I have a 20+ Dico programmable thermostat and an intermittent Trane heatpump. Outside fan runs, Freon is okay, inside coils frost up and hear the backwash but no cooling. Shut off thermostat for an hour or two, we're back to cooling. Replaced with a Honeywell thermostat. Cooled for a few hours and stopped working. Re-installed Dico thermostat and live with shutting heatpump off every few hours or days. Serviceman wants to install their thermostat and hope the heatpump fails while they are on site. Any suggestions