Fault Code 4

Fault Code 4:

1. Manually increase blower speed from 1 to 8 bar blower segments. If blower goes to high speed, proceed to step 2. If blower does not go to high speed, proceed as follows:
a. Remove ATC control and disconnect electrical connector from the control.
b. Measure resistance between connector pins 2 and 12. If resistance measures 2600-2800 ohms, replace ATC control. If resistance is not as specified, proceed to step c.
c. Check for continuity between pin 13 of PVM and pin 2 of ATC control. If continuity exists, replace vacuum module. If continuity does not exist, repair wiring and recheck system.
2. Cycle A/C button on and off while not in the Defrost mode and note compressor operation.
- If compressor does cycle with switch operation, replace ATC control.
- If compressor does not cycle with switch operation, proceed as follows:
a. Disconnect low pressure cutout switch or electronic cycling switch and run diagnostics. If code 4 is not displayed, locate and repair fault between A/C switch and engine controller. If code 4 is still displayed, proceed to step b.
b. Check for continuity between ATC control pin 13 and and cycling switch. If continuity exists, replace ATC control. If continuity does not exist, repair circuit and recheck system.