[techiej]

Lately we've been having a problem where the system is running the fan by itself. This is an American Standard Series 80 One-Stage with a Honeywell Chromotherm IV thermostat.

Right now the system is set for AC and the fan to AUTO. Most of the time everything is fine. But every couple of days (sometimes weeks) we would notice that the fan is running but not the compressor. In checking the thermostat it shows the fan as ON instead of AUTO. If we switch it to AUTO the fan stops and all is fine for a while (days or weeks).

Any clues or ideas?

 

[medic2258]

@w30olds

 

[M&P15T]

Thermostat battery? Someone in the home messing with it?

Since the thermostat is magically setting itself to "FAN ON", I'm think it's the thermostat itself.

 

[techiej]

No one else messing with it - unless the dog has figured out how to reach and change it, it's just the wife and I. Also, in order to switch it you need to open the flip down cover so it's not going to change by being bumped by accident.

Didn't know that there was a battery - will need to pop the cover and take a look.

 

[Dave514]

I'm gonna guess thermostat(I'd switch the battery first) or blower control board but that's odd that it switches to ON.

 

[SinCityGlocker]

Some Honeywell thermostats have a "Circulation" mode that can be activated in the advanced settings. This will run the indoor fan a certain percentage of the non-cooling time to keep temperatures more even throughout the home. On the focus pro and vision pro stats this is a user setting on the main screen. If the thermostat has been in use and this just now came up, I would change the thermostat. If someone has been in the advanced settings lately and played with the Circulation setting or accidentally changed the application from residential to commercial you could reprogram.

 

[techiej]

Well - I popped the cover and checked - it is not a battery model.

I'll probably wait until it fails more regularly and then replace it.

Thanks for your help!

 

[w30olds]

I'm guessing something in the programming is causing the fan to come on. Could be setup for circulating. Anyway to go into your programming and check the fan settings? That's all I got at the moment.

Sent from my SM-G900V using Tapatalk

 

[Hauptmann6]

I've seen that stat go wonky quite a bit. When it does it more, toss it and put in a different stat. That is NOT one of honeywells better stats.

 

[bgirls]

I would think it has to have a battery, something to retain the settings in memory

 

[volky]

poltergeist.

 

[ChuteTheMall]

Your electric bill might pick up a few extra digits if you postpone repairs. :alex:

 

[R*E]

You need a new flux capacitor.

 

[ked]

 

[OttoLoader]

I had a similar problem.
The fan ran but compressor did not run.
Changed thermostat batteries.
About a week later the capacitor started to buzz.
Put in new capacitor and all is well.
The capacitor was a few years old.

 

[LEO/Dad]

Time for a Wi-Fi stat. Many of us retirement folks use these to check on our homeplace when we take our winter trips south. Very useful. Sometimes they need a little tweaking. Friends a/c came on when furnace started. Had to call Honeywell. Tech said stat thought they had h/p. Corrected. Read some of the reviews.

https://www.homedepot.com/p/Honeywe...mable-Thermostat-Free-App-RTH6580WF/203556922