Dual Function High Pressure Switch/High Pressure Cut-Off Switch Test; Heater Perfomance Test; Maximum Heater Output Diagnosis And Testing - Jeep Cherokee 2000 Service Manual

24 - 16 HEATING AND AIR CONDITIONING
DIAGNOSIS AND TESTING (Continued)
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
Fig. 8 Compressor Clutch Relay
pressor clutch coil wire harness connector. If OK, go
to Step 4. If not OK, repair the open circuit as
required.
(4) The relay coil battery terminal (86) is con-
nected to the fused ignition switch output (run/start)
circuit. There should be battery voltage at the cavity
for relay terminal 86 with the ignition switch in the
On position. If OK, go to Step 5. If not OK, repair the
open circuit to the fuse in the junction block as
required.
(5) The coil ground terminal cavity (85) is switched
to ground through the Powertrain Control Module
(PCM). There should be continuity between this cav-
ity and the A/C compressor clutch relay control cir-
cuit cavity of the PCM wire harness connector C
(gray) at all times. If not OK, repair the open circuit
as required.
Ambient Air Temperature
Minimum Air Temperature at
Floor Outlet
DUAL FUNCTION HIGH PRESSURE SWITCH/
HIGH PRESSURE CUT-OFF SWITCH
Before performing diagnosis of the dual function
high pressure switch, or the high pressure cut-off
switch, verify that the refrigerant system has the cor-
rect refrigerant charge. See Refrigerant System
Charge in the Service Procedures section of this
group for more information.
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the high pressure switch wire harness
connector from the switch on the refrigerant system
fitting.
(3) On the dual function high pressure switch,
check for continuity between terminals C and D. On
the two terminal switch, check for continuity
between both terminals of the high pressure cut-off
switch. There should be continuity. If OK, test and
repair the A/C switch sense circuit as required. If not
OK, replace the faulty switch.
HEATER PERFORMANCE
Before performing the following tests, refer to
Group 7 - Cooling System for the procedures to check
the radiator coolant level, serpentine drive belt ten-
sion, radiator air flow and the radiator fan operation.
Also be certain that the accessory vacuum supply
line is connected at the engine intake manifold.
MAXIMUM HEATER OUTPUT
Engine coolant is delivered to the heater core
through two heater hoses. With the engine idling at
normal operating temperature, set the temperature
control knob in the full hot position, the mode control
switch knob in the floor heat position, and the blower
motor switch knob in the highest speed position.
Using a test thermometer, check the temperature of
the air being discharged at the heater-A/C housing
floor outlets. Compare the test thermometer reading
to the Temperature Reference chart.
Temperature Reference
15.5° C 21.1° C
(60° F) (70° F)
62.2° C 63.8° C
(144° F) (147° F)
26.6° C 32.2° C
(80° F) (90° F)
65.5° C 67.2° C
(150° F) (153° F)
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