Rear AC problem

[ktm500mx]

hi, I have a rv with 2 duotherm ac units tied into a thermostat.
the front is fine the thermostat seems to work ok. its the rear unit
is not blowing cold air. this rig is new to me and I am very handy
I am looking to ask if there are some common problems to look for.
thx in advance. mike

[Ray,IN]

You are aware you have 2 "zones" on the thermostat. Each controls 1 unit, with a 2 minute delay between changing some settings and unit responding. To download the service and installation manual for your unit go here: Aero-Rv.com - Aerolite Ultra Lite RV Travel Trailer and Expandable Hybrid Campers
Select HVAC,> scroll down to your brand/model_>.

[RV Wizard]

Set the fan for zone 2 on "Auto". When the T'stat calls for cooling in that zone, the fan will come on. After a couple of minutes you should know if the compressor is running and will cool. Do you have a clamp on amp meter and are comfortable in checking amperage at the 120vac distribution panel? If so, check the amperage. After about 5 to 8 minutes you should have about 12-13.5 amps depending on model and fan speed. Let us know what you find.

["007"]

With your zone set to #2 and Mode set to cool rear AC will come on after 2 min delay. In your bedroom you should see a white plastic cage, size of a quarter on wall. In the cage is a thermistor that feeds back to main control. Make sure its in the cage and not fallen down inside wall and wire connectors are tight.

[ktm500mx]

I checked the thermistor its ok the unit is blowing cold air but when trying to set zone 2 the thermostat go blank. the thermostat is a 4 push button and one on/off switch duo therm thermostat. is this normal or do I have a communication problem between the theromstat and the ac unit?
thx Mike

["007"]

Mike I would check the tel cord wire that connects between rear AC and thermostat.
Maybe loose or dirty connection.