GMC 1976 ZEO 6083 Maintenance Manual page 747

24E- 8
ROOF MOUNTED AIR CONDITIONER
Figure 12-Thermostat Sensing Tube (Typical)
Problem
Remedy
c . Thermostat (figure 12).
c. The thermostat will open around 70°F .
(21 .1°C .) so be sure the temperature is warmer
than 70°F . (21 .1°C .) before checking the power
out. If power is available at the black wire ter-
minal, there should be power out of the terminals
for each switch position . Power should be received
in all cooling positions . With the power off and
the leads disconnected, check the switch for con-
tinuity with an ohmmeter or self-powered test
light. For a positive continuity check of the
thermostat, put the sensing probe in warm water
(100°F .) (37 .8°C .) and check for a closed
circuit. Then check for an open circuit at all
dial settings with the tube in cold water (50°F.)
(10°C.) .
Problem
Remedy
4. Fan Motor (figures 1 and 2) .
4. Disconnect the leads to the fan motor at the
box and check for continuity from the white wire
through each of the other leads. If there is an
open circuit through any winding, replace the
motor. Check for shorts to the case by connecting
the ohmmeter between the case and each power
lead . If there is continuity, replace the motor.
If the fan runs but not at full speed, check the
motor capacitor as described later.