5-2
Condenser Fan and Evaporator Fan Rotation
Electrical Maintenance
CRR-20 & CRR-40, September 1999
• If the compressor restarts and operates for 10 minutes
without an overload condition, no alarm is recorded.
• If the overload still exists after 5 minutes, the controller
turns the Alarm LED ON. Also, if the overload condi-
tion occurs 3 times within 30 minutes, an alarm is
recorded. Pressing the ALARM key on the controller
will cause alarm code 10 (High Refrigerant Cutout) to
appear on the right display.
• Unit restarts when the overload condition is corrected
(reset) as long as power is available.
To test the switch, rework a gauge manifold per “High
Pressure Cutout Manifold” illustration.
High Pressure Cutout Manifold
1.
Connect the manifold gauge to the compressor discharge
service valve with a heavy duty, black jacketed thick wall
#HCA 144 hose with 6024 kPa, 60.24 bar, 900 psig work-
ing pressure rating.
2.
Operate the unit in Cool by performing an REFRG/FC HI
(full cool with high speed evaporator fan) test from the
Test Menu of the
µ
P-D controller.
3.
Raise the discharge pressure of the compressor by block-
ing the condenser coil airflow. Temporarily cover the
compressor compartment, control box and power cord
storage compartment with cardboard to reduce condenser
coil airflow. This should increase the discharge pressure
enough to cause the switch to open. When the switch
opens:
• The Alarm LED should turn ON.
• The compressor and evaporator fans should STOP
immediately.
• The condenser fan should continue to operate.
NOTE: The discharge pressure should never be
allowed to exceed 2,760 kPa, 27.6 bar, 400 psig.
4.
Be sure to remove the cardboard installed in step 3.
NOTE: To clear the HPCO alarm, press the
ALARM key on the controller. Press the DOWN
key until ENTER flashes in the left display. Then
press the ENTER key. The Alarm LED should
turn OFF and the unit re-start.
WARNING: When alarm codes are cleared by
pressing the ENTER key, the unit will start auto-
matically.
If the HPCO switch fails to stop compressor operation, replace
the switch and repeat steps 1 through 4.
Condenser Fan and Evaporator Fan Rotation
Condenser Fan
Check for proper condenser fan rotation by placing a small
cloth or sheet of paper against the condenser fan grille on the
front of the unit. Proper rotation will blow the cloth or paper
away from the grille. Improper rotation will hold the cloth or
paper against the grille.
NOTE: If unit operating conditions do not require
condenser fan operation, check the condenser fan
rotation by performing an AMPS/CFH (high speed
condenser fan) test from the Test Menu of the
µµ
P-D
controller.
If the condenser fan is rotating backwards, refer to the
unit wiring diagram to correct fan motor wiring at the fan
motor junction box or condenser fan contactor. To correct
improper fan rotation, reverse any two fan power cord leads at
the condenser fan contactor (disconnect power supply before
reversing leads). DO NOT move the CH ground wire.
Evaporator Fans
Visually inspect the evaporator fan blades for proper rotation.
Arrows located on the underside of the fan deck indicate the
correct direction of rotation.
NOTE: Check both High and Low Speed evaporator
fan rotation by performing an AMPS/EFH (high speed
evaporator fan) test and AMPS/EFL (low speed evap-
orator fan) test from the Test Menu of the
µµ
P-D con-
troller.
If an evaporator fans rotate backwards on one or both
speeds, refer to the unit wiring diagram to correct motor wiring
at the fan motor junction box or evaporator fan contactor (dis-
connect power supply before reversing leads). (DO NOT move
the ground wire which is labeled CH.)
NOTE: Evaporator fan motor wires EF1, EF2 and EF3
are used on LOW SPEED fan operation. Wires EF11,
EF12 and EF13 are used on HIGH SPEED fan opera-
tion.
NOTE: To diagnose the controller phase selection
system if both the condenser fan and evaporator
fans are rotating backwards, see the Diagnosis
Manual for Thermoguard
µµ
P-D Microprocessor
Controller, TK 41230.
Содержание CRR-20
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