Heating and Air Conditioning
N:10:05
UNUSUAL NOISE
Compressor Mounting Components
Check for:
• Loose belt, torque to 80-90 ft. lbs.
• Broken bracket
and/or
compressor mounting
ear, replace broken component.
• Missing, broken or loose bolts at compressor
and engine fixing points.
• Flush fit at all points and replace any bracket
component not fitting properly. Torque bolts to
engine using manufacturer's specifications.
• Loose or wobbling crankshaft pulley, and for
center bolt torque and "bottoming". Repair to
bracket manufacturer's specifications.
• Rough idler pulley bearing. Replace if necessary.
VALVE PLATE TEST
Valve plate failures (suction or discharge valve or
gasket) may be determined with the compressor
installed on the car.
Discharge or Suction Valve Breakage — When
compressor is operated at idling speed,
compressor makes a "clacking" sound.
Head Gasket Breakage — At idling speed,
discharge pressure does not increase to normal
condition and suction pressure is
high.
Checking Method of Discharge Valve and
Head Gasket by Pressure Balancing Test —
Engine Component Noise
Check for noise in:
• Alternator bearing.
• Air pump (if any).
• Water pump bearing.
• Engine valves.
• Timing mechanism.
• Loose engine mounting bolts.
~J
Refrigerant Charge
• A 0-5 psig or lower suction pressure due to a
low refrigerant charge can cause unusual noise.
Restore refrigerant to proper level.
• Re-test by applying heat to evaporator for higher
suction pressure.
Clutch Bearing
See Clutch Test.
Oil Level
Insufficient oil can cause unusual noise. See Oil
Check — Procedure "B".
Valve Noise
Check for a broken or distorted reed valve or
broken gasket.
Step 1 — Connect manifold gauge set to suction
and discharge service ports.
Step 2 — Run compressor for 5 minutes at idling
speed and stop.
Step 3 — Measure elapsed time that discharge
pressure is balanced to suction pressure. If less
than 2 minutes, it is determined that discharge
valve or head gasket is broken.
CLUTCH SERVICE
General
All clutch service operations should be performed
on the bench. Service operations described below
apply to all clutches:
• The clutches for all models include a visible
counterweight on the front plate to improve
dynamic balance. The counterweight clutch fits
all models which have a controlled compressor
shaft keyway so that the counterweight offsets
the cam angle. The clutch without the
counterweight fits 1979 and prior models.
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