Heating, Air Conditioning, Fridge, HVAC/Problems w/ thermostat


Hi. We had replaced an old, mercury thermostat with a Honeywell 75000D series digital programmable thermostat (RTH 75000D 1031) about 3 years ago. In that time the AC has not worked properly...actually at all. We purchased the house in 2008 and the heating unit/heat pump/AC had been installed about 5 years previously and we do not have the manuals for them. With the old thermostat the AC worked fine, no problems...and of course we got rid of it after we installed the new thermostat, doh!

Here's what I have aside from the thermostat:

Lennox Heating unit/heat pump:  CB30M-41-1P
(from what I can find it's a multistage unit)
Jumper noted on RC-R and W2-Y2 (Aux-E)

Lennox AC unit: HPXA15-036-230-02

We've had an HVAC tech come out 3 times in the three years, he's found no issues with the units or the thermostat itself. The freon was just a little low on the first visit so he charged it up again and it is still fine. The next visit (if there was to be one) would likely be changing out the thermostat.

Now, according to the paperwork from Honeywell the thermostat should be compatible with the setup that we have.

So I have 2 questions actually:

1. Is this the correct thermostat for this set up? Should it be working?

2. Any ideas that I can look at that may leading to the problem of no AC since everything checks out fine?

We've already dumped nearly $400 in the two visits. If it's something relatively simple that I can check on before having to call the tech back out I'd like to see if I can do it myself. Thanks.

Thank you for your request.  Unfortunately our expertise is with Major Home Appliances only.  This site puts Home Refrigeration and HVAC in the same category.  This would include washers, dryers, refrigerators, microwaves, dishwasher, ranges and ovens.  If you need help with any of these appliances, feel free to submit another request.  For your problem, please request assistance from a AllExpert with experience in the HVAC service field.  If you ever need assistance with Major Home Appliances feel free to come back and initiate another request.  Visit our Website at http://www.affordableappliance.com or e-mail us directly at sales@affordableappliance.com

Thank You for your request,
Eric & Ann Campion

Heating, Air Conditioning, Fridge, HVAC

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Eric Campion


We have been repairing appliances for over 36 years and have owned our own business for the same. We can help in any or almost all complaints or at least give you some intelligent input to help you make rational decisions. If maxed-out... You may visit our website at http://www.affordableappliance.com for quicker service.


30 years owning our business and repairing Major Home Appliances

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36 Years of Working on Major Home Appliances and selling parts. Our office staff is top notched and is supervised by My Wife Ann who is also very experienced in the Major Home Appliance Service and Part Sales Business

My credentials can be viewed on my website at http://www.affordableappliance.com

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