Saab 900 Service Manual page 47

Heating and ventilation system, air conditioning system 854-35
A, continuation from page 854-34
Check whether the flow of refrigerant is restricted.
1. Check whether the receiver shell is cold and frosty. If so, dis-
charge the system and replace the receiver shell.
2. If not, check whether the expansion valve is blocked as follows:
Discharge the system. Remove the expansion valve and check
whether the valve filter is blocked. Clean and check if the
valve is clear by blowing through it. If not, replace the expan-
sion valve..
.If
the expansion valve is correct replace the re-
ceiver shell.
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B continuation from page 854-34 ,
Is the compressor switch working in
No
on/off cycles?
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Yes
Replace the anti-frost thermostat. The compressor is continually connected The compressor is continually
disconnected.
Disconnect the voltage supply to the
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compressor switch.
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Check the electric circuit through
the anti-frost thermostat and mag-
Compressor disconnected Compressor still connected
netic clutch.
Check the pressure on the high-
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pressure side. Idling speed 1500 r.p.m. Faulty compressor switch.
Low pressure on the high-pressure side
High pressure on the high-pressure side
«142 psi, 10 kp/cm 2 )
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(>242 psi, 17 kp/cm 2 )
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1. Check that the compressor's mag- 1. Check that the radiator fans are
n~tic clutch rotates freely. If so, working.
measure the voltage to the magnetic 2. Check that there is a good contact to
clutch (must not fall below 11 V). If
the sensitive body of the expansion
voltage is correct, replace magnetic valve.
clutch. 3. Check that the system is not over-full
2. If magnetic clutch is correct, replace
with refrigerant as follows: Position
compressor.
a thermometer in the middle panel
vent.
Idling speed 1500 r.p.m. Slowly re-
lease the refrigerant from the system
and note the temperature at the air
vent and the pressure on the high-
pressure side.
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The temperature at the air vent drops The temperature at the air vent
when the pressure on the high-pressure increases when the pressure on the
side drops.
high-pressure side drops.
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Check the system for leaks. Seal the Defective expansion valve.
leaks, discharge the system and recharge.
Replace.
,. Saab900