Welbilt FB081TF, Service Manual

Page: 76 / 96

76 Part Number REV00 04/08/2020
Component Check Procedures Section 7
COMPRESSOR DRAWING LOCKED ROTOR
To determine if the compressor is seized, check the amp
draw while the compressor is trying to start.
The two likely causes of this are a defective starting
component and a mechanically seized compressor.
To determine which you have:
Install high and low side gauges.
Try to start the compressor.
Watch the pressures closely.
If the pressures do not move, the compressor is seized.
Replace the compressor.
If the pressures move, the compressor is turning slowly and
is not seized. Check the capacitors and relay.
COMPRESSOR DRAWING HIGH AMPS
The continuous amperage draw on start-up should not be
near the maximum fuse size indicated on the serial tag.
DIAGNOSING CAPACITORS
If the compressor attempts to start, or hums and trips the
overload protector, check the starting components before
replacing the compressor.
Visual evidence of capacitor failure can include a bulged
terminal end or a ruptured membrane. Do not assume a
capacitor is good if no visual evidence is present.
Use a capacitor tester when checking a suspect capacitor.
Clip the bleed resistor off the capacitor terminals before
testing.
If the compressor hums and will not start but the windings
are OK. Replace the start capacitor.
A good test is to install a known good substitute capacitor.
FILTER-DRIERS
Location
Ice maker: Behind the compressor & cabinet: between
compressor and condenser coil.
Function
To remove moister and particulates from the refrigerant.
This will prevent premature failure of the compressor and
blocking of restrictor devices.
Specification
The size of the filter-drier is important due to a critical
refrigerant charge. Using an improperly sized filter- drier
will cause the refrigeration system to be improperly
charged with refrigerant.
Driers are covered as a warranty part. The drier must be
replaced any time the system is opened for repairs. Refer
to the parts manual for the recommended OEM field
replacement drier.
Check Procedure
The drier should not alter the temperature of the
refrigerant. Compare the temperature of the copper pipe
either side of the filter/drier, they should be the same.
If there is a temperature drop that indicates a partial
blockage of the filter/drier and it should be replaced.
4.