True GDIM-26 Installation Manual page 15

True Food Service Equipment, Inc.
True Food Service Equipment, Inc.
4. If all operating conditions are nor-
mal, the voltage supply at the compres-
sor terminals balanced and within lim-
its, the compressor crankcase tempera-
ture within normal limits, and the
amperage drawn within the specified
range, the motor protector may be
defective, and should be replaced.
If the operating conditions are normal
and the compressor is running exces-
sively hot for no observable reason, or
if the amperage drawn is above the nor-
mal range and sufficient to repeatedly
trip the protector, the compressor has
internal damage and should be
replaced.
IF THE COMPRESSOR RUNS
BUT WILL NOT REFRIGERATE
1. Check the refrigerant charge.
Check the evaporator surface to deter-
mine if it is evenly cold throughout, or
if partially starved. A lack of charge
may be indicated by light, fluffy frost at
the evaporator inlet. Add refrigerant if
necessary.
2. Check the compressor suction pres-
sure. An abnormally low pressure may
indicate a loss of refrigerant charge, a
malfunctioning capillary tube, a lack of
evaporator capacity possibly due to
icing or low air flow, or a restriction in
the system.
Often a restriction in a drier or strainer
can be identified by frost or a decrease
in temperature across the restriction due
to the pressure drop in the line. This
will be true only if liquid refrigerant is
in the line at the restricted point, since
any temperature change due to restric-
tion would be caused by the flashing of
liquid into vapor as the pressure
changes.
Any abnormal restriction in the system
must be corrected.
13
13
MAINTENANCE, CARE & CLEANING
MAINTENANCE, CARE & CLEANING
3. Check the compressor discharge
pressure. An abnormally high dis-
charge pressure can cause a loss of
capacity, and can be caused by a dirty
condenser, a malfunctioning condenser
fan, or air in the system.
4. If the suction pressure is high, and
the evaporator and condenser are func-
tioning normally, check the compressor
amperage draw. An amperage draw
near or above the nameplate rating indi-
cates normal compressor or unit may
have damaged valves.
An amperage draw considerably below
the nameplate rating may indicate a
broken suction reed or broken
connecting rod in the compressor.
DIAGNOSIS AND REPLACE-
MENT OF FREEZER CABINET
COMPONENTS
1. Defrost Time Clock
A. Check timer motor to be sure
it runs.
B. Check contacts on the defrost
timer.
C. Check solenoid windings for
continuity to ensure contact
switching.
D. Check to be sure defrost
actuator pins are in proper
position.
E. Check all wires in the timer for
tightness to terminals and
broken wires.
2. Defrost Control On The
Evaporator Drain Pan
A. If the defrost time is always 35
minutes (or whatever duration the
elapsed time adjustment is set at) and
the fan motors do not delay after a
defrost cycle and it has been deter-
mined that the solenoid in the defrost
clock is functioning, change the defrost
control in the evaporator compartment
in the top of the freezer. This control is
attached to the evaporator drain pan.
............ www.truemfg.com ............
............ www.truemfg.com ............
3. Coil Defrost Heater
A. Lower the evaporator cover.
Disconnect the coil heater by removing
the wire nuts at the point where the
heater joins the electrical circuit of the
freezer in the evaporator compartment.
Check heater for continuity with an
ohmmeter. If the heater is defective,
cut the bale wires holding the heater to
the coil and remove the heater. Replace
with a new heater using bale wires pro-
vided.
4. Drain Tube Heater
A. Lower the evaporator cover.
Disconnect the drain tube heater by
removing the wire nuts at the point
where the heater joins the electrical
circuit of the freezer in the evaporator
compartment. Check the drain tube
heater with an ohmmeter.
B. If the drain tube heater is
defective, disconnect the drain tube
from the rigid plastic drain, bend the
tabs that hold the evaporator drain pan
to the evaporator cover and raise the
drain pan so that the flexible heater is
visible, pull heater out of the plastic
drain tube and replace. Connect heater
to the electrical circuit in the evaporator
compartment.
5. Cabinet Temperature
Control
A. Remove the two screws on the
right side of the evaporator housing that
holds the control mounting plate.
Reach behind the evaporator housing
on the control side of the cabinet and
pull the control bulb out of the recepta-
cle in the roof of the cabinet.
Disconnect the wires from the control.
Check control for continuity, replace if
defective.
13
13