Any Honeywell thermostat experts out there? Freezing in Massachusetts...and it's 90 out!

Hi there,
I have what looks like an ancient Honeywell Chronotherm III running my heat/ac system here at home. For the last 2 years it has operated without problems, however over the last couple of days it has started to act up.
It seems that it will no longer hold the temperature when the system is on the A/C. I set the slider to "Cool" which engages the A/C, then press hold and select the desired temperature. Usually this would turn the A/C on and off automatically to maintain the temperature I had entered. Not any more...
What happens now is that the screen displays:
1:18pm -AC
(replace 1:18pm with whatever the current time is)
The A/C is running, but will continue to run until I go down to the basement and shut it off at the shut-off, (regardless of the temperature setting on the thermostat) otherwise we'd be living in an icebox by now.
I've tried changing the batteries in the thermostat but to no avail...does anyone have any ideas as to what I can try next, any help would be very gratefully recieved!
Thanks in advance!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I think the procedure is to set the temperature you want THEN press hold. That's the way mine works. Do you have the owner's manual for the stat? If not contact Honeywell for a copy.
Frank

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Might be a sticky relay or contactor in the AC. Time to call a service guy.
Something to test. When it starts to get too cold, switch the thermostat from "cool" to "off". Or to "heat". If the AC continues to cold, you know it's not a thermostat problem.
--

Christopher A. Young
You can\'t shout down a troll.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for the hint, I've tried this and indeed the AC continues to crank...
Can you give me a rough idea of how much I might expect to pay to get a "sticky relay or contactor" fixed here in the greater Boston area - just so I have an idea and don't get bent over for it.
Thanks again for the help, much appreciated.
Stormin Mormon wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.