Buick LeSabre 1965 Service Manual page 844

INSUFFICIENT COOLING
| Check Air Flow |
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Normal Air Flow
Inspect system for visual defects
Run functional test
Low Air Flow
Check Blower Operation
Discharge Air - Normal Temp.
Check for air leaks thru dash,
car body, windows, or from
hearer or Ventilators.
Discharge Air - High Temp.
Check sight glass for foaming.
Compare evaporator pressure to
that on functional test chart.
Foaming
System is probably low on refrigerant.
Check for leaks, repair and add re-
frigerant. If foaming still occurs
check for restriction in refrigerant
system between condenser and sight
glass.
Ice Blocking Evaporator
Run functional test. If
evaporator pressure is low
ice may form on evaporator
and reduce air flow .Adjust
suction throttle valve.
Blower Operating Normal
Check for following:
Flexible hoses loose, re-
striction or leakage in air
ducts, clogged evaporator
Blower Not Operating
Check for following:
Fuse blown, blower switch
defective, wire broken or
loose connection, blower
motor defective.
Evaporator Pressure Normal
Compare head pressures to
that on functional test chart.
Heod Pressure High
Check for following:
Condenser air flow
low, air in system,
excess refrigerant in
system, restriction in
condenser.
Heod Pressure Normal
Air by-passing evaporator,
Check for proper seal.
Evaporator Pressure Low
Ice may be forming on evaporator. Re-adjust suction throttle valve
to proper control pressure. If cooling remains low after pressure is
normal, follow diagnosis under "Evaporator Pressure Normal". If
stv does not respond to adjustment, hoses to and from valve may
be restricted, valve or compressor may be defective.
Evaporator Pressure High
Re-adjust suction throttle
valve to normal evaporator
pressure. If unable to re-
adjust to normal try to re-
adjust to higher evaporator
pressure.
Responds to Adjustment
Head Pressure Low
Restriction in flow of
refrigerant to evapor-
ator expansion valve
plugged or defective.
Normal Evaporator Pressure
If cooling remains low after pressure is
normal, follow diagnosis under
"Evaporator Pressure Normal"
Evaporator Pressure High
Check installation of expansion valve
capillary bulb. If bulb is tight and
pressure is high, remove bulb from pipe.
No Response To Adjustment
Suction throttle valve is
defective. Repair valve.
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Evaporator Pressure Increases
Indicates compressor capacity to
be sub-standard. Check for clutch
slippage, belt slippage and listen
for unusual noises. Repair clutch,
compressor or replace belts.
Evaporator Pressure Remains The Same
Valve is stuck open and too much
refrigerant is entering evaporator.
Replace thermostatic expansion
valve.
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Figure 11-156—Air Conditioner Trouble Diagnosis Chart