Chrysler neon 1997 Service Manual page 1648

PL
DIAGNOSIS AND TESTING (Continued)
VACUUM CONTROL SYSTEM
Use an adjustable vacuum test set (Special Tool
C-3707) and a suitable vacuum pump to test the
heater-A/C vacuum control system. With a finger
placed over the end of the vacuum test hose probe
(Fig. 16), adjust the bleed valve on the test set gauge
to obtain a vacuum of exactly 27 kPa (8 in. Hg.).
Release and block the end of the probe several times
to verify that the vacuum reading returns to the
exact 27 kPa (8 in. Hg.) setting. Otherwise, a false
reading will be obtained during testing.
ONE-WAY CHECK VALVE
(1) Disconnect the heater-A/C vacuum supply
(Black) tube in the engine compartment. This tube
passes through an opening in the dash panel.
(2) Remove the one-way vacuum check valve. The
valve is located on the (Black) vacuum supply hose at
the brake power booster.
(3) Connect the test set vacuum supply hose to the
heater side of the valve. When connected to this side
of the check valve, no vacuum should pass and the
test set gauge should return to the 27 kPa (8 in. Hg.)
setting. If OK, go to step Step 4. If not OK, replace
the faulty valve.
CONDITION
NO FORCED AIR IN HEAT
POSITION
NO FORCED AIR IN PANEL
POSITION
NO FORCED AIR IN DEFROST
POSITION
engine vacuum side of the valve. When connected to
this side of the check valve, vacuum should flow
through the valve without restriction. If not OK,
replace the faulty valve.
POSSIBLE CAUSES
1. Vacuum line pinched or leaking.
2. Faulty heat defroster or mode
door.
3. Faulty selector switch.
4. Vacuum check valve.
1. Vacuum line pinched or leaking.
2. Faulty mode door.
3. Faulty selector switch.
4. Vacuum check valve.
1. Vacuum line pinched or leaking.
2. Faulty heat defroster or mode
door.
3. Faulty selector switch.
4. Vacuum check valve.
Heater-A/C Vacuum System Diagnosis
HEATING AND AIR CONDITIONING
Fig. 16 Adjust Vacuum Test Bleed Valve
(4) Connect the test set vacuum supply hose to the
CORRECTION
1. Locate and repair vacuum leak or
pinched line.
2. Test actuators and door
operation. Repair as necessary.
3. Test selector switch and replace if
necessary.
4. Test check valve and replace if
necessary.
1. Locate and repair vacuum leak or
pinched line.
2. Test actuator and door operation.
Repair as necessary.
3. Test selector switch and replace if
necessary.
4. Test check valve and replace if
necessary.
1. Locate and repair vacuum leak or
pinched line.
2. Test actuators and door
operation. Repair as necessary.
3. Test selector switch and replace if
necessary.
4. Test check valve and replace if
necessary.
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