A/C - Inoperative, Compressor Not Engaged
GROUP 64
Heating and Air Conditioning
Bulletin Number
64 04 99
Woodcliff Lake, NJ
September 1999
Product Engineering
SUBJECT:
DIAGNOSIS HINT: Intermittent - No A/C on E38, E39, and E46
MODEL:
E38, E39 produced 9/98 and later; All E46
Situation:
Customer complaint of no A/C, compressor not engaged.
Cause:
424
Possible A/C pressure sensor malfunction.
Procedure:
Using the DIS/MODIC, compare the pressure sensor output to the A/C manifold gauge reading on the high pressure line.
Note:
All E46, E38 (9198 and later) and E39 (9198 and later), use a pressure sensor on the high side A/C line(at the drier). The pressure sensor has a
variable output signal as compared to the pressure switch, which is "on - off". The switch is not interchangeable with the sensor. To check the
A/C pressure sensor:
1. Connect the DIS/MODIC to the vehicle.
2. Select: "Control Unit Functions"
Select: " C Control System"
Select: "Pressure sensor" and "Display"
The pressure sensor value will be displayed under "Messages and Results".
3. Connect the A/C manifold gauges to the high and low pressure valves.
4. The high and low side gauges should read approximately 90 - 120 psi (depending on the vehicle and temperature). Before proceeding, make
sure the high and low side pressures are equal. if the gauges are not equal, wait until the system pressures equalize.
5. Select: "Control Unit Functions"
Select: "A/C Control System"
Select: "Pressure sensor" and "Display"
6. The pressure sensor value will be displayed under "Messages and Results". Compare the DIS/MODIC pressure sensor value to the high side
manifold gauge.
7. if the high side manifold gauge is in "psi" only, then the DIS/MODIC reading must be multiplied by 14.5.
(pressure sensor value) bar X 14.5 = (pressure sensor value) psi
8. The values should be within 锟斤拷 10% (due to gauge calibration).
9. If the pressure sensor value is "negative" or not within 锟斤拷 10% of the manifold gauge value then the sensor must be replaced.
Note:
The A/C system must be evacuated before replacing the sensor.
Parts Information:
Refer to the EPC.
Warranty Information:
Diagnostic hint for information only.
