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AT AT AT AT Air Air Air Air Conditioner Conditioner Conditioner Conditioner - 176 - Diagnosis Diagnosis Diagnosis Diagnosis and and and and Testing Testing Testing Testing A/C A/C A/C A/C system system system system performance performance performance performance diagnosis diagnosis diagnosis diagnosis 1. Air heater performance diagnosis. Step Operation Yes No 1 Whether or not to conduct this diagnosis based on “ symptoms ” or Go to Step 2. — 2 ①Start the engine. ②Let the engine idling. Does the engine temperature reach normal operating temperature? Go to Step 3. Go to Step 9. 3 ①Let the engine idling. ②Select “FLOOR” mode. ③Set the minimum speed of blower. ④Set the warmest temperature. ⑤Sense the temperature of inlet and outlet hoses at the heater core. Is the inlet hose of heater warmer than the outlet hose? Go to Step 7. Go to Step 4. 4 ①Place the temperature gauge at the central air vent. ②Fix the temperature gauge onto the outlet hose at the heater core. ③Set the maximum speed of blower. ④Set the warmest temperature. ⑤Record temperature at the position listed below: Central air vent on instrument panel. Outlet hose at the heater core. ⑥Compare the recorded temperatures. Are these two temperatures nearly the same? Go to Step 5. Go to Step 6. 5 ①Check the following parts of vehicle for cold air leak and conduct relevant maintenance: Front shield plate. Internal circulation damper. Air heater, ventilation and A/C system module housing. ②Conduct necessary maintenance. Is the maintenance finished? Go to Step 10. — 6 ①Check the operation of temperature damper. ②Conduct necessary maintenance. Is the maintenance finished? Go to Step 10. — 7 ①Shut down the engine. ②Backflush the heater core. ③Start the engine. ④Select “FLOOR” mode. ⑤Set the minimum speed of blower. ⑥Set the warmest temperature. ⑦Sense the temperature of inlet and outlet hoses at the heater core. Is the inlet hose of heater warmer than the outlet hose? Go to Step 8. Go to Step 10. 8 Replace the heater core. Is the maintenance finished? Go to Step 10. — 9 Troubleshoot too low engine temperature. Is the maintenance finished? Go to Step 10. —
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