The voltage after the A/C relay is used to supply power to the A/C compressor magnetic clutch. When the A/C switch is turned on, applies the battery voltage to the ECM. When A/C ON signal is input, A/C power relay coil is energized to turn on the relay switch, which activates the A/C compressor magnetic clutch by the ECM. In case of the A/C relay failure, the engine symptoms will be deactivated A/C compressor magnetic clutch.
If the A/C relay circuit is short to battery line or open during two driving cycles, this code will be set.
DTC NO.
Detecting Condition
Possible Cause
C 018
C 019
? C 018
Short circuit to battery line
? C 019
Open circuit :
? Short circuit to ground
? Wire broken
? Too high temperature in power stage
? Engine Condition : IG ON
? Fuel Limit : NO
? Fuel Cut : NO
? EGR OFF : NO
? MIL : NO
? Open or short in circuit
? Relay
? ECM