Diagnostics and testing of air conditioning (Discovery 3)

Inspection and verification

1. Make sure the customer's complaint is valid.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical factors	Electrical Factors
Auxiliary drive belt condition and tension Condition and installation of the compressor Capacitor condition and installation/blocking Air conditioning hoses and pipes Condition and installation of the receiver/dryer Cooling Fan	Fuses Wiring harnesses electrical connector (s) Relay Sensors Panel (And) management Air conditioning compressor

3. If an obvious cause of a problem you identified or described by a customer is found, resolve it before proceeding to the next steps (if possible).

4. Use an approved diagnostic system or scan tool (tester), to retrieve all DTCs before referring to the symptom table or DTC index (DTC).

Clear all DTCs after troubleshooting.

Symptom table

Symptom	Possible reasons	Action
Poor cooling or no cooling	Drive belt failure Compressor failure Malfunction of the electric motor / damper distribution Refrigerant leak Malfunction of the temperature sensor in the passenger compartment Refrigerant pressure sensor malfunction	Check the condition and tension of the drive belt (see visual inspection). Check compressor operation (monitor the compressor while the engine is idling with the A/C on). If the compressor runs erratically or does not work. Perform a distribution motor self-test. See the relevant section of the workshop manual. Check for sensor DTCs. Refer to the DTC Index. Check the refrigerant system using your service station.
Noise	Drive belt failure Compressor failure Compressor pulley contamination Increased amount of refrigerant	Make sure the air conditioner is the source of the noise; to do this, listen to the noise with the air conditioner turned off. See the relevant section of the workshop manual. Check the refrigerant system using your service station.
Water intrusion into the cabin	Leak in heater core Plugged evaporator drain pipes	Check for lack of coolant If necessary, check the pressurized cooling system. Check and, if necessary, clean the evaporator drain pipes.

DTC index

NOTE: Universal Scan Tools cannot read the listed codes 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 problem (the last 2 digits give additional information read by the diagnostic system approved by the manufacturer).

DTC	Description	Possible reason	Action
B1A6111	Cabin air temperature sensor	Outside air temperature sensor signal circuit short to ground	Check the outdoor air temperature sensor circuit according to the electrical manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
B1A6115	Cabin temperature sensor signal circuit	Outside air temperature sensor signal circuit high resistance In-car temperature sensor signal circuit short to voltage	Check the outdoor air temperature sensor circuit according to the electrical manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
B1A6211	Pressure meter	A/C refrigerant pressure sensor signal circuit short to ground	Check the pressure sensor circuit according to the electrical manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
B1A6215	Pressure meter	A/C refrigerant pressure sensor signal circuit short to battery	Check the pressure sensor circuit according to the electrical manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
B1A7001	Compressor Solenoid Positive Power Circuit	Refrigerant line solenoid valve power circuit short circuit to ground Refrigerant line solenoid valve power circuit short circuit to battery Refrigerant line solenoid valve: high temperature	Check the refrigerant solenoid valve circuit according to the electrical manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
B1B7884	System pressure	Pressure signal below acceptable range Refrigerant leak	Check for pressure sensor DTCs. Check the refrigerant system using a suitable charging station.
B1B7885	System pressure	Pressure signal over range Capacitor failure Cooling fan failure	Check for pressure sensor DTCs. Check the condenser for damage/blockage and the operation of the cooling fan. Check the refrigerant system using a suitable charging station.