A/C - LED Indicator Failure

9232bmw01

Group 64
Heating and Air Conditioning


Bulletin Number
64 08 92 (3521)


Woodcliff Lake, NJ
April 1992
Product Engineering


SUBJECT:
Air Conditioning LED Indicator Failure

MODELS:
E34 w/M50 engine (from 9/90 production)

Symptom:
The LED Indicators in the control buttons for air conditioning and recirculation do not light up in extremely cold weather.

Cause:
At an ambient temperature of below -15 degrees F, the pressure in the refrigerant circuit can drop below the high/low pressure switch cutoff. The switch opens the compressor clutch circuit to prevent compressor damage.

However, since 9/90 production the high/low pressure switch is part of the control wire circuit of the K19 compressor relay. This control wire is monitored by the air conditioning control unit. The control unit interprets the shutdown as an "interruption" and logs code "44 - A/C Relay - Aux Fan Relay Stage 1 " in the IHKR fault code memory. Additionally, the LED indicator lamps on the IHKR front panel are deactivated.

Correction:
If a complaint is experienced with a vehicle, or a fault is discovered in the control system, an adaptor lead (P/N 61 12 4 206 457) should be added to the electrical connection of the pressure switch. The switch is mounted on the receiver-drier and the connector is fastened with a plastic clip to the inner passenger side fender. The switch is located in the front passengerside corner of the engine compartment, behind the head light assembly. Removing the washer fluid bottle will permit easy access to the connector. Tie-wrap the loose connector end to the other wiring.

A resistor has been incorporated into the adaptor which allows the high/low pressure switch to protect the compressor, but prevents the deactivation of the LED indicator lamps on the IHKR front panel.

Note:
Check the overall operation of the system before performing this repair. A major loss of refrigerant or K19 relay failure could cause identical effects.
Parts
Information: Description Part Number
Pressure Switch Adaptor 61 12 4 206 457


Warranty
Information: Parts and labor covered under the terms of the applicable BMW New Car Limited Warranty.

Defect code: 64 53 09 79 00
Labor operation: 00 50 366
Labor allowance: 5 FRU