1986 - 1988 Corvette: Service Bulletin: New Heater and Air Condition Control Head Assembly

Subject:   New Heater and Air Condition Control Head Assembly
Model and Year:   1986 - 1988 Corvette Coupes Only
Source:  Chevrolet Dealer Service Bulletin
Bulletin No:   88-230-1A
Section:   1A
Date:    May, 1988

TO:  ALL CHEVROLET DEALERS

A new heater and air conditioning control head assembly has been released for production and service of the above models.  This control head has a new calibration (software change) that determines and remembers the air mix door position.

This calibration feature runs the air mix door full travel (Full Cold position to Full Hot position) after start-up from a battery reset and remembers the size of the travel.  The control then divides the measured feedback for air mix door position.  The time for the air mix door motor to travel full travel will be about 1.5 minutes.

NOTICE:  THE BLOWER MOTOR WILL BE OFF FOR THE CALIBRATION TIME PERIOD (1.5 MIN.). THIS WILL BE THE ONLY INDICATION GIVEN TO THE OPERATOR OR CUSTOMER THAT THE CALIBRATION FEATURE IS IN PROCESS.

- If an "open" in the air mix door motor circuit is repaired, it will cause the system to recalibrate.

- Any work done on the air mix door motor should be followed by a battery or control head electrical disconnect/reconnect to cause a recalibration process to occur.

The new control head service parts numbers and the VIN breakpoints for production vehicles with new control head are as follows:

These new control heads can be used on vehicles prior to the breakpoints to address reported conditions of inconsistent in-car temperature control.  This however, should only be done if the customer has commented on a poor in-car temperature condition.

Use applicable labor operation and time.

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