Air conditioning diagnostics and testing (Discovery 3)

Inspection and verification

1. Ensure that the customer's complaint is justified.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical factors	Electrical factors
Condition and tension of the auxiliary drive belt Compressor condition and installation Capacitor status and installation/locking Air Conditioner Hoses and Pipes Receiver/dryer condition and installation Cooling fan	Fuses and fuses Wiring harnesses Electrical connector(s) Relay Sensors Control panel(s) Air conditioning compressor

3. If an obvious cause for the problem you identified or the customer described is found, resolve it before moving on to further action. (if possible).

4. Use the approved diagnostic system or scan tool to retrieve all diagnostic trouble codes (DTCs) before referring to the symptom chart or DTC index.

Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reasons	Action
Poor cooling or no cooling	Drive belt failure Compressor failure Electric motor/distribution flap malfunction Refrigerant leak Malfunction of the temperature sensor in the car interior Refrigerant pressure sensor malfunction	Check the condition and tension of the drive belt (see visual inspection). Check the compressor operation (monitor the compressor while the engine is idling with the air conditioner on). If the compressor operates erratically or does not operate. Perform the distribution motor self-test. Refer to the appropriate section of the service station manual. Check for DTCs for the sensor. Refer to the DTC Index. Have the refrigerant system checked by your service station.
Noise	Drive belt failure Compressor failure Compressor pulley contamination Increased amount of refrigerant	Make sure the source of the noise is the air conditioner.; to do this, listen to the noise with the air conditioner turned off. See the relevant section of the service station manual. Check the refrigerant system using your service station.
Water ingress into the cabin	Leak in the heater radiator Blockage of evaporator drain pipes	Check for low coolant. Pressure test the cooling system if necessary. Check and clean the evaporator drain lines if necessary.

DTC Index

NOTE: Generic scan tools cannot read the codes listed or can only read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7-digit code to identify the fault. (the last 2 digits provide additional information readable by a manufacturer approved diagnostic system).

DTC	Description	Possible reason	Action
B1A6111	Cabin air temperature sensor	Outside Air Temperature Sensor Signal Circuit Short to Ground	According to the electrical manual, check the outside air temperature sensor circuit. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1A6115	Interior Temperature Sensor Signal Circuit	Outside Air Temperature Sensor Signal Circuit High Resistance Interior Temperature Sensor Signal Circuit: Short to Battery Positive	According to the electrical manual, check the outside air temperature sensor circuit. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1A6211	Pressure sensor	A/C Refrigerant Pressure Sensor Signal Circuit Short to Ground	According to the electrical manual, check the pressure sensor circuit. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1A6215	Pressure sensor	A/C Refrigerant Pressure Sensor Signal Circuit: Short to Battery Positive	According to the electrical manual, check the pressure sensor circuit. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1A7001	Compressor Solenoid Valve Positive Power Circuit	Refrigerant Line Solenoid Valve Power Circuit: Short to Ground Electrical power supply circuit of the refrigerant line solenoid valve: short circuit to + battery Refrigerant line solenoid valve: high temperature	Check the refrigerant solenoid circuit according to the electrical manual. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1B7884	Pressure in the system	Pressure signal below acceptable range Refrigerant leak	Check for pressure sensor DTCs. Check the refrigerant system using a suitable charging station.
B1B7885	Pressure in the system	Pressure signal above acceptable range Capacitor failure Cooling fan malfunction	Check for DTCs for the pressure sensor. Check the condenser for damage/blockage and the operation of the cooling fan. Check the refrigerant system using a suitable charging station.