Loss of Airflow From A/C Outlets after Extended Periods of Highway Driving

After extended periods of highway driving, some customers may notice a loss of airflow from the A/C outlets.

A/C compressor suction set point may be low for some customer usage and driving patterns, resulting in evaporator freeze after extended periods of highway driving.

Adjust A/C compressor set point using the following procedure.

Notice: This procedure should never be repeated on the same A/C compressor. If condition is not corrected by this bulletin, refer to the diagnostic flow chart in the appropriate year "HVAC Service Manual."

1. Confirm with customer that A/C system functions normally in all conditions, except extended driving at highway speeds.

•	If A/C system does not function normally at any other condition , refer to the A/C system diagnostic flow chart in the appropriate year "HVAC Service Manual."

•	If A/C system Functions normally during all other conditions , proceed to the next step.





Important: Engine does not need to be running for the A/C compressor set point adjustment.

2. Locate the set screw on the rear head of the A/C compressor. The set screw will be covered with either a solid silver label or a silver label with the words: CAUTION! DO NOT REMOVE CONTENTS UNDER PRESSURE.

Notice: Do not remove this label.





Caution: Be careful to keep hands clear of the engine cooling fan. The engine cooling fan may operate unexpectedly.

Notice: If the silver label has been broken, or an orange replacement label is present, DO NOT continue with this procedure. Additional adjustment of the set screw could result in reduced A/C system performance at higher ambient temperatures.

3. Determine where the large slot in the set screw is located. The slot can be felt through the label with a screwdriver.

3.1.	Using a utility knife, cut through the label for access to the slot screw (1).

3.2.	Using a permanent ink marker, make a mark on the A/C compressor to indicate the current position of the set screw in relation to the compressor rear head (2).





Caution: Do not turn the set screw on the back of the A/C compressor counterclockwise. The A/C system is under pressure and turning the set screw counterclockwise could cause the set screw and/or hot refrigerant/oil mixture to be discharged under pressure. The refrigerant/oil mixture can cause burns and/or bodily injury.

Notice: Do not turn the set screw more than 1/4 turn clockwise. Adjusting the set point changes the pressure at which the A/C compressor goes to minimum displacement. Increasing the adjustment beyond 1/4 turn clockwise will not make the system colder and could reduce A/C system performance at higher ambient temperatures.

4. Using a large-blade screwdriver, turn the set screw 1/4 turn clockwise as viewed from the rear of the compressor.
5. Using a clean shop towel, wipe the surface area where the silver label is located. Make certain there is no debris or oil present.

Notice: To prevent the A/C compressor set screw from being adjusted again, the orange A/C refrigerant caution label P/N 21031284 must be installed over the old silver label.

6. Install a new orange A/C refrigerant caution label P/N 21031284 over the old silver label that was cut in step 3a.
7. Start the engine and inspect that the A/C system is functioning normally.

P/N 21031284 Label -- A/C Refrig Caution.

To receive credit for this repair during the warranty period, submit a claim through the

Saturn Dealer System as follows: