Saab 900 Service Manual page 45

Heating and ventilation system, air conditioning system 854-33
Symptom
tID
E
tID
C
Q) I
+-'
c
Vl
tID
0 >,
C
0 0
Vl
0
0 U
C
U
U
0
Q) '.;:J
Q)
U
~
Vl
....,
0
....,
0
Z
::i
UJ
Z
Possible cause
Check/remedy
System faults:
X Anti-frost thermostat fails to make Check that the thermostat is fUlly inserted in the
circuit to fitted, compressor
evaporator. If correctly change the thermostat
X Expansion valve stuck Change the expansion valve
open
X
Leak in system
Recharge the system and test for and repair any leaks
X Blockage in hose or component Check the flow through each component
X System starved of refrigerant Recharge the system
X Airfilter clogged on inletside Change the filter
X
X
Insufficient refrigerant in the system Dra in the system and recharge
(whistling noise from expansion valve on
evaporator - bubbles visible in the sight glas)
X Expansion valve capillary tube damaged Change the expansion valve
(Tube empty of medium)
X Receiver clogged Change the rece iver
X X
Moisture in the system. Cooling good
Drain the system, change the receiver
initially (for a few minutes) and then and recharge with refrigerant
deteriorating. Alternatively, deterioration
at high ambient temperature
X
Air in the system (Bubbles visible in Drain the system, change the receiver and
sight glass) refrigerant
X Frosting on air side of evaporator Make sure that the capillary tube forthe anti-frost
thermostat- is corre'ctly locate'd betw,eenthe:
fins on the evaporator. If so, change the thermostat
X Play in anti-frost thermostat Check the thermostat and change if necessary
X
Coil on expansion valve capillary tube Check the contact and insulation
not making good contact with evaporator
outlet pipe or poorly insulated from air
temperature
X Interval between cut-in and cut-out Change the thermostat
temperature of anti-frost thermostat too
great
X System flooded: :Causes rumbling noise or Drain the system and recharge.
vibration in high-pressure line, gurgling noise
in compressor, excessive compressor and
suction pressure, hissing noise in expansion
valve and bubbles or vapour in sight glass.
Ifthe compressorvalves have been damaged
by an excess charge of refrigerant in the sys-
tem, the compressor pressure will be too low
X Excessive moisture in the system Drain the system. Change the receiver and recharge
can cause noise in the expansion valve the system with refrigerant
Saab 900