Air conditioner, fault tables

Air conditioner, fault tables

10000165-en

Blower malfunctions

Page 1 of 4

Malfunction Cause Measures

Blower not working Fuse defective or loose Check fuse seating, plug in correctly if necessary. Replace defective fuse. Reappearance of the defect after a short time indicates a short-circuit. Check blower for blocking or other defects and rectify. Loose connector Check that connector at the side of the unit is firmly in place and plug in properly if necessary. Check connections at blower switch. Open the unit and check electrical connections inside.

Connecting cable damaged or ripped off Replace cable. Observe the correct cable run and connections.

Wrong electrical connections

Check connecting cables and, if necessary, reconnect properly. Blower switch defective Replace with a new OEM part. Blower assembly blocked Eliminate cause of blockage, e.g. by removing foreign object from rotor. If necessary, install new blower. Blower motor defective Replace blower.

Blower cannot be stopped Blower switch defective Replace blower switch.

Blower performance reduced Wrong nominal supply voltage

Nominal voltage of conditioner and of on-board electrical system must be identical. Replace blower. Contacts dirty Clean connector contacts. Work carefully to avoid shortcircuits.

Heat exchanger heavily soiled Clean carefully to avoid any damage resulting in leaks.

Blower ducts obstructed Check air ducts and outlets for obstructions and remove any foreign objects. Correcting malfunctions.

Insufficient cooling performance

Page 2 of 4

Malfunction Cause Measures

Open circuit in compressor solenoid

Compressor not Check power supply to the clutch. working

Thermostat defective Replace thermostat. V-belts loose or broken Adjust V-belt tension, replace V-belt. Belt pulley not turning although magnetic clutch is engaged Check compressor and replace if necessary.

Compressor clutch slipping Repair clutch or replace compressor.

Evaporator flooded Expansion valve jammed or stuck in open position Replace expansion valve (block valve).

Evaporator frozen up Thermostat sensor in wrong position Install sensor in the correct position.

Evaporator clogged up Cooling fins dirty Clean evaporator. Loss of refrigerant Refrigerant line defective Check all lines for discontinuities caused by external influences or chafing. Leaks in the system Evacuate the system, refill, check for leaks and repair. Filter mat (recirculated air) Filter mat clogged Clean or replace filter mat. Air filter element (fresh air) Air filter element clogged Clean or replace air filter element. See also: “Heating, cleaning the filter element”. Heating is on Bowden cable wrongly centred or defective Adjust Bowden cable (see: “Heater valve, adjusting the Bowden cable”) or replace.

Insufficient heating performance

Page 3 of 4

Malfunction Cause Measures

Heating not working Coolant still cold Wait until the engine has reached its operating temperature. Water valve closed Open the heater valve (see operating instructions: “Ventilation and heating”).

Water lines kinked or crushed Eliminate cause of the fault.

Heating performance reduced

Heating cannot be stopped Heat exchanger, filter mat or air filter element (heating) heavily soiled Clean carefully to avoid any damage resulting in leaks. When too heavily soiled, replace filter mat or air filter element. .

Insufficient volume of water flowing through heat exchanger

Water lines crushed or kinked, change position of hoses. Insufficient water pump pressure (remedial action see above). Air in heat exchanger The radiator is self-venting when the pump pressure is high enough. Install an auxiliary or more powerful water pump.

Conditioning unit underdimensioned If necessary, install an additional heating or a more powerful conditioning unit.

Bowden cable controlling the heating valve wrongly adjusted Heater valve not installed correctly in flow and/or reflow line

Actuation mechanism or Bowden cable defective Readjust the Bowden cable.

Check valve mounting position with respect to flow and reflow direction and correct if necessary. See also: “Air conditioner, inspection and servicing work”. Check the actuation mechanism or Bowden cable and replace if necessary.

Air distribution flaps cannot be adjusted Flap hinges sluggish Check flap and lubricate if necessary. Flap deformed Check flap. Flap blocked by foreign object Check flap and remove foreign object if necessary.

Conditioner very noisy

Malfunction Cause Measures

Conditioner very noisy V-belt loose or excessively worn Retension or replace V-belt.

Clutch noisy Repair clutch. Compressor supporting bracket loose or wornout parts inside the compressor Repair bracket, replace compressor. Page 4 of 4

Blower motor excessively worn Replace blower.

System overfilled Evacuate refrigerant until the high pressure reading is normal again (approved workshop).

Not enough refrigerant in the system Check for leaks, refill the system.