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Replace the relay.
If you have 12 VOLT on terminal 87 and the compressor does not run you
could have a defective Control PCB Assembly or compressor. See testing
Control PCB Assembly. Appendix I.
E. Pressure Switch Testing: You must remove the top section of the ParkSmart
unit to access the switch.
The brazed switch (see photo page 7) is not removable. This switch is
normally closed. When the unit is off for a few minutes, unplug the 32 pin
connector on the PCB assembly and check across terminals D2 and D5, you
should always have continuity. If you do not, you may have a broken wire, bad
connection, hi pressure situation or defective switch. If the pressure, harness
and connections are ok, the unit will have to be replaced. Call Freightliner
Dealer
F. Check continuity across fuse body (fuse does not look blown)
NEVER INSTALL FUSE F6. THIS IS FOR PROGRAMMING ONLY AND IF
INSTALLED IT WILL DISABLE THE PARKSMART UNIT!
Remove fuse from fuse holder. Using a meter, check for continuity across the
fuse. You can check for voltage across the fuse using a dc volt meter.
G. Evaporator Sensor/Freeze Switch Testing: Location: Top of unit, behind the
evap coil, just inside the Cabinet base.
IF THE SENSOR OR CIRCUIT HAS A SHORT OR OPEN, the fault code
will be seen on J1939. IF THE SENSOR IS DEFECTIVE THE
COMPRESSOR WILL NOT OPERATE!
The freeze switch is a temperature sensor. To verify the condition you will need
a Volt/OHM meter.
If a freeze condition occurs, the unit will stop the compressor. If the freeze
condition leaves, the compressor will restart and the ParkSmart unit will
continue to run.
See chart page 19 for sensor test data.
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