TROUBLE SHOOTING EVAPORATOR COMPONENTS
FAN TERMINATOR
The fan terminator is located on the suction line and is
covered by cork tape. The terminator is closed at 30
degrees F (-1 C) and opens at 60 degrees F (16 C). If the
terminator is suspected as the problem, the evaporator
coil must be cooled to 30 degrees F (-1 C). This can be
verified by placing the unit in the Auto Chill Mode
followed by a 5 minute waiting period. After 5 minutes,
push and hold the 2 key on the keyboard for 5 seconds.
The RTD Temperature Screen should appear (Figure 21).
Observe the temperature of COL 1 and COL 2. If the temperature of the coils is under 30 degrees F (-1 C)
and the fan(s) are not turning, the fuses, the terminator, the wire from the terminator to the fan, or the fan
motor may be defective. Disconnect the plug from the fan and with a multimeter set to the VAC scale, check
across the 2 outside pins. There should be 208/240VAC. If the correct voltage is present, turn OFF the power
and plug the fan in. Turn the power ON. If the fan does not run, the fan motor is defective and needs to be
replaced. If there is no voltage present, disconnect the wires from the terminator and with a multimeter set to
the OHMS scale, check for continuity through the terminator. If there is no continuity, the terminator is
defective and needs to be replaced.
NOTE: IN AN EMERGENCY, THE UNIT CAN BE OPERATED WITH THE FAN TERMINATOR BYPASSED,
BUT ONLY UNTIL A NEW PART IS RECEIVED AND INSTALLED. AT NO TIME SHOULD
BYPASSING THE TERMINATOR BE A PERMANENT SOLUTION.
DEFROST TERMINATOR
The defrost terminator is located on a plate, usually above the evaporator coil. The terminator closes at 30
degrees F (-1 C) and opens at 60 degrees F (16 C). If the terminator is suspected as the problem, verify the coil
temperature is at 30 degrees F (-1 C) by accessing the RTD Temperature Screen (Figure 21). If the coil
temperature is 30 degrees (-1 C), turn the unit OFF. Access the 2 evaporator heater leads and disconnect. With
a multimeter set to the VAC scale and connected to the heater leads, place the unit into defrost. There should
be 208/240VAC present. If not, turn the unit OFF, and disconnect the defrost terminator leads. With a
multimeter set to the OHMS scale, test for continuity through the terminator. If there is no continuity, the
terminator is defective and needs to be replaced. If the defrost heater is suspect, disconnect the heater leads
and with a multimeter set to the OHMS scale, test for continuity through the heater.
RTD COIL SENSOR, PRODUCT PROBES, AND AIR SENSOR
The RTD coil sensor, located on the suction line and covered by black cork tape, can be tested by
placing the sensor in an ice water bath. With a multimeter set to the OHMS scale, there should be 100
OHMS resistance at 32 degrees F (0 C). The product probe and air temperature sensor should be tested in
the same manner.
NOTE: WHEN REPLACING ANY OF THE SENSORS OR PRODUCT PROBES, BE CERTAIN TO CONNECT
THEM TO THE CORRECT PLUGS ON THE CPU BOARD.
12.
UP: 72.0 COL1 23.4
MID: 72.0 COL2 22.4
LOW: 73.4 CPU: 72.7
AIR: 74.4 (F) EXIT=D
Figure 21
(16 pages)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals