HEATER, AIR CONDITIONER AND VENTILATION–On-vehicle Service55-21
REFRIGERANT LEAK REPAIR
LOST CHARGE
If the system has lost all charge due to a leak:
1. Evacuate the system. (See procedure.)
2. Charge the system with approximately one
pound of refrigerant.
3. Check for leaks.
4. Discharge the system.
5. Repair leaks.
6. Replace receiver drier.
Caution
Replacement filter-drier units must be
sealed while in storage. The drier used in
these units will saturate water quickly upon
exposure to the atmosphere. When
installing a drier, have all tools and supplies
ready for quick reassembly to avoid keeping
the system open any longer than necessary.
7. Evacuate and charge system.
LOW CHARGE
If the system has not lost all of its refrigerant charge;
locate and repair all leaks. If it is necessary to
increase the system pressure to find the leak
(because of an especially low charge) add
refrigerant. If it is possible to repair the leak without
discharging the refrigerant system, use the
procedure for correcting low refrigerant level.HANDLING TUBING AND FITTINGS
Kinks in the refrigerant tubing or sharp bends in
the refrigerant hose lines will greatly reduce the
capacity of the entire system. High pressures are
produced in the system when it is operating.
Extreme care must be exercised to make sure that
all connections are pressure tight. Dirt and moisture
can enter the system when it is opened for repair
or replacement of lines or components. The
following precautions must be observed. The
system must be completely discharged before
opening any fitting of connection in the refrigeration
system. Open fittings with caution even after the
system has been discharged. If any pressure is
noticed as a fitting is loosened, allow trapped
pressure to bleed off very slowly.
Never attempt to rebend formed lines to fit. Use
the correct line for the installation you are servicing.
A good rule for the flexible hose lines is keep the
radius of all bends at least 10 times the diameter
of the hose.
Sharper bends will reduce the flow of refrigerant.
The flexible hose lines should be routed so that
they are at least 80 mm from the exhaust manifold.
It is good practice to inspect all flexible hose lines
at least once a year to make sure they are in good
condition and properly routed.
Unified plumbing connections with O-rings, these
O-rings are not reusable.
COMPRESSOR NOISE
You must first know the conditions when the noise
occurs. These conditions are: weather, vehicle
speed, in gear or neutral, engine temperature or
any other special conditions.
Noises that develop during A/C operation can often
be misleading. For example: what sounds like a
failed front bearing or connecting rod, may be
caused by loose bolts, nuts, mounting brackets,
or a loose clutch assembly. Verify accessory drive
belt tension (power steering or alternator).
Improper accessory drive belt tension can cause
a misleading noise when the compressor is
engaged and little or no noise when the compressor
is disengaged.
Drive belts are speed-sensitive. That is, at different
engine speeds, and depending upon belt tension,
belts can develop unusual noises that are often
mistaken for mechanical problems within the
compressor.ADJUSTMENT
1. Select a quiet area for testing. Duplicate
conditions as much as possible. Switch
compressor on and off several times to clearly
identify compressor noise. To duplicate high
ambient conditions (high head pressure),
restrict air flow through condenser. Install
manifold gauge set to make sure discharge
pressure doesn’t exceed 2,070 kPa.
2. Tighten all compressor mounting bolts, clutch
mounting bolt, and compressor drive belt.
Check to assure clutch coil is tight (no rotation
or wobble).
3. Check refrigerant hoses for rubbing or
interference that can cause unusual noises.
4. Check refrigerant charge. (See “Charging
System”.)
5. Recheck compressor noise as in Step 1.
6. If noise still exists, loosen compressor mounting
bolts and retorque. Repeat Step 1.
7. If noise continues, replace compressor and
repeat Step 1.
