Dometic roof top ac/heatpump

[ginaandharol]

My ac started acting weird last week. I put my Comfort 5 button thermostat in cool mode on the front ac. It works for about a minute after the compressor kicks in, then the heat starts coming in. Somehow the switching valve(?) reverses and the cold air is exhausted outside and the hot air comes inside. The back unit works fine. I removed the cover on the ac and looked at the wiring, when the unit first starts, a solenoid on the compressor clicks, which I assume is what controls whether it is in heat pump mode, or cool mode. I'm not sure if the solenoid stays closed or not, or if that even has anything to do with my problem. It's starting to get hot, and I'm not near a service center. Help.

[ginaandharol]

I went to JustAnswer and a tech named Darryl worked with me and we figured it out. The wires to the solenoid on the switching valve were stretched tight between the solenoid and the PC board, over the years with the vibration of the ac, the wire broke inside the insulation right at the solenoid. That's why the ac would work and then switch to heat intermittently. When I checked the voltage at the PC board with the unit on ac, it had 110v. I couldn't check at the solenoid because the wires go right into the unit. I put my finger on the solenoid and could feel the solenoid click in when first turning on the ac, but couldn't feel it release when it switched to heat. I finally cut the wires and removed the solenoid. I put my ohm meter on the ends and had a 260 ohm reading which is what it is suppose to be. I then inserted the skinned wires into an extension cord, I inserted the blade of my screw driver into the hole of the solenoid and it "grabbed" it, I wiggled the wires at the entrance to the solenoid, and IT LET GO of the screwdriver. Aha, I could get the solenoid to work and then not when moving the wires. I temporarily used epoxy to hold the wires in place, but will order a new solenoid. DON'T TRY THIS AT HOME IF YOU AREN'T COMFORTABLE USING HOT 110v ELECTRICITY. I AM A RETIRED ELECTRICIAN!!!