I have a TRANE XL 1200 heat pump. When in the heat mode the air handeling coil freezes up, enough to block the air flow. I can turn the heat pump off and leave the air handeling unit air circulating fan on and get the ice melted. After 30 minutes or so I can turn the heat pump back to the on poslition and the unit works normally for several hours. It then freeses up again.


What is the most likely cause of the problem?

Bob

acetc

Sounds like it is not going into the heating mode, could be a bad defrost timer, reversing valve or reversing valve solenoid coil, defrost timer. Mike

Stubby74

I agree with acetc...could be rev. valve.....could be a restriction in your refrigeration lines...like debris, kink in line, etc. possible stuck contactor. Check your filter as well...but a unit freezing up inside is usually meaning it is going into AC and not having enough air flow and will freeze up, dirty filter will slow the air flow down...but your problem has alot of possibilities....make sure your fan is coming on when you turn your HP on....Ref. Charge could be a problem also...Good luck...

T-Top

Your not in heating mode if your evaporator coil is freezing up. Lack of air flow in the fan coil will only make the coil hotter to keep it from freezing. I agree with acetc the reversing valve is stuck or you have a defrost board bad or a wire shorted to 24 volts keeping the reversing valve energized . One question did you change your thermostat out recently.