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QUESTION: I have a Bryant heat pump with auxiliary heat. I use strictly gas in the winter no heat pump whatsoever. my problem is it works fine but runs for about 8 minutes then off for 3 to 4 then back on and so on meaning it repeats over and over but works fine. on occasion I will also note that the blower motor runs continuously and will not automatically go off even though all limits are satisfied  but the furnace will not kick back on a couple of occasions. after turning thermostat off and braker off it clears the code and continues described above. the old thermostat when out I replaced it with a new Honeywell model . I had the wiring checked and the programming checked by an HVAC tech. I have checked all voltage & is fine both low and high. filter is fine there are no obstructions. blower motor does not get hot also the exhaust motor seems to be okay but does get a little warm. it is a Bryant 80 percent efficiency I have gone over thermostat programming many times. I keep the unit an immaculate condition I was a tech in a former life (20 yrs ago). I've trouble shooted everything under the Sun I'm out of ideas.  again it appears to work fine it just cycles on and off correctly . I live in central Ohio in every sense lady had high winds if that helps.

ANSWER: Mel,



You do not mention if your system was working fine with the old stat. If it was  then your problem is in the new stat, if your blower stays running all this time and your positive your calling for heat ,to me would be another indication your stat is the problem. Try bypassing the stat by jumping R to G to Y at the stat,( you can also jumper R to O which should energise your reversing valve coil. The RV coil should click when it's energising ) which should bring on you blower fan and outdoor unit let it run , if it continues to run over 15 minutes or so then your stat is the problem then remove jumper wires and if the fan shuts off and outdoor unit off also you know where your problem is. Also you do not mention if your A/C works OK with the new stat. You mentioned you had a HVAC tech. check wiring, that person was unable to troubleshoot your system ? Need to double check your new stat is compatible to your systems.

---------- FOLLOW-UP ----------

QUESTION: my apologies...no the old thermostat had gone out completely that's what lead me to check the 24 volt circuit first and found no problem there. so I started troubleshooting the 120 an all of the components there and didn't find anything. I probably should just try another thermostat since it does work fine and everything fires and goes according to sequence startup but just cycles too much. it almost reminds me of the old mercury stats with a heat anticipator set wrong but I would imagine solid state would take care of that.  the blower has only stayed running a couple of times but the temperature would drop for 5 degrees before I noticed and then I did a reset.

I sincerely appreciate your prompt response just wanted to make sure I wasn't crazy.  out of the box stuff does fail you just don't like to think it LOL but I've spent enough time troubleshooting thank you again.

Answer
Mel,

I understand that you changed your old stat because it failed, my question was did your system work fine prior to the old stat failing , if it did  then it's your new stat. Also what happens if you raise the new stat 15 degrees higher than room temp. does the heat pump cycle every 8 min. if it does not then your stat differential is probably set 9 from the factory 0 real close. The old mercury stats had a aprox. 2 degree differential, yours may have a one degree or even less so it cycles sooner. I would jump out the R to Y to G , if it runs without stopping it your t-stat. Check the differential setting ,some t-stats you can widen the diff.

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40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.

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Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

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Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

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