WD Catalog 2018

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10-2
Chapter 10 – Component Repair or Replacement
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Machine crimped fittings are preferred over those fittings which use hose
clamps. Properly crimped ferrules make stronger connections than hose
clamps, and are recommended by the manufacturers of refrigerant hose.
Use crimped fittings on hose brands such as Goodyear Galaxy. Steel
fittings are preferred over aluminum in heavy duty applications. Use
reusable fittings on the nylon-lined hose brands such as Aeroquip FC 202.
2. Lines
Always use two wrenches when disconnecting or connecting AC fittings
attached to metal lines. You could be working with copper and aluminum
tubing which can kink or break easily. Tube O-ring type fittings require
only 18 foot pounds of torque for correct sealing. When there are grom-
mets or clamps used to prevent line vibration, be sure these are in place
and secured.
3. Expansion Valves
When removing the expansion valve from the system, remove the insula-
tion, clean the area, and disconnect the line from the receiver-drier.
Detach the capillary (bulb) and external equalizer tube (if present) from
their mounting locations. Remove the expansion valve from the evapora-
tor inlet. Expansion valve service is limited to cleaning or replacing the
filter screen. If this is not the problem, replace the valve. If there is any
debris in a block-type valve, replace it. Secure the capillary and equalizer,
if used, and replace any insulating material.
4. Expansion Tubes
A clogged or defective expansion tube must be replaced. There are special
tools available to remove and replace tubes at their location. If you don’t
have one, you may be able to use a pair of needle-nose pliers. Put a little
refrigerant oil in the evaporator inlet to lubricate the expansion tube for
easier removal. Discard the old tube. Lubricate the new tube and O-ring
and insert until it seats against the dimples in the evaporator inlet.
5. Receiver-Drier & Accumulator
The receiver-drier and accumulator can not be serviced or repaired. They
should be replaced whenever the AC system is opened for any service. If
the receiver-drier or accumulator has a pressure switch to control the
clutch, it should be removed and installed on the new unit.
6. Compressor & Clutch
Problems with the clutch assembly can be due to low voltage, electrical
failure in the coil, the lead wire or a bad pulley bearing. Check first to see
that electrical power is reaching the clutch. The lead wire and bearing can
be replaced and the clutch assembly reinstalled. If the coil fails, it must be
replaced. If the clutch shows obvious signs of excessive heat, replace the
complete assembly. The compressor can fail due to shaft seal leaks,
defective valve plates, bad bearings, or problems associated with high
pressure, heat or lack of lubrication.