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Section 9
Quick Tips
9.1 Mechanical Control No Compressor.
Turn power off and check in the following order.
1. T-stat test . Continuity
2. Selector Switch test. Continuity
3. Overload & Compressor test.
9.2 Comfort Control No Compressor and / or Fan.
First select high speed fan, not auto fan mode on the t-
stat. If the fan runs a temperature sensor could be the
problem.
1. Unplug ALL temperature sensors wait; 3 min
utes and try again.
2. If multiple zones, unplug all other zones; wait
3 minutes and try primary zone alone.
3. Try a different DC power source and try again.
If one of the 3 sensors has a short it may not allow the
compressor or fan to come on. A shorted ambient sen-
sor could cause very erratic operation. The DC wires to
the control system should be a dedicated line. There has
been reports of things in the coach sending out RF ( Ra-
dio Frequency ) creating erratic operation or no operation
at all. Disconnect DC power to all the components in the
coach and run a dedicated straight line DC to the CCC
control system and try again.
Always do a reset on the Comfort Control when no or er-
ratic operation exist. Reference page 19 for reset.
Analog control test for Compressor, Fan speeds and Fur-
nace. All analog controls have 6 or 7 wires from control
board to T-Stat. This test will by-pass the t-stat and har-
ness in the wall. Disconnect all wires leaning from power
module to thermostat. Check incoming AC and DC to con-
trol board for proper voltage. Follow the tips listed below.
When the ground wire from the control system is jumped
to the listed wire, it should close the relay and activate
that function. The thermostat provides a ground to close
a relay. Using the wires from the control to test the follow-
ing.
Green (ground) to the proper wire should activate the
function from the control system. When Green to Orange
is activated the heat strip should come on if unit has Heat
strip. When Green to Orange on units with heat pump is
activated, this will send voltage to the reversing valve. If
the item ( fan, compressor, furnace, heat strip) comes on
the control module is OK the problem lies in the wires or t-
stat. If there is still a problem go to control board testing.
Reference Dometic bulletin A27-8C.
9.3 Analog Tips
Green plus Tan = Low Fan
Green plus Tan & Blue = High Fan
Green plus White = Furnace
Green plus Yellow = Compressor
Green plus Orange = Heat Strip
Green plus Orange = Heat Pump
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