Heater-A/C control calibration procedure

If it doesn't cool well does it need a recharge?

AC blows cold, then hot, then cold... - Car Forums and Automotive ...

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A/C now turns on but will blow cold air for 5 seconds then back to hot for the same. ...It seems be be left of the heater box somewhere but it is definately inside. .... on this '98... the things just keeps turning in there, hot, cold, hot and so forth.

on all cars made
(you can read the FSM at any time and see exact way and tests)
1: damper stuck or its actuator bad. ( 3 kinds uses on all cars)
2 ;controls to damper actuator bad.
3: wires between both faulty.

3 types are motor, vacuum servo and cable.
you have 2 of the 3.
the blend is a motor actuator
the recric is vacuum servo
the motor types are very hard to test, read the FSM.

ill post the calibration

quote

Use this procedure to ensure that the A/C-heater control is correctly calibrated to the blend door actuator. If the calibration is not correct, the heating-A/C system may experience a condition where full heating or cooling capabilities cannot be obtained.
Manual calibration of the A/C-heater control should be performed if the blend door actuator is not functioning properly, or if the temperature of the conditioned air is too warm with the temperature control in the full cold position or too cool with the temperature control in the full hot position.
NOTE This calibration procedure can only be started within the first ten seconds after the ignition switch has been turned from the OFF position to the ON position. Make sure that the battery is fully charged prior to beginning the calibration procedure. NOTE The length of the pause made at each end of the temperature control rotation (sweep) is important. 5 seconds) or too long (greater than 1.5 seconds).

1. With the ignition switch in the OFF position, move the temperature control to its middle (12 o'clock) position.
2. Turn the ignition switch to the ON position (do not start the engine).
3. Within 10 seconds of turning the ignition switch from the OFF to the ON position, perform the following rotations (sweeps) of the temperature control.
   • From the 12 o'clock position, rotate the temperature control counter-clockwise to the full cold position. Pause one second.
   • Rotate the control clockwise to the full hot position. Pause one second.
   • Rotate the control counter-clockwise to the full cold position. Pause one second.
   • Rotate the control clockwise to the full hot position. Pause one second.
   • Rotate the control counter-clockwise to the full cold position.

You may find a reset will solve this annoying problem. The problem you have is the GM heater control unit has lost it's calibration, which can happen from time to time. The way to reset it is, start your car and turn your heater off, and shut off the car, pull out the keys. Then with vehicle off, disconnect the battery, (or batteries if it has two). Let sit for 10 minutes, then re-connect battery. Get in and start the engine, DON'T touch anything, let the heater control unit re-calibrate for at least 40 seconds, (by the clock), then try turning on the heater.
Good luck!

on all speeds, is it dead sounding or only no air flow???
wow no symptoms posted only this goose chase deal.

use the scan tool yet? see all DTC errors.
2008 cars can report most cause of lost power etc,
not scanning, invites expensive gue$$ing.!!

HVAC 101: (
gdoes the motor have 12vdc on high? at connector to it>?
on all speed's (now that is a KEY FACT there)

1. defeat air bag first or die , fiddling these parts.
2. do the HVAC calibration yet? per FSM.
3. scan it yet ,if not you will guess wrong. I promise,
4. i have to stop my online page ,is missing the wiring sections.

calibrate damper:
Use this procedure to ensure that the A/C-heater control is correctly calibrated to the blend door actuator. If the calibration is not correct, the heating-A/C system may experience a condition where full heating or cooling capabilities cannot be obtained.

Many steps can not be done with out a real jeep scan system.
sorry, cant.

Check this procedure...Blower Motor Resistor and Controller Replacement


REMOVAL

1. Disconnect and isolate the batten' negative cable.

2. Depress locking tab and unplug the wire harness connector from the blower motor

resistor or controller (power module).

3. Depress locking tab and unplug the resistor or controller connector from the blower

motor.

4. Remove the 2 screws that secure the blower motor resistor or controller to the

heater-AC housing.

5. Remove the blower motor resistor or controller from the heater AC housing.


INSTALLATION

1. Install the blower motor resistor or controller to the heater AC housing. The

housing is indexed to allow (controller power module) mounting in only one

position. Tighten the mounting screws to 2.2 Nm(20 in. Lbs.).

2. Plug in the wire harness connector to the blower motor resistor or controller.

3. Plug in the connector from the blower motor resistor or controller to the blower

motor.

4. Connect the batten' negative cable.




Hope this helps (rerember to rating this and leave a testiomonial).

you have taken the calibration out of sink. you will now have to remove battery power again for about 5 minutes. after this time reconnect the battery. then turn key to on position for 3 minutes but do not touch the heater control or temperature controls. This should allow the heater and ac system to recalibrate. once the 3 minutes is up turn key off and then back on and start truck.. Try your controls again and see what happens. if no change then dealer will have to reprogram the heater control calibration for you.

{: ) Check carefully your settings make sure it's not on defrost or defog positions. If there are no actuator or wiring issues, you can try the following steps:
NOTE: Do not adjust any controls on the HVAC while doing this procedure.
1. Turn off your a/c and the ignition switch.
2. Remove the HVAC/ECAS fuse(10amp) at the underhood fuseblock for 10 seconds.
3. Reinstall the fuse.
4. Start the vehicle. Wait 40 seconds for the HVAC control module to self calibrate.
5. Now you can check the operation of the HVAC controls.
I hope you get lucky. Otherwise, better have it calibrated with a scan tool. If a scan tool is present it can also check for any DTC that might be present, which may render the procedure unsuccessful.

Try this calibration procedure and let us know if you have more questions:

1. Start the vehicle.
   
2. Wait 40 seconds for the HVAC control module to self-calibrate.
3. Verify that no DTCs have set as current DTCs.
4. Clear all DTCs.
5. Place the ignition switch to the OFF position.
6. With the Mode knob in the PANEL position, press and hold the AC button for 5 seconds.
7. Rotate the Mode knob fully counterclockwise.
8. Rotate the Mode knob fully clockwise.
9. Rotate the Mode knob fully counterclockwise.
10. Release the AC button.
11. Wait 40 seconds for the HVAC control module to self-calibrate.
12. Start the vehicle.
13. Verify that no DTCs have set as current DTCs.

probably the blend door not opening fully. Do you hear a clicking under the dash by passenger's feet? If not, try calibrating the system:

1. Place the ignition switch to the OFF position.
   
2. With the Mode knob in the PANEL position, press and hold the AC button for 5 seconds.
3. Rotate the Mode knob fully counterclockwise.
4. Rotate the Mode knob fully clockwise.
5. Rotate the Mode knob fully counterclockwise.
6. Release the AC button.
7. Wait 40 seconds for the HVAC control module to self-calibrate.
8. Start the vehicle.

If this doesn't work, your actuator may have failed. Look under the dash to see if any of the actuators on the heater box are trying to turn when you change the temperature setting. Unfortunately, I cannot find aftermarket parts for your heater, so if the door isn't working you may need to go to the pontiac dealer. Let me know if you have questions.