Troubleshooting by Symptom

Troubleshooting by Symptom

Poor Heater System Performance

CAUTION
Check all fluid levels and adjust as needed, before operating vehicle for extended periods at idle.

Start the engine.
Idle the engine until the thermostat opens (upper radiator hose will be hot) Is the engine at normal operating temperature (approx. 200° F)? If yes, go to the next step. If no, go to step 16.
Set the mode selector to FLOOR mode.
Set the heater control selector to the warmest temperature setting.
Set the blower speed the lowest setting.
Carefully feel the inlet and outlet heater hoses at the heater core. Is the inlet heater hose significantly hotter than the outlet heater hose? If yes, go to step 14. If no, go to the next step.
Set the mode selector to PANEL mode.
Select the maximum blower speed.
Select the warmest temperature setting.
Place a thermometer into the center I/P PANEL air outlet and affix a second thermometer to the heater core outlet heater hose.
Record the temperature at the center I/P PANEL air outlet and at the heater core outlet heater hose. Are the two temperature readings about equal? If yes, go to the next step. If no, go to step 13.
Inspect and repair the cowl, cowl area, recirculation door, and the HVAC evaporator/heater core case for cold air leaks. Repair any problems found, go to step 17.
Inspect the temperature door operation. Repair any problems found, go to step 17.
Turn OFF the engine. Back-flush the heater core. Start the engine. Select the FLOOR mode and the lowest blower speed. Select the warmest temperature setting. Feel the temperature of the inlet and outlet heater hoses at the heater core. Is the inlet heater hose feel significantly hotter than the outlet heater hose? If yes, go to the next step. If no, go to step 17.
Replace the heater core. When the repair is completed, go to step 17.
Check for low engine temperature problems, Repair or replace as needed, go to step 17.
Operate the system in order to verify the repair. If the system operates properly, the repair is complete. If the heater still does not work properly, repeat the entire procedure.

Insufficient Defrosting

CAUTION
Check all fluid levels and adjust as needed, before operating vehicle for extended periods at idle.

Start the engine, select the DEFROST mode, and select the maximum blower speed. Does sufficient air flow from the defroster outlets? If yes, go to the next step. If there is insufficient airflow, go to step 9.
Measure the engine operating temperature. Does the engine reach normal operating temperature (approx. 200° F)? If yes, go to the next step. If the engine does not reach normal operating temperature, go to step 7.
Select the minimum blower speed. Select the warmest temperature setting. Carefully feel the inlet and outlet heater hoses at the heater core. Is the inlet heater hose significantly hotter than the outlet heater hose? If yes, go to step 10. If the hose temperature feels approx. the same, go to the next step.
Test the operation of the A/C compressor clutch. Does the A/C compressor clutch engage? If yes, go to step 6. If the compressor clutch does not engage, go to step 5.
Inspect A/C compressor clutch and controls. Repair or replace as needed, go to step 13.
Determine if the A/C system is operating within specifications. If yes, go to step 8. If no, go to step 11.
Check the low engine temperature problem. Repair any problems found, go to step 13.
Inspect for correct operation of the recirculation door. If the door is operating correctly, go to step 13. If the door is not operating properly, go to step 12.
Check air delivery system. Repair any problems found, go to step 13.
Check the heater core for blockage. Repair or replace as needed, go to step 13.
Check A/C performance. Repair or replace as needed, go to step 13.
Repair the recirculation door concern. When the repair is complete, go to step 13.
Operate the system in order to verify the repair. If the system is operating properly, the procedure is complete. If the system is still not providing proper defrosting, repeat the entire test.

Noise from Blower Motor

Inspect the air inlet grille for debris. If the grille has debris, go to step 7. If the grille is clear, go to the next step.
From inside the vehicle, close all vehicle doors and windows, turn ON the ignition, with the engine OFF, and cycle the blower motor through all speeds in order to determine where and when the noise occurs. If noise is heard during the blower operation, go to step 3. If there is no noise, go to step 10.
Inspect for excessive vibration at each blower motor speed by feeling the blower case. If there is vibration, go to step 5. If no vibration is present, go to the next step.
Listen to the blower motor at each blower speed. Is the blower motor making a squeaking or chirping noise? If yes, go to step 8. If no noise exists, go to step 10.
Remove the blower motor, and inspect the blower motor and impeller for deposits of foreign material. If there is debris, go to step 7. If there is no debris, go to the next step.
Inspect the blower motor impeller for cracked blades, loose impeller retainer, or improper impeller alignment. If any of these conditions exist, go to step 8. If none of these exist, go to step 9.
Remove the foreign material, go to step 10.
Repair or replace blower motor or impeller as needed, go to step 10.
Install the blower motor, go to step 10.
Operate the system in order to verify the repair. If the condition has been corrected, the repair is complete. If noise still exists, repeat the entire procedure.

Noise from A/C System

NOTE: Noise from the A/C system may be heard as squealing, chirping or moaning noises, or as a vibration noise.

Start the engine and verify operation of the A/C system. If a screeching or squealing noise heard when the A/C is engaged go to step 2. If not, go to step 8.
With engine OFF, inspect the drive belt for excessive wear. If the belt is excessively worn, go to step 17. If the belt is not worn, go to step 3.
Inspect the drive belt tension. If the tension is correct, go to step 4. If the tension is not correct, go to step 18.
Inspect the drive belt for excessive oil coverage. If the belt is covered with oil, go to step 16. If there is no oil present, go to next step.
Start the engine, ensure the A/C system is ON, and visually inspect the compressor and the clutch. If the compressor does not turn, go to step 23. If the compressor and clutch are visually okay, go to step 6.
Check compressor clutch for slippage, if the compressor is slipping, go to step 22. If the clutch is not slipping, go to step 7.
Using a stethoscope, listen to the A/C compressor for any abnormal noise. If noise appears to be caused by the compressor, go to step 14. If the compressor is not the cause of the noise, go to step 9.
Does a moaning noise exist when the A/C clutch is engaged? If yes, go to the next step. If not, go to step 11.
Listen to the A/C compressor components and mounting for noise concerns using a stethoscope. Are any of these components loose, damaged or excessively worn? If yes, go to step 19. If no, go to the next step.
Idle the engine and engage the A/C compressor clutch. Using a stethoscope, move around the entire refrigerant plumbing system. Listening for any abnormal noises caused by a component of the A/C system touching another component. Are any of the A/C components grounding out and causing a vibration noise? If yes, go to step 21. If no, go to step 12.
Does a vibration or rattle noise exist when the A/C clutch is engaged? If yes, go to the next step. If no, go to step 13.
Does the noise stop when the A/C clutch is disengaged? If yes, go to step 14. If no, go to step 24.
Idle the engine in PARK with the A/C compressor clutch engaged. Using a stethoscope, move around the entire A/C system testing for any abnormal noises caused by a component. Do any of the A/C components cause an abnormal noise? If yes, go to step 20. If no, go to step 24.
Verify that the A/C system is properly charged. If it is properly charged, go to step 23. If not properly charged, go to the next step.
Recharge the A/C system to specification. Is the abnormal compressor noise still present? If yes, go to step 23. If no, go to step 25.
Repair the oil leak. When the repair is complete, go to step 17.
Replace the drive belt. When the repair is complete, go to step 25.
Replace the drive belt tensioner or adjust drive belt tension. When the repair is complete, go to step 25.
Repair or replace the A/C compressor mounting component. When the repair is complete, go to step 25.
Repair or replace the component that is causing the moaning concern as needed. When the repair is complete, go to step 25.
Correctly route or insulate the A/C component. When the repair is complete, go to step 25.
Verify A/C system is not overcharged. Replace the A/C compressor clutch. When the repair is complete, go to step 25.
Inspect the A/C compressor. Repair or replace as needed. When the repair is complete, go to step 25.
The concern may be caused by an engine related component. If the concern is found and repaired, go to step 25.
Operate the system in order to verify the repair. If the system is okay, the repair is complete. If not, repeat the entire procedure.

Noise from the HVAC Housing (Evaporator Case)

Start the engine. Cycle through all blower speeds, A/C mode settings and temperature control settings. Determine the type of noise, whether it is a scraping, popping, ticking, clicking, chirping or groaning, or an air rush or whistle. Is a scrape or pop noise evident when selecting modes or temperature settings? If yes, go to step 5. If no, go to the next step.
Is a tick/click, chirping, groaning or scraping noise present, but decreases as blower motor speed is decreased? If yes, go to step 5. If no, go to the next step.
Is an air rush/whistle noise evident in all modes but not all temperature settings? If yes, go to step 5. If no, go to the next step.
Is an air rush/whistle noise evident only in defrost or floor mode? If yes, go to step 5. If no, examine for other sounds, repeat step 1.
Remove components as needed to access the HVAC module. When complete, go to the next step.
Inspect the airflow doors for proper operation and the ducts for obstructions or foreign materials. Were any of these conditions found? If yes, go to step 9. If no, go to the next step.
Inspect the mode and temperature doors and seals for warping or cracking. Are the doors in normal condition? If yes, go to step 9. If no, go to the next step.
Replace the appropriate door and/or seals. When the repair is complete, go to step 10.
Remove any obstructions or foreign material found. When the repair is complete, go to step 10.
Install the components removed in step 5. When complete, go to the next step.
Operate the system to verify the repair. If system operates without noise, the repair is complete. If noise still exists, repeat the entire procedure.