat from subbase does it stay same?

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Customer reply replied 11 months ago
It's now changed to 75 U5
HVAC Technician: airheatman, HVAC Technician replied 11 months ago

Doublecheck batteries and make sure polarity is correct

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HVAC Technician: airheatman, HVAC Technician replied 11 months ago

What numbers follow the 1F78? I will grab a manual

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Customer reply replied 11 months ago
There's no other numbers
Customer reply replied 11 months ago
Now the display is gone
HVAC Technician: airheatman, HVAC Technician replied 11 months ago

Should be some numbers like 152 or 144 as there are a few models of the 1F78.

There is one trick I have seen work to reset these digital thermostats that works sometimes. That is to remove batteries and install them backwards for 5 seconds, Then remove and install properly,If this does not reset the little computer board in the thermostat you will need to replace the thermostat.

Note: Occasionally , this will not work and will even cause thermostat to start smoking.If so simply remove batteries.If thermostat is not working already, it is worthless anyway, so no harm done .I have seen it work about 20 per cent of the time. So if that is something you are comfortable doing would try it.Could save you having to buy another thermostat.Otherwise, just go ahead and replace it.

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Customer reply replied 11 months ago
It's not working. Thanks anyway. I'll have to call someone out.
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