Climate Control System Symptom Troubleshooting Index

Symptom	Diagnostic procedure	Also check for
The blower and 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 - Refer to: How to Troubleshoot the Body Electrical, or How to Troubleshoot the Climate Control System Blown fuse No. C23 (7.5 A) in the under-dash fuse/relay box Poor ground at G405 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	Climate control DTCs - Refer to: How to Troubleshoot the Body Electrical, or How to Troubleshoot the Climate Control System Abnormal A/C system pressures - Refer to: A/C System Test (1234yf), or A/C System Test (134a) Faulty evaporator temperature sensor Poor or loose connections at the terminals
The A/C compressor clutch does not engage, but the A/C condenser and 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 - Refer to: A/C Compressor Clutch Circuit Troubleshooting (Without Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2016 2017 2018: With Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2019 2020 2021: With Climate Control) .	Climate control DTCs - Refer to: How to Troubleshoot the Body Electrical, or How to Troubleshoot the Climate Control System Blown fuse No. A20 (7.5 A) in the under-hood fuse/relay box Abnormal A/C system pressures - Refer to: A/C System Test (1234yf), or A/C System Test (134a) 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 - Refer to: A/C Condenser Fan High Speed Circuit Troubleshooting, or Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting	Climate control DTCs - Refer to: How to Troubleshoot the Climate Control System, or How to Troubleshoot the Body Electrical PGM-FI DTCs - Refer to: How to Troubleshoot the Brake Booster Pressure Monitoring System, or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (6-Speed A/T) Blown fuse No. A2-1 (30 A) in the under-hood fuse/relay box Poor ground at G204 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 - Refer to: A/C Condenser Fan High Speed Circuit Troubleshooting, or Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting Radiator fan high speed circuit troubleshooting - Refer to: Radiator Fan High Speed Circuit Troubleshooting (2019 2020 2021: 9-Speed A/T) or Radiator Fan High Speed Circuit Troubleshooting (6-Speed A/T, 2016 2017 2018: 9-Speed A/T) or Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting	Climate control DTCs - Refer to: How to Troubleshoot the Body Electrical, or How to Troubleshoot the Climate Control System PGM-FI DTCs - Refer to: How to Troubleshoot the Brake Booster Pressure Monitoring System, or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (6-Speed A/T) Blown fuse No. A1-5 (30 A) or No. A2-1 (30 A) in the under-hood fuse/relay box Poor ground at G202 or G204 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 Do the ECT sensor 2 circuit range/performance problem	Climate control DTCs - Refer to: How to Troubleshoot the Climate Control System, or How to Troubleshoot the Body Electrical PGM-FI DTCs - Refer to: How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (6-Speed A/T), or How to Troubleshoot the Brake Booster Pressure Monitoring System Manual 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 the A/C compressor off) Radiator and/or A/C condenser fan inoperative Low idle speed Evaporator temperature sensor malfunction Do the evaporator temperature sensor test Front - Refer to: Evaporator Temperature Sensor Removal, Installation, and Test, or Rear Evaporator Temperature Sensor Removal, Installation, and Test Rear - Refer to: Evaporator Temperature Sensor Removal, Installation, and Test, or Rear Evaporator Temperature Sensor Removal, Installation, and Test	Climate control DTCs - Refer to: How to Troubleshoot the Body Electrical, or How to Troubleshoot the Climate Control System Do the A/C compressor clutch circuit troubleshooting - Refer to: A/C Compressor Clutch Circuit Troubleshooting (Without Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2016 2017 2018: With Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2019 2020 2021: With Climate Control) , and look for an intermittent problem Faulty A/C pressure sensor
The A/C compressor clutch does not disengage when the A/C switch is off	Probable cause: The A/C compressor clutch circuit is on (energized) continuously, shorted to ground, stuck A/C compressor clutch relay, or the A/C compressor clutch is mechanically jammed Do the A/C compressor clutch circuit troubleshooting - Refer to: A/C Compressor Clutch Circuit Troubleshooting (Without Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2016 2017 2018: With Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2019 2020 2021: With Climate Control) , and repair any circuit problems If the A/C compressor clutch circuit is OK, then do the A/C compressor clutch check , and repair any problems with the A/C compressor clutch	The A/C compressor relief valve. If it has vented refrigerant to the atmosphere, correct the problem with the A/C compressor clutch or clutch circuit, then replace the A/C compressor relief valve
The A/C compressor relief valve has vented refrigerant NOTE: This indicates the A/C system high side pressure was high	Probable cause: A high-side restriction, the A/C condenser/radiator fans are inoperative, or the A/C compressor clutch is not disengaging If the fans and A/C compressor clutch operate normally, feel the lines for restrictions Do the A/C system contamination inspection - Refer to: A/C System Inspection, or A/C System Contamination Inspection If the A/C compressor clutch will not disengage, troubleshoot the A/C compressor clutch circuit - Refer to: A/C Compressor Clutch Circuit Troubleshooting (Without Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2016 2017 2018: With Climate Control), or A/C Compressor Clutch Circuit Troubleshooting (2019 2020 2021: With Climate Control) , and check for mechanical problems If the fans are inoperative, do the radiator and A/C condenser fan low speed circuit troubleshooting - Refer to: A/C Condenser Fan High Speed Circuit Troubleshooting, or Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting	PGM-FI DTCs - Refer to: How to Troubleshoot the Brake Booster Pressure Monitoring System, or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (6-Speed A/T)
Driver's and passenger's side vent temperatures vary by more than 20 °F (11 °C)	Probable causes: The air mix doors are malfunctioning Do the following troubleshooting: Driver's air mix control motor test Passenger's air mix control motor test Probable causes: Low refrigerant charge	Climate control DTCs - Refer to: How to Troubleshoot the Climate Control System, or How to Troubleshoot the Body Electrical Poor or loose connections at the terminals
HDS does not communicate with the climate control unit or the vehicle	Troubleshoot the DLC circuit - Refer to: DLC Circuit Troubleshooting (2016 2017 2018), or DLC Circuit Troubleshooting (2019 2020 2021: Without CAN Gateway), or DLC Circuit Troubleshooting (2019 2020 2021: With CAN Gateway)
Insufficient heating	1. Check the coolant level 2. Check the radiator cap 3. Check the coolant temperature during normal operation 4. 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 - Refer to: Heater Unit/Core Removal and Installation (Without Climate Control), or Heater Unit/Core Removal and Installation (With Climate Control) 5. Check the operation of the air mix doors: Driver's Passenger's Rear 6. Check the blower motor unit for obstructions 7. Check for air leaks around the ducts and vents	Climate control DTCs - Refer to: How to Troubleshoot the Body Electrical, or How to Troubleshoot the Climate Control System