A/C compressor raises pressure to condense the evaporated refrigerant at evaporator in A/C system more easily. Without A/C signal, A/C compressor does not operate but with ON signal, PCU activates A/C compressor relay. With the relay activation, A/C compressor turns on using the power of the engine.
PCM monitors inputted voltage through A/C compressor relay. Checking voltage every 10 sec. under detecting condition, if the voltage lower than the specified value is detected for more than 5 sec., PCM sets P0646.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Detects circuit short to low voltage | ● Poor connection ● Open or short to ground in A/C relay circuit ● Faulty A/C relay ● Faulty PCM |
Enable Conditions | ● After 0.5 sec under conditions below ● No DTC exists ● Engine works ● 11V ≤ Battery voltage ≤ 16V | |
Threshold value | ● Open or short to ground | |
Diagnosis Time | ● Continuous (More than 5 seconds failure for every 10 seconds test) | |
MIL On Condition | ● DTC only (NO MIL ON) |
Coil Resistance | 70Ω ~ 120Ω |
