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Pete
Pete, Car Enthusiast
Category: UK Car
Satisfied Customers: 26339
Experience:  Over 17 years experience diagnosing and repairing automobiles.
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I have 2003 H2 HVAC trouble

Customer Question

I have 2003 H2 HVAC trouble
Submitted: 1 year ago.
Category: UK Car
Expert:  Pete replied 1 year ago.

Hi my name is ***** ***** I will be happy to help with this today.I apologize for any delay.I need a little more info to assist better.

With your scan tool observe the HVAC data list and let me know if the recirculation,left and right air temp actuators read between 5 and 250 counts and with the engine running do they change count at all when switching recirc. off and on or changing air temps?This is the first check so we can continue from here.If you cannot check this let me know.

Thanks Pete

Customer: replied 1 year ago.
Left Mix Door.
Commanded: 0 counts
Actual: 216 countsRight Mix Door.
Commanded: 0 counts
Actual: 5 countsAir inlet Door.
Commanded: 0 counts
Actual: 0 countsNo change at all with control panel.
No change at all with scan tool controlMode door is working well with scan tool and control panel.
Customer: replied 1 year ago.
I have 4.7 Volt at all actuators.
I connected a new actuator at right mix door wire. No action.
Calibration was done several times with pulled fuse and also with scan tool.
Expert:  Pete replied 1 year ago.

O.k.,I suspect there is a wiring connection issue causing this.The wiring leads from the HVAC control module to the junction block at the instrument panel then from the junction block to the actuators.I suspect the wiring or connection/terminal fault is most likely at this junction block itself.I have seen pulled connectors,damaged wiring and terminals pulled loose from the junction block or connectors cause this here.On the right side of the dash is this junction block that the HVAC connectors run to as seen below.Check these connections and wiring at the back of the junction block to see if any are damaged or pulled out any.If a fault is found it will need corrected.If this is checked and found o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete.

Customer: replied 1 year ago.
I checked the junktion block and it looks like new from both sides, no corrosion or damages. Pic attached. 4.8 Volt on the correct wires, yellow and lightblue/black. Anything else I can measure? Just wondering, if the head unit does not command anything to the actuators, the problem is at this source, not in the output circuits. What can prevent the head unit from commanding? Its just commanding the mode door, not the 3 other doors.
Expert:  Pete replied 1 year ago.

Is your ac model the AUTO controls on the AC head unit or manual with no AUTO features?

Customer: replied 1 year ago.
I bought this, to check if the head unit is the problem:
http://www.ebay.de/itm/291548092824
Expert:  Pete replied 1 year ago.

O.k.,this is the AUTO model head unit.ON this model the only way to recalibrate the actuators to where the head unit will operate them properly is with a scan tool that will plug into your vehicles data port and communicate with the head unit and that can do the relearn.MOst of the time this requires a GM Tech 2 scan tool to do this or similar high end scan tool to do this.If you only tried the manual recalibration the scan tool recalibration needs done.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete.

Expert:  Pete replied 1 year ago.

Some also need programmed by a GM dealer once installed in your vehicle in order for it to operate properly.

Customer: replied 1 year ago.
I have the paper workshop manual Part 1 and 2 and I have a scan tool. The recalibration works with my scan tool. I hear the mode door working during calibration. You mean the calibration, where the workshop manual says it needs about 40 seconds? Or another kind of calibration? On wich page of the manual is it explained?
Expert:  Pete replied 1 year ago.

Try this,locate all heater and ac fuses in the interior and under hood fuse panels and remove them for 5 minutes with the key off.Then reinsert the fuses and turn on the key without touching any heater or ac controls and wait one minute with the key on.Then start the engine and operate the heater and ac controls and see if it all operates properly then.Let me know if this works.

Thanks Pete

Customer: replied 1 year ago.
I did this several times. With the old and the new head unit. This is the same calibration procedure like with the scan tool.
Expert:  Pete replied 1 year ago.

Was this the same issue with the old head unit and new/used head unit installed or did this only start to occur when the new/used head unit was installed?

Customer: replied 1 year ago.
It was the same issue before. Buying a new headunit solved not the problem.
Expert:  Pete replied 1 year ago.

O.k.,with a new head unit,new actuators installed and the calibration attempted manually and with the scan tool the only thing I can see that will cause this issue here is a wiring fault in the dash needing located and repaired.If you operated any of the dash actuators without them being installed to the heater box this can damage the actuators to where they would need replaced again.If these are o.k. the only thing it can be here is faulty wiring needing located and repaired and you may have to trace all wiring from the head unit to each actuator to locate the fault.

Thanks Pete

Customer: replied 1 year ago.
OK, I will continue searching and keep you updated
Expert:  Pete replied 1 year ago.

Sounds good.Let me know what you come up with here and feel free to rate my help if you like.

Thanks Pete

Customer: replied 1 year ago.
We are helpless now. I need to know if any other module can affect the funktions of the HVAC module via the databus. Everything else is working at this H2, but we have no communication/access to the speedometer, and a databus error on the body module. I really hate to replace other modules. They are all working and are doing what they should..
Expert:  Pete replied 1 year ago.

Looking at the info on this model here the only thing I see myself that will cause this issue with what has already been checked and replaced is the wiring itself leading from the heater controller on the dash to the actuators on the heater box.Is there any way you can check this wiring over to see if you locate the issue at all or has this already been done?

Let me know,thanks Pete.