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5.14 COIL CLEANING
5.14.1
Evaporator Coil
The use of recycled cardboard cartons is increasing across the country and these cartons create much more fiber
dust during transport than new cartons. The fiber dust and particles are drawn into the evaporator where they lodge
between the evaporator fins. If the coil is not cleaned on a regular basis, sometimes as often as after each trip, the
accumulation can be great enough to restrict air flow, cause coil icing, repetitive defrosts and loss of unit capacity.
Due to the washing” action of normal defrost the fiber dust and particles may not be visible on the face of the coil,
but may accumulate deep within.
It is recommended that the evaporator coil be cleaned on a regular basis, not only to remove cardboard dust, but also to
remove any grease or oil film, which sometimes coats the fins and prevents water from draining into the drain pan.
After being wet and dried several times, cardboard fiber particles can be very hard to remove. Therefore, several
washings may be necessary.
a. Remove rubber check valves (kazoo) from drain lines.
b. Spray coil with a mild detergent solution such as Oakite 164 or any good commercial grade automatic dish-
washer detergent. Let the solution stand for a few minutes and reverse flush (opposite normal air flow) with clean
water at mild pressure. A garden hose with spray nozzle is usually sufficient. Make sure drain lines are clean.
c. Run unit until DEFROST mode can be initiated to check for proper draining from drain pan.
5.14.2
Condenser Coil
Remove all foreign material from the condenser coil by reversing the normal air flow. Air is pulled in through the
front and discharges over the engine. Compressed air or water may be used as a cleaning agent.
It may be necessary to use warm water mixed with any good commercial dishwasher detergent. If a detergent is
used, rinse coil with fresh water.
5.15 ADJUSTING THE COMPRESSOR PRESSURE REGULATING VALVE (CPR)
The CPR valve is factory preset and should not need adjustment. Use the following instructions if it becomes nec-
essary to adjust the valve for any reason.
NOTE
When adjusting the CPR valve, the unit must be running in the high-speed heat or defrost. Turn Com-
partment 2 OFF, and set Compartment 1 into heat or defrost. This will ensure a full load is against the
unit allowing suction pressure above the proper CPR setting for adjustment.
Figure 5.11 Compressor Pressure Regulating Valve
To adjust the CPR valve, proceed as follows (refer to
a. Install a manifold gauge set.
b. Remove cap from CPR valve.
c. With a 8 mm Allen wrench, loosen the jam nut.
d. Using the 8 mm Allen wrench, adjust the setting screw. To raise the suction pressure turn the setting screw
clockwise; to lower the suction pressure, turn the setting screw counterclockwise. Refer to
for
CPR valve setting.
e. When the setting has been adjusted, tighten the jam nut securely against the setting screw. This will prevent any
movement of the setting screw due to vibrations in the unit. Replace the cap.
Cap
Jam nut
Setting
screw
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