Originally Posted By: bking
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I thought this was important, it looked like a problem to me and several local HVAC techs that I called did not know about it and said the defrost boards were bad. Luckily, I did not let them work on it.
Both Units are 2-3 years old SEER 13 rating
Info on newer PURON refrigerant (carrier/bryant) normal operation:
Info came from Field Engineer at Bryant.
With heating mode and a "low load condition" ie. around 40+ degF, unit will appear to be in defrost cycle due to outside fan shutting off and compressor still running, very often occurrence (every 5-10 min).
This is normal programmed head pressure regulation and the unit has not energized the reversing valve. This is necessary due to the higher head pressure that the puron (not R-22) operates at while utilizing the same wall thickness refrig. lines as R-22 pressures.
This feature is called Pressure Guard.