DTC 49

CIRCUIT DESCRIPTION

The Electronic Climate Control (ECC) Head controls the A/C clutch via the A/C cutout relay. The ECC Head uses data obtained from the ECM via the Assembly Line Data Link (ALDL) line, such as coolant temperature, rpm, vehicle speed, etc. In addition to its own inputs to determine when to cycle the compressor, if commanded on by the ECC Head, the compressor clutch will engage only if the low freon pressure switch IS closed and if engine temperature is within normal operation range.

Code 48 will set if the low freon pressure switch opens and compressor will he forced off and the ECC will default to ECON until the next ignition cycle. Code 49 will set if the ECC receives a hot engine signal from the ECM, in which case the compressor will be turned off and ECC will revert to ECON.

TEST DESCRIPTION

Numbers below refer to circles numbers on the diagnostic chart.

1. This test checks to see if the fault is due to the circuitry or the low freon pressure switch or refrigerant system.

2. This test checks to see if the fault is an open in CKT 730 or faulty ECC Head.

3. This Lest checks to see if the fault is a bad low freon pressure switch or a refrigerant system problem.