2006 Tioga A/C - Fan - Heat not working

[indymeesh]

Out of winter storage A/C or fan did not come on with Gen or shore power. Everything else worked. Magically one night the fan came on with shore power. Ran the A/C and fan cycles for a week. All ok. Also tested heater and that worked and cycled.

Went on a trip and again no A/C or fan or heat. Checked all the breakers and pulled each fuse to make sure they were good. Deep cells were charged. Checked in the wall behind the thermostat and no wire / mice issues these.

Thermostat was 2 years old but I bought a new one and installed it. Tested and got power to all the wires using the blue as negative (Coleman Mach tech suggestion). Still no go. Fuse was good also.

Replaced the 8330-752 controller in the roof A/C unit (hard to do) and still nothing. Had power to the controller.

Have Appt at the RV place June 21 but thought I would post this just in case someone had an idea what might be the issue.

Thanks in advance, Mike

[MrMark52]

Intermittent power issues take some tenacious investigation -

Disconnect 120 volt power to your coach.

Open the breaker panel, remove the breaker cover plate to access inside of the breaker panel.

Check all wire clamping screws for being tight and inspect all wiring/wiring connection points for overheating or burning. Repair or replace as needed.
Thermostats operate on low voltage that usually originates in the unit and feeds down to the thermostat. Compressor’s and fan motors are powered with 120vac.

Get yourself a wiring diagram/schematic for you AC units - that will be a good start. If your unit is a heat pump, then the wiring diagram/schematic will help, but if your heat is driven off a common thermostat but a separate unit like ours are, then it complicates things - especially when you have power at the thermostat. An LP MoHo/rv furnace usually works off of 12vdc only.