Circuit Operation

Fig 2 Scroll TR-105 Compressor:

The air conditioning system uses a Scroll TR-105 fixed displacement compressor on all models. A label identifying the use of R-134a refrigerant is located on the compressor. The purpose of the compressor is to compress the low-pressure refrigerant vapor from the evaporator into a high-pressure, high temperature vapor.

The compressor cannot be repaired and, if faulty or damaged, it must be replaced.

CIRCUIT OPERATION
When the operator selects air conditioning or defrost operation the Powertrain Control Module receives the A/C select signal on circuit C90. If the A/C low pressure switch, electronic cycling switch, and A/C high pressure switch are closed, the PCM also receives the A/C request on circuit C20. Circuit C20 from the high pressure switch connects to cavity C22 of the PCM. Circuit C90 from the A/C-heater control switch connects to cavity C23 of the PCM and to the low pressure switch.
- Circuit C90 connects the A/C-heater control switch to the A/C low pressure switch.
- Circuit C2 connects the A/C low pressure switch to the electronic cycling switch.
- Circuit C22 connects the electronic cycling switch to the A/C high pressure switch. Circuit F18 from fuse 19 in the fuse block supplies voltage to the electronic cycling switch when the ignition switch is in the START or RUN position.
- When the A/C-heater control switch is in an A/C position or the defrost position, it connects circuit C90 to ground circuit Z1. The PCM senses the ground, which is the A/C select signal, on circuit C90.

After receiving the A/C request signal, the PCM provides ground for the coil side of the A/C compressor clutch relay on circuit C13. Circuit C13 connects to cavity C1 of the PCM.

When the PCM grounds the relay, the relay contacts close and connect circuit A17 to circuit C3. Circuit C3 supplies voltage to the A/C compressor clutch. Ground for the compressor clutch is provided on circuit Z1.

The A/C compressor clutch connector has a built-in diode. The diode controls the induced voltage that results from the collapsing magnetic field clutch disengagement. The diode provides a current path to ground to protect other components and systems.