Honeywell Chronotherm III problem

For the last couple of days, the thermostat has been displaying on and off
something like
"737 -AC"
insted of the usual display of the current temp.

At the same time, it has NOT been heating up the house properly

I changed the batteries and tested the old ones. But they were fine.
So are the new ones

And yet, the heating system does not seem to be getting the house up to
comfortable temp

And I'm not sure if it's the furnace controls or what ?

I am presuming that this is some kind of error code
I have the user's manual, but it's pretty sparse about troubleshooting and
and totally empty about error codes.
And I'm not even sure if it's the furnace or the thermostat

Any help would be appreciated.

Dr. Hardcrab...

Most of the time if it says "AC" that means the thermostat is not getting
power. If the furnace is coming on, then I don't think that is the problem.
Make sure the metal "clips" that make contact with the batteries are clean.
If they are AND you put in new batteries, you may want to think about
getting a new thermostat...

Bubba...

7:37 is the Grennich mean chronological time displayed
-AC is a little more serious. This means your A/C will need to be
replaced immediately.
Bubba

One has to wonder the motivation of morons who respond with such nonsense to
what is a serious problem when the outside temperatures are around 0F
without the wind chill factor.

You give bubba's a bad name, guy

mm...

Yeah, he's like this a lot.,

I don't know your thermostat, or what is wrong, but as more and more
people have fancy therimostats, and it's cold out, maybe someone who
knows this stuff could give a backup procedure for bypassing the
thermostat entilrely on those nights and weekends when they find it
not working.

That is, all the thermostat does iirc is connect or not connect one
set of two wires (that turn the fan on as opposed to automatic) and
two of three wires (either the Heat and the Ground, or the AC and the
Ground) Nice people here have explained this already, and maybe if
one googled for "thermostat furnace red black green yellow**" one
could put together a set of rules for getting through the night.
(Well, I wouldn't let it run *all* night, but you could warm the place
up to 72, turn it off, and get up again when it was 62..

**or whatever the colors are

IIUC, there is no emergency need to have the fan be on anything but
automatic, so that just leaves 3 wires to fiddle with, and one is for
AC. Leaving just two wires. They can be jumpered at the thermostat
or at the furnace (without disconnecting the thermostat I think) Come
to think of it, you could probably take the thermostat out of any
space heater***, and use that in your jumper. Then you could get a
good night's sleep. OR you could install the thermostat you removed
from the wall when you put this one in. You saved it, I hope.

***Make sure you don't use one from a fan. They look the same but
work backwards.
Also I wonder about the -AC code being related to the batteries in the
thermostat, since batteries are DC. Car companies give out the codes;
it would be nice if thermostat companies did too.

Get a life

mm...

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