HVAC Compressor Clutch Does Not Engage. Pontiac Sunfire 2002

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2002 🢒 Sunfire 🢒 Engine 🢒 Engine Cooling 🢒 HVAC Compressor Clutch Does Not Engage

Test Description

The numbers below refer to the step numbers on the diagnostic table.

The A/C compressor relay output is disabled if engine coolant temperature is above 121°C (250°F).

There are two A/C request outputs from the HVAC control assembly. One request comes from the mode switch when in defrost or recirculation mode and the other request comes from the A/C switch. If there is an open in the A/C request circuit before the splice, the A/C may operate from the mode switch, but not from the A/C switch or vice versa.

The HVAC control assembly is inoperative when the HVAC control unit does not respond to any operator control request to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.

Be sure to check both of the request circuits before the splice.

Step

Action

Yes

Schematic Reference: HVAC Schematics

DEFINITION: The A/C compressor clutch will not engage when an A/C request has been made and a Powertrain DTC has not been set.

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

Install a scan tool.
Start the engine.
With a scan tool, observe the ECT parameter in the Powertrain data list.

Does the scan tool indicate that the ECT parameter is below 121°C (250°F)?

Go to Step 3

Go to Engine Overheating in Engine Cooling

Important: The outside air temperature must be above 3°C (36°F).

Start the engine.
Place the blower motor switch in the maximum speed position.
Place the A/C request switch in the ON position.
Place the air temperature switch in the coldest position.
Cycle the mode switch through each position except OFF.

Does the A/C compressor operate in each mode position?

Go to Testing for Intermittent Conditions and Poor Connections in wiring systems

Go to Step 4

Does the A/C compressor operate with the mode switch in the defrost or recirculation positions?

Go to Step 5

Go to Step 6

Place the mode switch to the vent position.

Does the A/C compressor operate?

Go to Step 6

Go to Step 19

Park the vehicle inside or in the shade.
Open the windows in order to ventilate the interior of the vehicle.
Turn OFF the ignition.
Install the J 43600 ACR 2000.
Record the outside air temperature at the vehicle.
Record readings of the low and high side STATIC pressures.
Compare the pressure values with the specifications for the ambient air temperature. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Are the pressure values within specification for the ambient air temperature, and within 103 kPa (15 psi) of each other?

Go to Step 7

Go to Leak Testing in Heating, Ventilation and Air Conditioning

Turn ON the ignition, with the engine OFF.
With a scan tool, observe the A/C High Side pressure sensor parameter in the Powertrain data list.
Compare the A/C high side pressure on the scan tool to the high side pressure value on the ACR2000.

Are the high side pressure values with 103 kpa (15 psi) of each other?

Go to Step 8

Go to Step 21

Is the HVAC control assembly inoperative?

Go to Step 12

Go to Step 9

Start the engine.
With a scan tool, observe the A/C Request parameter in the Powertrain data list 2.
Place the blower motor switch in the maximum position.
Place the mode switch in the recirculation position.

Does the scan tool indicate that the A/C Request parameter is YES?

Go to Step 10

Go to Step 14

With a scan tool, observe the A/C Relay Commanded parameter in the Powertrain data list 2.

Does the scan tool indicate that the A/C Relay Commanded parameter is ON?

Go to Step 11

Go to Step 32

With a scan tool, command the A/C compressor clutch relay ON and OFF.

Does the A/C compressor clutch relay turn ON and OFF with each command?

Go to Step 15

Go to Step 17

Test the ignition voltage circuit to the HVAC control assembly for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?