Electrical Maintenance
57
Condenser/Evaporator Fan
Rotation (Electric Standby
Operation)
The condenser and evaporator fans are belt
driven. On electric standby operation, check for
correct fan rotation by placing a small cloth or
sheet of paper against the condenser fan grille on
the front of the unit. Correct rotation will hold the
cloth or paper against the grille. Improper rotation
will blow the cloth or paper away from the grille.
To correct check motor and motor contactor
wiring as per wiring diagram, incorrect power
cord wiring may give an alarm code 38.
Defrost Air Switch Checkout
and Adjustment
Before testing or adjusting the air switch, check
the clear plastic tubing and black plastic tubing to
the evaporator coil. Make sure they are not
obstructed or crushed. Check the probes in the
evaporator housing to be sure they are in proper
position, and make sure they are not obstructed.
1. Remove plastic sensing tubing from both sides
of the defrost air switch.
2. Disconnect one wire at switch terminal.
Connect test light or continuity tester to the
two terminals used on the switch.
3. Install test equipment (see Tool Catalog) onto
the hose fitting on the side of the air switch
stamped BLACK.
4. Pressurize the hose until the continuity tester
indicates a completed circuit. Now read the
dial of the test gauge. This is the setpoint of
the air switch (correct reading is 1.5 ± 0.08 in.
[38 ± 2 mm] H
2
O). Release the pressure.
5. If the switch is out of calibration, pressurize
the hose again until the tester indicates 1.5 in.
(38 mm) H
2
O. Adjust the screw clockwise or
counterclockwise until the switch closes and
the continuity tester indicates a completed
circuit with the gauge reading 1.5 in.
(38 mm) H
2
O. Release the pressure.
6. Repeat test procedure several times to be sure
the setting is correct.
1. Magnetic Pressure Gauge
2. Squeeze Bulb Tool
3. Continuity Tester
Figure 28: Testing Air Switch
1. Adjustment Screw
Figure 29: Air Switch
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