Heating, Air Conditioning, Fridge, HVAC/Miller/Nordyne Heatpump issues


I have a 4 month old Miller heat pump that will satrt up in what appears to be the defrost mode, and will run for several minutes blowing COLD air before starting to blow heat. The unit runs for sometimes an hour or more at a time. When it does put out heat it is warm, but will sometimes switch into defrost mode, condenser fan stops compressor runs, during operation while indoor blower continues to run blowing cold air. Any suggestions as to what the problem could be ?


All this should be covered under warranty, including labor. Sounds like possible defective defrost board if it starts everytime in defrost mode, would not be unusual to start in a defrost mode once in a great while. You do not mention if you have electric heat as the second stage on your t-stat. Possible miss wire somewhere.possible your in A/C mode also instead of heat mode. Heat Pumps put out typically warm heat not hot.Your defrost cycle could be set wrong, typically once the defrost sensor  mounted on a outdoor coil bend closes your system goes into defrost. Depending on your area it could be set at 30 minutes ,or 45 or 60 or 90 minites.So as you state " The unit runs for sometimes an hour or more at a time " if the defrost pin is set to 30 minutes then every 30 minutes of run time it will initiate a defrost ( as long as the defrost sensor is closed )  Also when a Heat Pump starts it does not blow instant warm air it takes a few minutes, especially if it's cold outside.Possible your refrigerant charge is not correct. ( you having a split system ) possible your defrost pin setting needs to be set to a higher setting, possible nothing is wrong with your system.

In closing call the Company who installed it , if you went with a Professional Contractor all should be covered, parts and labor.

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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.


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.

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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