7
−
40
62-11389
Alarm
NO.
Steps
Alarm/Cause
Corrective Action
55
CHECK DEFROST AIR SWITCH
•
TRIGGER–ON: The defrost air switch has called for a defrost cycle within 8 minutes of a defrost
termination for 2 consecutive defrost cycles. (The air switch contacts were closed continuously for
15 seconds before the defrost cycle was started.)
•
UNIT CONTROL: Engine and standby Operation: alarm only. While this alarm is active, the defrost
air switch will NOT be used to initiate a defrost cycle; however the Defrost Timer will initiate a
defrost cycle 90 minutes after the alarm comes on, and the manual defrost switch will remain
operative.
•
RESET CONDITION: Auto Reset when defrost cycle terminates correctly, and the air switch does
not call for a defrost cycle within the 8 minutes following defrost termination, or alarm may be
manually reset via keypad or by turning the unit off, then back on again.
NOTE: Follow the steps below until a problem is found. Once a repair or correction has been made, the active
alarm should clear itself (see reset condition above). Operate the unit through the appropriate modes to see if
any active alarm occurs. Continue with the steps below as necessary.
1
Check Condition Of Refrigerated Compartment & Load
a. Check condition of refrigerated
compartment doors & seals.
Doors must be closed, and door seals must seal and
prevent entrance of outside air.
b. Check condition of evaporator.
Check for blockage sufficient to cause an air pres-
sure differential across the coil great enough to close
the contacts of the defrost air switch.
Coil must be free of ice following defrost.
c. Check condition of product.
If product is warm and moist, frequent defrost cycles
can be expected.
2
Check Switch Wiring
a. Inspect switch & connector pins &
terminals.
No physical damage to switch.
No damage or corrosion in connector.
b. Check switch circuit. (See wiring
schematic Section 10.)
Check wiring from switch to microprocessor terminal
2MP6 is not shorted to a power source, providing a
false signal.
3
Check Defrost Air Switch, Defrost Circuit and Tubing
a. Perform testing and reset switch if
required.
Refer to Section 8.8.9 page 8
−
31.
