ON-VEHICLE SERVICE
TSB Revision
HEATER, AIR CONDITIONING AND VENTILATION
55-31
COMPRESSOR NOISE CHECK
M1552008700216
.
You must first know the conditions when the noise occurs.
These conditions are: weather, vehicle speed, in gear or neu-
tral, 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 generator). Improper accessory drive belt
tension can cause a misleading noise when the compressor is
engaged and little or no noise when the compressor is disen-
gaged. 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 (300 psi).
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. (Refer to
P.55-28
.)
5. Recheck compressor noise as in Step 1.
6. If noise still exists, loosen compressor mounting bolts and re
torque. Repeat Step 1.
7. If noise continues, replace compressor and repeat Step 1.