Dodge RAM 1500 1998 Owner's Manual page 2491

24 - 4 HEATING & AIR CONDITIONING
HEATING & AIR CONDITIONING (Continued)
Ambient Air
Temperature
Air Temperature at
Center Panel Outlet
Compressor Inlet
Pressure at Service
Port (low Side)
Compressor
Discharge Pressure at
Service Port (High
Side)
(9) Compare the compressor discharge pressure to
the Performance Temperature and Pressure chart. If
Condition
Constant compressor
engagement and warm air
from passenger vents.
Equal pressures, but the
compressor clutch does not
engage.
PERFORMANCE TEMPERATURE AND PRESSURE
21° C
(70° F) (80° F)
7° C
(45° F) (45° F)
138 to 207 kPa 172 to 241 kPa
(20 to 30 psi) (25 to 35 psi)
1034 to 1724 1379 to 2068
kPa
(150 to 250 (200 to 300
psi)
PRESSURE DIAGNOSIS
Possible Causes
1. Low refrigerant system
charge.
1. No refrigerant in the
refrigerant system.
2. Faulty fuse.
3. Faulty A/C compressor
clutch coil.
4. Faulty A/C compressor
clutch relay.
5. Improperly installed or
faulty Evaporator
Temperature Sensor.
6. Faulty A/C pressure
transducer.
7. Faulty Powertrain Control
Module (PCM).
27° C 32° C
(90° F)
7° C 13° C
(55° F)
207 to 276
kPa
(30 to 40 psi)
1724 to 2413
kPa kPa
(250 to 350
psi) psi)
the compressor discharge pressure is high, see the
Pressure Diagnosis chart.
1. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
1. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
2. Check the fuses in the Power Distribution
Center and the junction block. Repair the shorted
circuit or component and replace the fuses, if
required.
3. See A/C Compressor Clutch Coil in this group.
Test the compressor clutch coil and replace, if
required.
4. See A/C Compressor Clutch Relay in this
group. Test the compressor clutch relay and relay
circuits. Repair the circuits or replace the relay, if
required.
5. See Evaporator Temperature Sensor in this
group. Reinstall or replace the sensor as
required.
6. See A/C pressure transducer in this group.
Test the switch and replace, if required.
7. (Refer to Appropriate Diagnostic Information).
Test the PCM and replace, if required.
38° C 43° C
(100° F) (110° F)
13° C 18° C
(55° F) (64° F)
241 to 310
276 to 345 kPa
kPa
(40 to 50 psi)
(35 to 45 psi)
1999 to 2689
2413 to 2965
kPa
kPa
(290 to 390
(350 to 430 psi)
psi)
Correction
DR