In the summer, when the vinyl wire insulation was warm and flexible, wire flexing would absorb the vibration. But in the winter, the vinyl insulation would get stiff and transmit the motion to the connector. The stress would concentrate at the point where the crimp met the receptacle. Repeated bending back and forth broke the connectors off. I then realized that if I needed to replace another connector, I should replace the wire with one long enough to include a loop to absorb the motion.
All heat pumps, including this one, contain a crossover valve. This switches the flow of refrigerant so that the inside coil cools in summer and heats in winter. Such valves are opened (for cooling) by an external solenoid and closed (when heating) by an internal spring. However, in the winter a heat pump alternately runs heating cycles (to heat the house) and cooling cycles (to heat the outside coil to melt off the rime ice which forms on it).
This unit had the flaw that the spring action was so weak and the piston so sluggish that in cold weather it could not restore to house heating after a cycle of ice melting. The colder it was, the more often it would stick. Usually, when I felt cold air blowing from the ducts for an excessive time, I could reset it by cycling the thermostat. But the problem became worse and the crossover valve had to be changed. Lacking an HVAC license, I had to pay for this one: $500.
All of this was hard on the compressor, so four years later (also on a cold winter day) it failed. Its motor ran fine, but the valves weren't working right. Trane had given up on this unit by then, so I bought another brand.
This entry was submitted by Larry Marks and edited by Rob Spiegel.
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