Question about Heating & Cooling

1 Answer

Chronotherm III not working: I set the temp to 70 degree hold, it's 65 now. The system clicks on, displays ''heat on'' but nothing coming out of vents. I switch to off to reset, wait 10 seconds, switch to heat, then adjust to hold at 67 degrees and it will kick on for about 5 minutes then cuts off, to never cut back on again until i reset it again. Any ideas? The instructions manual says contact your HVAC contractor, obvisouly trying to avoid that.

Posted by on

  • 4 more comments 
  • abfergus Dec 15, 2009

    Yes, the furnance is on. Heat is actually produced after "reseting" (clicking to Off/AC then back to heat) but typically only runs through one cycle.

  • abfergus Jan 28, 2010

    No haven't got the solution yet. It's not the thermostat b/c I replaced the thermostat and heat still not staying on. I had HVAC repairman come and he had problems figuring out what was wrong. After over an hour he determined it must be a bad circuit board, and would be $2k to replace. Then he suggested I replace the whole unit for, gulp, $7k.

    That was 3 weeks ago, and am skeptical of the diagnosis. I have done more research and now convinced it is either the thermocouple or in fact the circuit board. I was going to stop by Lowes tonight and see if they had a replacement thermocouple for my Trane Unit (might as well try the cheap alternative...)

    Other things I noticed, the fan will come on no problem, but the heat will come on for one cycle only.

    It's suppose to get down to 8 degrees this weekend so I need a fix.

  • abfergus Feb 01, 2010

    Never messed with thermocouple. Went to Lowes and the assistant told me it wouldn't be the thermocouple if the pilot light is igniting, also they didn't even sell thermocouples......

    Well turns out my furnace now starting work again, at least for now. My furnace seems to work really well when it's below freezing out. Other then that it only runs one cycle. I have a packaged unit - Trane YCC024 that was installed in 1996.

    My temp. solution has been to get 3 electric heaters that are running when it's 40-50 degrees and pray the furnace cuts on when the temperature drops below freezing...

  • Robotinner May 11, 2010

    I just got confirmation back on this via Email. Took a while thank god your not a popscicle by now. Just for grins jump the R and W terminal at the thermostat and see how long it runs. if it is cutting out when these are jumped you may be tripping the high limit on the furnace. Just odd that the unit runs better when its cold. Take temperatures on incoming air little before filter(may need a probe thermometer) and supply air temp about a foot away from plenum then document the difference between them. As far as the price on this equipment seems a little out there, is this including a AC unit too? I am trying to help but need more info to make a proper diagnosis Sunsetmech

  • Robotinner May 11, 2010

    is the furnace turning on(flames?)

  • Chandler Ede
    Chandler Ede May 11, 2010

    Can you give us an idea what make and model your heating system is?



1 Answer

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

Hi Abfergus,
I am having the exact same problems. Were you able to figure out what was wrong?
Thanks for any isight you may have.

Posted on Jan 28, 2010

  • coldinidaho Feb 01, 2010

    Hi Abfegus,

    Wondering if the thermocouple was the solution. Tinkered around with mine over the weekend, with no solution in sight. I think that I'm going to have to break down and call in a professional. Just wanting to know if you had any luck over the weekend. Thanks for the help.




1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

Is it normal for a chronotherm iv plus to have the highest cool setting to be 85 and the highest heat setting to be 65? I feel like its reversed.

Those may be the upper and lower limits. For cooling you would not want the system to allow the temp to rise above 85. Conversely when heating you would not want the heating system to go below 65.

Jan 23, 2015 | Heating & Cooling

1 Answer


the thermostats work from the room temperature and not outside temp
could be a problem with the thermostats or the setting procedure

Oct 29, 2017 | Samsung Heating & Cooling

1 Answer

Furnance will not start until room temp is at least 5 degrees below set temp ie temp set at 70 , wont start till it reaches 66 or 65 degrees

themostat is bad, or the heat anticipator on the stat is bad, which means you still need a new stat

Oct 23, 2010 | Heating & Cooling

1 Answer

Chronotherm III displays 32 deg for room temp, which is really around 70 deg. No action called for by the instrument. Batteries had died and replaced. My first guess was the actual temp sensor was...

Go to
Under red welcome sign
Bottom red highlighted box literature/image search
Type in thermostat model number
Click on arrow to right
Then click on the PDF files owners manual / installation instructions
If you can’t find what you want, the bottom left and bottom of web
Page, they have homeowners assistance and Home products to get the help you need.

Apr 28, 2010 | Honeywell Electronic Programmable...

1 Answer

Chronotherm Three thermostat vs Buderus Logamatic Computer.

The outdoor thermostat senses the the temp of the outside air, and adjust the boiler water temp according to what it knows is best. The reason that the boiler is running longer is the old boiler used to be constantly sending 180ish degree water to the baseboard, now that water may only be 140ish degrees. The idea behind this is to reduce off cycle heat loss, as the greater the temp difference between the air temp and water temp, the quicker you loss heat. The theory in boiler run time is this, the less times it starts and stops, and the long run times will give you the best efficiency. Hope this answers you questions.

Sep 28, 2009 | Honeywell Power Humidifier: Furnace...

1 Answer

Cannot set heat setting by using "hold" feature

make sure it is not telling you room temp, some of the Honeywells, will display room temp over desired temp. check that, if it wont let you switch temp than buy a new one, if you dont have a heat pump a new cheap stat is around 20.00.

Dec 31, 2008 | Honeywell Programmable Thermostat Heater

2 Answers

-AC appears in the display of chronotherm III

I have had the same problem- twice. It was a similar but different problem each time. The -AC means the ac control voltage isnt making it to the thermostat. In my case both times it was a switch in the control circuit that wasn't closing properly. The easiest was the front cover switch. If the front cover is removed from the furnace or has vibrated loose, the switch will open, preventing the furnace from running. The other instance I ran into was a flow switch on the exhaust blower which ensures the there is flow OUT the chimney. The switch wasn't functioning, so the furnace wouldn't start. The blower would come on for a short time, but the burners wouldn't light.

Hope this helps,

Dec 12, 2008 | Honeywell Programmable Thermostat Heater

1 Answer

Honeywell Chronotherm III

Try this link:

It looks like there are a variety of model numbers for the Chronotherm III. Hopefully you can locate your model number.

Dec 17, 2007 | Honeywell Power Humidifier: Furnace...

Not finding what you are looking for?
Heating & Cooling Logo

Related Topics:

321 people viewed this question

Ask a Question

Usually answered in minutes!

Top Heating & Cooling Experts

Paul Carew

Level 3 Expert

3390 Answers

Ronny Bennett Sr.
Ronny Bennett Sr.

Level 3 Expert

6927 Answers


Level 3 Expert

83557 Answers

Are you a Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides