DTC 4 - Blend/Passenger Actuator Did Not Reach Hot Stop

DIAGNOSTIC TROUBLE CODE 4 - BLEND/PASSENGER ACTUATOR DID NOT REACH "HOT" STOP
When the HVAC Control Module calibrates the Blend/Passenger Door Actuator, it moves the actuator A toward the HOT position and then toward the Cool position. In the HOT position, circuit C36 of the 21 pin connector should have a value of approximately 3.8 to 4.1 volts. When the actuator does not reach the HOT position, DTC 4 sets

Detection
When the voltage at C36 is less than 3.0 volts, the DRB III will display the DTC.

Possible Causes
- Blend/Passenger Door reaches the HOT position and does not respond to changes in control panel settings.
- Blend/Passenger Feedback Signal circuit is SHORTED to ground.
- Blend/Passenger Feedback Signal circuit is OPEN.
- Blend/Passenger Actuator is stuck. Blend/Passenger Door is stuck.
- Blend/Passenger Door Actuator Driver circuit is OPEN.
- Blend/Passenger Door Actuator Driver circuit is SHORTED to Actuator Common. Cold air is supplied with DTC 4.
- Blend/Passenger Door Actuator Driver circuit is SHORTED to ground. Diagnostics begin momentarily and then STOP with NO LED's until the short is removed, and then both WIPE and INTERMITTENT LED's flash simultaneously.
- Blend/Passenger Door Actuator gear is not properly connected.
- Battery voltage is less than 10.0 volts.
- 5 volts supply circuit is OPEN may set multiple DTC's 2, 4, and 8, depending on where the OPEN is located.
- Sensor ground circuit OPEN may set multiple DTC's 1, 4, 5, and 8, depending on where the OPEN is located.

If there is HOT air flow (passenger side on Zone control), even though the DTC indicates that the actuator cannot reach Hot position, there is a short to ground or an open in the Blend/Passenger Feedback Signal circuit (the door is moved to the Hot position, attempting to increases the feedback voltage.

If the Blend/Passenger actuator fails in the Mid position, both DTC's 3 and 4 will be set.

If the Blend/Passenger Door/Actuator fails in the Cool position and is blowing cool air, DTC 4 is set.

Test Procedures
1. Check if the correct HVAC control module was used.
Disconnect the Actuator connector.
2. Using a voltmeter, measure between pins 1 and 5. If the voltage is not 12 volts ± 1 volt, check the actuator driver circuits wiring for a short or open circuit. Measure the voltage between pins 2 and 4. If the voltage is less than 4 volts, check the 5 volt supply circuit. Measure the voltage between pins 3 and 4. If the voltage is less than 4.5 volts, check the actuator feedback circuit.
3. Remove actuator, and check if the gear pins are in the correct track on cam or if they are binding. If OK, go to Step 4. If not OK, repair as necessary.
4. Check for binding door, if door is binding repair as necessary. If gears and door are OK, replace actuator.
5. Once repairs are completed repeat the Calibration Diagnostic and Cooldown test. Repeating the test is necessary to clear the fault codes.