Symptom Troubleshooting Index: Notes

WARNING: This page is about a different car, the 2009 Acura MDX, 2008 Acura MDX, and 2007 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM TROUBLESHOOTING CHART

Symptom	Diagnostic procedure	Also check for
Rear mode control doors do not change between ceiling vents (cool) and floor vents (hot)	Rear mode control motor circuit troubleshooting (see REAR MODE CONTROL MOTOR CIRCUIT TROUBLESHOOTING )	HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Blown fuse No. 30 (10 A) in the under-dash fuse/relay box Cleanliness and tightness of all terminals
Blower, heater controls, and A/C do not work	Climate control unit troubleshooting (see CLIMATE CONTROL UNIT TROUBLESHOOTING )	HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Blown fuse No. 30 (10 A) in the under-dash fuse/relay box Poor ground at G506 (see GROUND TO COMPONENTS INDEX ) Cleanliness and tightness of all terminals
Both fans do not run at low speed with the A/C on (but the A/C compressor runs with the A/C on)	Radiator and A/C condenser fan low speed circuit troubleshooting (see RADIATOR AND A/C CONDENSER FAN LOW SPEED CIRCUIT TROUBLESHOOTING )	HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Blown fuse No. 15 (30 A) in the relay block, and No. 30 (10 A) in the under-dash fuse/ relay box Poor ground at G301 (see GROUND TO COMPONENTS INDEX ) Cleanliness and tightness of all terminals
The A/C condenser fan does not run at high speed (but both fans run at low speed and the A/C compressor operates with the A/C on)	A/C condenser fan high speed circuit troubleshooting (see A/C CONDENSER FAN HIGH SPEED CIRCUIT TROUBLESHOOTING )	HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Cleanliness and tightness of all terminals
Both fans do not run at high speed with the A/C on (but both fans run at low speed and the A/C compressor operates with the A/C on)	ECT troubleshooting: ECT sensor 2 circuit low voltage (see DTC P2184: ECT SENSOR 2 CIRCUIT LOW VOLTAGE ), ECT sensor 2 circuit high voltage (see DTC P2185: ECT SENSOR 2 CIRCUIT HIGH VOLTAGE )	Powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Cleanliness and tightness of all terminals
The A/C compressor clutch does not engage (but both fans run with the A/C on)	A/C compressor clutch circuit troubleshooting (see A/C COMPRESSOR CLUTCH CIRCUIT TROUBLESHOOTING )	HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Blown fuse No. 17 (7.5 A) in the relay block, and No. 30 (10 A) in the under-dash fuse/ relay box Blower motor operation Cleanliness and tightness of all terminals
Blower fan(s) runs slower than expected in cold weather	ECT troubleshooting: ECT sensor 2 circuit low voltage (see DTC P2184: ECT SENSOR 2 CIRCUIT LOW VOLTAGE ), ECT sensor 2 circuit high voltage (see DTC P2185: ECT SENSOR 2 CIRCUIT HIGH VOLTAGE ) NOTE: It is normal for the blower(s) to run slowly until the engine coolant temperature begins to rise. If the blower continues to run slowly for an abnormal length of time, continue to troubleshoot the problem.	Powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) Blower motor operation
HDS does not communicate with the climate control unit or the vehicle	Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING )
Insufficient heating	Check the coolant level (see COOLANT CHECK ) Check the radiator cap (see RADIATOR CAP TEST ) Check the operation of the air mix control motor and door (see DRIVER'S AIR MIX CONTROL MOTOR TEST ) Check the coolant temperature Check the operation of the heater valve (see HEATER VALVE CABLE ADJUSTMENT ) Check the blower motor unit for obstructions Check for air leaks around the ducts and vents Check the inlet hose temperature If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, and a damaged or leaking water pump. If it is HOT, check for restrictions in the heater core. Back flush the heater core using standard commercially available equipment, or replace the heater core.	Damaged cylinder head gasket