Armed Polite Society
Main Forums => The Roundtable => Topic started by: Regolith on September 15, 2017, 11:10:41 PM
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We've got a Honeywell TH9421C1004 VisionPro IAQ thermostat that currently has a blank screen and a constantly blinking red LED in the upper right corner of the faceplate. I can't find anything ANYWHERE that states definitely what that light means. There's nothing about it in the thermostat's manual at all, and nothing about it in the heat pump's manual either.
Yesterday we had a long power outage, and after the power came on the screen was much dimmer than usual, and then sometime this afternoon it went away completely and the red light started blinking. It's a wired unit, and I can't find any batteries except what appears to be a coin battery in near-inaccessible location (I could probably get to it if I had to, but it appears they didn't want it to be user-serviceable).
Any of you HVAC guys have any idea what's going on? The heat pump is a Trane 4TWR5, if that helps.
This is kind of what it looks like (I edited it with gimp because I didn't want to get the tripod out to catch the blinking light):
(https://i.imgur.com/TndqPm1.jpg)
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Try unplugging the house and then plugging it back in again.
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Honeywell, Rockwell...
Close enough
https://www.youtube.com/watch?v=RXJKdh1KZ0w (https://www.youtube.com/watch?v=RXJKdh1KZ0w)
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Honeywell, Rockwell...
Close enough
https://www.youtube.com/watch?v=RXJKdh1KZ0w (https://www.youtube.com/watch?v=RXJKdh1KZ0w)
James Doohan was soooooooooo much better at that... [tinfoil] :laugh: ;/..
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Probably an emergency heat indicator.
From a (different :lol: ) Honeywell manual:
Heat Pump Emergency Heat LED Indication
(Requires 24 Vac Common Connection)
The thermostat uses a red LED indicator that lights when the thermostat is in the Emergency Heat mode. The LED is located in the upper right corner of the thermostat. It is visible only when on. When the thermost at is in the Em. Heat system mode, the L terminal is continuously energized and the LED is on.
Are you in emergency heat mode?
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Are you in emergency heat mode?
Nope. Though it's a bit hard to tell because the screen is off.
It was in cool mode prior to the screen blanking. If I pull it off the wall and put it back on, everything comes back up the way it as for a few minutes (still in cool mode), then the screen blanks and the light starts flashing.
The heat pump itself isn't doing anything.
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Try replacing that coin battery. It may be the backup power source, and if you had a prolonged power outage it may have gotten run down.
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I guess you may have already seen this one in your searches.
https://www.youtube.com/watch?v=KcC9CpGblqU
bob
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Try replacing that coin battery. It may be the backup power source, and if you had a prolonged power outage it may have gotten run down.
I was thinking it could be something like that. Think I'll give this a try. Have to go into town tomorrow to get the battery, though.
I guess you may have already seen this one in your searches.
https://www.youtube.com/watch?v=KcC9CpGblqU
bob
Unfortunately, that's not exactly same model. Mine uses a coin battery instead of AAAs, and you have to pull the front faceplate of the unit off, remove the touch screen and circuit board from the housing, and THEN you can get to the coin battery, which is mounted on the back of the circuit board.
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Have you checked all your breakers and made sure none of them are tripped?
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I just found this...
http://www.hannabery.com/faq9.shtml
According to that, your outdoor unit might be in lockout mode.
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Have you checked all your breakers and made sure none of them are tripped?
Related to that, do you have a remote thermometer that you can shoot up to one of your registers and get a temp reading? If so, does it seem warmer than normal (I'm assuming you're using AC this time of year)?
While I don't have a thermostat like yours, after power outages (or even brownouts) at both my house and my rentals, I have had the following happen several times: Unit turns on, but air comes out of the registers at around 70+ degrees instead of the high 50s.
My HVAC guy taught me a trick, because he runs into a lot of this. I forget which component he said is affected, but often after an outage something goes out of whack if the unit was running when the outage hit. The way he told me to fix it is to turn off the thermostat, shut off power at the breaker for 30 seconds than turn the breaker on again and turn on the thermostat. This has worked every time for me.
Kinda like "Have you tried turning it off and on again?" :laugh:
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The little transformer that makes the 24 volts. Can you check that?
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Have you checked all your breakers and made sure none of them are tripped?
Yes. One was tripped right after the power outage, but it wasn't related to the heat pump or thermostat.
I just found this...
http://www.hannabery.com/faq9.shtml
According to that, your outdoor unit might be in lockout mode.
Related to that, do you have a remote thermometer that you can shoot up to one of your registers and get a temp reading? If so, does it seem warmer than normal (I'm assuming you're using AC this time of year)?
While I don't have a thermostat like yours, after power outages (or even brownouts) at both my house and my rentals, I have had the following happen several times: Unit turns on, but air comes out of the registers at around 70+ degrees instead of the high 50s.
My HVAC guy taught me a trick, because he runs into a lot of this. I forget which component he said is affected, but often after an outage something goes out of whack if the unit was running when the outage hit. The way he told me to fix it is to turn off the thermostat, shut off power at the breaker for 30 seconds than turn the breaker on again and turn on the thermostat. This has worked every time for me.
Kinda like "Have you tried turning it off and on again?" :laugh:
The nothing's running, so there's nothing to check. But I think I'll try turning everything off and on again, per Mike's link.
The little transformer that makes the 24 volts. Can you check that?
I'm not sure what you're talking about, but if you can clarify I probably can.
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Just turned everything off and then on again. No joy. =(
Gonna try the battery next, I guess, soon as I have time to get to the store.
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Are you sure you aren't missing 3 AA batteries ??
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Are you sure you aren't missing 3 AA batteries ??
No place to put them. :P
I replaced the coin battery about 10 minutes ago, and now everything is working, so it looks like that may have been the issue.
Thanks for the help. =)