74-Ac Request Output Signal Too Low (MTC): Notes

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: A/C Switch Sense Circuit Diagram

Courtesy of DAIMLERCHRYSLER CORP.

For the Manual Temperature Control (MTC) circuit diagram (Refer to HEATING & AIR CONDITIONING - SCHEMATICS AND DIAGRAMS) .

For a complete wiring diagram refer to SYSTEM WIRING DIAGRAMS .

When Monitored:
With the ignition on.
Set Condition:
If the A/C Heater Control detects voltage below 1.51 volts on the (C221) A/C Switch Sense circuit.

Possible Causes
(C221) A/C SWITCH SENSE CIRCUIT SHORTED TO GROUND
(C221) A/C SWITCH SENSE CIRCUIT OPEN
INSTRUMENT CLUSTER (CCN)
A/C HEATER CONTROL

NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. Refer to HVAC System Test (MTC) for stored DTC test procedures.