GM Tech2 troubleshot Buick Regal Air Conditioner Control Adjustment issue

(1) In summer, when the weather is hot, air conditioning system in automatic control mode, when the temperature is adjusted to a lower temperature value, the cold wind will not bring out instead of hot wind, and air conditioning system control go to trouble mode or protected mode, the cold / warm mixing stay in the position of hot wind.

(2) In winter, when the weather is cold, air conditioning system has no warm wind, t the cold / warm mixing is locked in the position of cold wind.

Possible Reasons:

The air conditioner cold / warm wind door shaft has manufacturing deviation and the software of air conditioning module has poor suitability, the specific reason as follows:

There are two reasons why it has hot wind when the weather is hot:
(1)possible reason one: the C8 pin of air conditioner control module shows signal there is no electronic currency, after the system set trouble codes, the controlling software become fault mode, and command cold / warm mixing wind door stay in the position where blow hot wind. The main reason is there is no electronic currency in the air conditioner circuit or the sliding resistor in the cold / warm wind door electronic motor; besides, cold / warm wind door shaft has hardware production deviation which may cause voltage higher than 4.98V in the process of adjusting and cause the trouble, but at this time, air conditioner system doesn’t set trouble code, because when the air conditioner control module send out command requesting the temperature adjust to the highest, then the voltage is also the highest, at this time air conditioner system is supposed to blow hot wind.

(2) possible reason two: the C8 pin of air conditioner control module feedback the minimum voltage less than 0.35V but not less than 002 V, at this time air conditioner control module doesn’t set trouble codes, the control software go to protected mode, with the rise of automatic control temperature, protected mode will cancel automatically, then in automatic control mode, air conditioner system will produce hot wind not cold wind when the temperature is set to a lower value. But when the temperature is set to a higher value, the control system can work and the manual control mode can work either.

(3) In cold weather it doesn’t blow warm wind, possible reason: When air conditioner control system in automatic control mode, cold / warm wind door electronic motor show voltage signal ground short circuit or voltage value lower than 0.02V, at this time the control software go to trouble mode and set trouble code B0361 (cold / warm wind door is locked in the position of cold), and both the manual mode and automatic mode of air conditioner control module fail to control, only to disconnect power supply can trouble mode be canceled (Note: if it fail to recover, please instantly connect C1 and C7 port)
(2)Improper operation: in short time, the car owner repeatedly press or choose the function buttons on the air conditioner control panel, which cause a disorder of the control module because air conditioner control module receive many other new command before the previous command hasn’t complete execution.

The way to test:
(1) Firstly, connect GM Tech2 scanner(I ordered from www.obdii365.com ) with Buick Regal, and read out current or history trouble codes for air conditioner control module.

(2) Then measure the voltage of air conditioner control module C8 pin, which help the repairman analyze the specific reason. When air conditioner control module in manual mode, C8 pin ideal voltage is 1-4V, if the tested voltage less than 0.35V at minimum, then the control module is likely to disorder, if the voltage is less than 0.02V, then the control module will definitely disorder.

4. Possible solutions:
(1) Under various conditions, if the voltage of air conditioner control module C8pin is not less than 0.35V, please refer to the trouble code information and the user manual to check the circuit or sliding resistor in the cold / warm wind door electronic motor, if there is any fault, troubleshoot it.
(2) Under various conditions, if the voltage of air conditioner control module C8pin is less than 0.35V, then the possible reason is that cold / warm wind door shaft has manufacturing deviation，there are two solutions to solve the problems.
A. Change the air conditioning container body assembly (or change the cold / warm wind door shaft.
B. Adjust the relative position of the sliding resistors passive gear in the cold / warm wind temperature actuator electronic motor, and make C8 pin Voltage in an idea status. Please attention: only the old cold / warm wind temperature actuator can adjust feedback resistor gear, but the new one can’t do.

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