I just had new evaporator coils and a new thermostat installed. This was all due to a leak in the evaporator coils. Now I have nice new shiny aluminum coils. Once the system was filled with gas and the AC fired up it was amazing. It was cooling the house like it hadn't in years. Really cold air blowing out. The issue is that now the heat doesn't "fully" work".
Here is what I mean by "fully". When I switch the thermostat to heat and then crank the heat up a few degrees higher than the room temp I can hear the thermostat click and then the heat starts blowing. A quick check shows the air is coming out of the vents at about 80 degrees F (about 5 degrees warmer than room temp). When I walk outside to the heat pump the pipe going in is hot to the touch. To hot to keep your hand on it. So all seems well and good until about 4 or so minutes later. At that point the air suddenly starts blowing cooler out of the vent (about room temp air) and eventually the pipe outside that was VERY hot starts to cool down. Not cold like when the AC is on, but not hot at all.
My AC guy isn't sure what is going on. He has replaced the thermostat once already. The outside unit is a Trane. Before this repair, while the AC was not cold the heat worked just fine. Now I have a AC that is amazing and no heat. Is it possible the wires are incorrect in the thermostat? The replacement thermostat (Honeywell TH3210D) does not have the exact same wire labels as the old one (Simple Comfort SC2200). The old thermostat has
B O W2 G E Y1 Y2
The new thermostat has
E AUX Y G O L R B C
Unfortunately I don't have a picture of the old way it was wired, but the new one has wires going into
E Y G O R
There are no jumpers.
Any ideas? I would think if the compressor was having an issue that the cold would not work either. It also is strange that when the heat first comes on it appears to work, but then stops a few minutes later.
Best Answer
You need to find a real heat pump service person. It's hard to trouble shoot a system without being there. Did he put in a correct refrigerant charge amount and the correct type refrigerant? Is the new coil the same size (BTU) capacity as the old coil? Does it have the same type expansion valve? Has anyone used gauges, if so what do the pressures do when the unit heats then begins to cool off? Does the compressor change it"s tune level? What happens to the temperature of both the small and larger line when this heating and cool off happens? It's not rocket science you just need to know what is happening with the system and what should be happening at any given time in the "on cycle".