Blend Overcurrent (MTC)

BLEND OVERCURRENT (MTC)





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
When actuator movement is requested.

- Set Condition:
This DTC will set if the A/C Heater Control detects an excessive current draw on any of the door driver circuits while attempting to drive the Passenger Blend Door Actuator. Only one overcurrent DTC can set per ignition cycle.





Diagnostic Test

1. VERIFY DTC IS ACTIVE
Turn the ignition on.
With the scan tool, erase DTCs.
Turn the ignition off, wait 10 seconds, and turn the ignition on.
With the scan tool, read DTCs.
Does the scan tool display this DTC as active?

Yes

- Go To2

No

- The condition that caused this symptom is currently not present. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals. Repair as necessary.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

2. CHECK FOR PROPER PASSENGER BLEND DOOR ACTUATOR OPERATION
Turn the ignition on.
Actuate the Passenger Blend Door Actuator.
Does the Passenger Blend Door Actuator operate normally?

Yes

- Go To4

No

- Go To3

3. CHECK FOR ACTIVE: BLEND DOOR CIRCUIT SHORTED TO GROUND
With the scan tool, erase DTCs.
Turn the ignition off, wait 10 seconds, and turn the ignition on.
Actuate the Passenger Blend Door Actuator.
With the scan tool, read DTCs.
Does the scan tool display active: BLEND DOOR CIRCUIT SHORTED TO GROUND?

Yes

- Follow the diagnostics for BLEND DOOR CIRCUIT SHORTED TO GROUND.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To4

4. CHECK FOR 12 VOLTS TO THE PASSENGER BLEND DOOR ACTUATOR




Turn the ignition off.
Disconnect the Passenger Blend Door Actuator harness connector.
Turn the ignition on.
Actuate the Passenger Blend Door Actuator.
Using a volt meter measure the voltage on the (C33) Passenger Blend Door Driver (A) circuit in the Passenger Blend Door Actuator harness connector.
Does the volt meter read 12 volts?

Yes

- Go To5

No

- Go To6

5. CHECK FOR A BLOCKAGE STALLING THE PASSENGER BLEND DOOR ACTUATOR
Turn the ignition off.
Remove the Passenger Blend Door Actuator from the HVAC housing assembly.
Look for anything on the Passenger Blend Door Actuator and in the HVAC housing that is physically preventing Passenger Blend Door Actuator operation.
Is anything physically preventing Passenger Blend Door Actuator operation?

Yes

- Repair as necessary. Also, check Passenger Blend Door Actuator for proper operation. Reinstall, or replace the Passenger Blend Door Actuator as necessary .

No

- Replace the Passenger Blend Door Actuator.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

6. CHECK FOR CHAFING IN THE (C33) PASSENGER BLEND DOOR DRIVER (A) CIRCUIT
Turn the ignition off.
Check the (C33) Passenger Blend Door Driver (A) circuit for wire chafing.
Is any wire chafing present?

Yes

- Repair the wire chafing on the (C33) Passenger Blend Door Driver (A) circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Replace the A/C Heater Control Head.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.