Heating, Air Conditioning, Fridge, HVAC/Trane XL15i vent system

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QUESTION: Hi,
We have Trane XL15i heat pump which is about 7 years old.  We didnít have a problem during past summer (we actually didnít have any problems with it at all). When temperature outside dropped, vent system turns on and then immediately turns off. The thermostat is sated up on 70˚and heat pump is turns on every 6 min. and keeps air 70˚, but propeller in vent system turns on every 3 min. Itís just drives me crazy.
Could you please help me to find out what is wrong with this vent system?
Thanks.
Natalia.


ANSWER: Natalie,

Propeller, meaning blower motor ? Outdoor temperature has nothing to do with the indoor blower turning on off every 3 minutes , unless it's miss wired, or you have control issues. Do you have an outdoor sensor that would affect your Heat Pump operation ? So when the heat pump turns on every 6 minutes, what does your blower fan do? still turn on every 3 minutes or does it run the 6 minutes along with your outdoor unit ( which it is suppose to do ) If you lower your thermostat 10 degree below room temp. does your blower fan run every 3 minutes? Have you ever had a Preventive Maintenance check up of your Heat Pump in the last 7 years ?

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

QUESTION: Yes, propeller means blower motor. When the heat pump turns on every 6 minutes, blower fan still turns on and then immediately turns off every 3 min. When temperature inside room reaches sated up temperature in the thermostat, blower is not turns on anymore. We donít have any outdoor sensors; just another unit for the second floor. We usually have a PM at least once a year but not this year yet.

Answer
Natalie,

So when the temperature in room is not calling for heat your blower fan stays off ?, Your amount of run time ( every 6 minutes ) with a heat pump, depends on outdoor temp. the colder the outside temperature the longer your HP will run, that is a fact.( it can't stay at 6 minutes if it's real cold outside )  If in fact the thermostat is satisfying every 6 minutes then your blower should run as long as the t-stat is calling, if the blower is shutting off every 3 minutes ( you don't mention how long it's off before it comes back on,you mention it immediatly shuts off ,but you don't state for how long it's off before it restarts ) or if the outdoor unit is still running all this time.( which it should be ,due to the t-stat still calling for heat )Try moving the fan switch at the t-stat to ON from auto, your blower motor fan should run 24/7 even if heat or cool are not calling , does the fan shut off and on?? or stays running. if your motor does not, then you have issues, possible tripping on an internal motor overload,or you have some wiring issues . You would need to be electrically/mechanically inclined to further check. You would need to determine if the blower fan relay is losing 24 volt ac ,while it's still calling for heat or if it's your motor. Is your air filter clean, I have seen a plugged air filter damage a blower motor, because the motor overamps and shut down, due to the restriction of the air filter or any obstruction in the return duct.If your outdoor unit still runs when your indoor fan shuts off that is not a good situation, as the internal refrigerant pressures rises and can cause many problems. I would call for service. Leave your blower fan in the ON position until then.  if it runs OK.

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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.

Education/Credentials
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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