Climate Control System Symptom Troubleshooting Index (Climate Control)

Symptom	Diagnostic Procedure	Also Check for
The blower and the heater controls and the A/C system do not work	Probable cause: Climate control unit malfunction Do the climate control power and ground circuit troubleshooting	Climate control DTCs Blown fuse No. C24 (7.5 A) in the under-dash fuse/relay box Poor ground at G403 Poor or loose connections at the terminals
The A/C compressor clutch and the A/C condenser/radiator fans are inoperative, but the blower and heater controls work	Probable cause: A/C pressure sensor circuit malfunction or evaporator temperature sensor circuit malfunction Troubleshoot the A/C pressure sensor circuit: A/C pressure sensor circuit low voltage A/C pressure sensor circuit high voltage NOTE: The A/C pressure sensor circuit can malfunction without setting a DTC	Climate control DTCs PGM-FI DTCs Abnormal A/C system pressures Faulty evaporator temperature sensor Poor or loose connections at the terminals
The A/C compressor clutch does not engage, but the A/C condenser/radiator fans operate, and the blower and heater controls work	Probable cause: No power to the A/C compressor clutch Do the A/C compressor clutch circuit troubleshooting	Climate control DTCs Blown fuse No. B14 (7.5 A) in the under-hood fuse/relay box Abnormal A/C system pressures Poor or loose connections at the terminals
The A/C condenser/radiator fans do not run at low speed with the A/C on, but the blower and heater controls work normally	Probable cause: A/C condenser/radiator fan low speed circuit malfunction Do the radiator and A/C condenser fan low speed circuit troubleshooting	Climate control DTCs PGM-FI DTCs Blown fuse No. B12 (30 A) in the under-hood fuse/relay box Poor ground at G301 Poor or loose connections at the terminals
The A/C condenser/radiator fans do not run at high speed, but do run at low speed with the A/C on	Probable cause: Malfunction in the fan(s) high speed circuit Do the following troubleshooting as needed: A/C condenser fan high speed circuit troubleshooting Radiator fan high speed circuit troubleshooting	Climate control DTCs PGM-FI DTCs Blown fuses No. B23 (30 A) and No. B31 (7.5 A) in the under-hood fuse/relay box Poor ground at G301 Poor or loose connections at the terminals
The blower fan runs slower than expected in cold weather (when in AUTO mode) NOTE: It is normal for the blower fan to run slowly until the coolant temperature rises when in AUTO mode	Probable cause: Engine coolant temperature (ECT) circuit malfunction Troubleshooting the ECT sensor circuit: ECT sensor 2 circuit low voltage ECT sensor 2 circuit high voltage	Climate control DTCs PGM-FI DTCs Blower motor operation

Symptom	Diagnostic Procedure	Also Check for
The A/C compressor clutch cycles rapidly on and off	Probable cause: A/C system is overcharged (Excessive pressure on high side of system causing pressure sensor to turn A/C compressor off) Radiator and/or A/C condenser fan inoperative Low idle speed	Climate control DTCs Faulty A/C pressure sensor
Driver's and passenger's side vent temperatures vary by more than 20 deg.F (11 deg.C)	Probable causes: The recirculation control door or the air mix doors are malfunctioning Do the following troubleshooting: Driver's air mix control motor test Passenger's air mix control motor test (dual A/C type) Probable causes: Low refrigerant charge	Climate control DTCs Poor or loose connections at the terminals
HDS does not communicate with the climate control unit or the vehicle	Troubleshoot the DLC circuit
Insufficient heating	Check the coolant level Check the radiator cap Check the engine coolant temperature (ECT) during normal operation with the HDS Check the heater core inlet hose temperature: If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump If it is HOT, check for restrictions in the heater core. Back flush or replace the heater core Check the operation of the air mix doors: Driver's Passenger's (dual A/C type) Check the blower motor unit for obstructions Check for air leaks around the ducts and vents	Climate control DTCs