Part 2 of 2

A/C Compressor Clutch Circuit Diagram:

CIRCUIT DESCRIPTON
The A/C clutch relay gets battery power when the ignition is turned and energized when the PCM completes the circuit to ground. When energized, the relay turns the A/C compressor clutch "ON", engaging the compressor. The A/C pressure sensor signal is used to determine high and low pressure in the system and for cooling fan control. When the A/C is turned on, the PCM delays the clutch engagement of the A/C compressor for a fraction iof a second, allowing the IAC valve time to increase air flow and compensate for the added load. The PCM also turns the relay "OFF", disengaging the A/C clutch, under the following conditions:

^ Wide open throttle
^ High power steering pressure is present at idle
^ When the engine is overheating
^ When the A/C system pressures are not within a specified range.
^ Engine speed excedes 6,000 rpm.
^ Code 66 present

TEST DESCRIPTION

Chart C-10, A/C Compressor Clutch Control Circuit Diagnosis (2 Of 2):

Numbers below refer to circled numbers on diagnostic chart.

1. Determines is the pressure transducer signal indicates pressures out of range.
2. With the engine stopped and field service mode activated, the PCM should be completing relay circuit 459.

DIAGNOSTIC AIDS
If the complaint is insufficient cooling, the problem may be an inoperative engine cooling fan. Chart C-12 Coolant Fan Control Circuit If cooling fans operate properly, problem may be A/C pressures outside of range, or faulty pressure transducer indicating pressure out of range (43 - 428 psi). Monitor A/C pressure with "SCAN" tool and compare to actual readings with A/C manifold/gauges. "SCAN" readings should be within 20 psi of actual pressure. If not see Code 66 diagnostic chart, or replace pressure transducer. If actual pressures are out-of-range, refer to HEATING AND AIR CONDITIONING.