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Home >> Cadillac >> 2000 >> Seville SLS >> Repair and Diagnosis >> External Pages >> Different car >> Section 27 (HVAC Systems - Automatic) >> Performance Tests >> Heater System

Heater System

WARNING: This page is about a different car, the 2002 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.
  1. Were you sent here from TOO COLD IN VEHICLE? If so, go to next step. If not, see TEST M: TOO COLD IN VEHICLE  under SYMPTOM TESTS.
  2. Start the engine. Allow the engine to idle. Does the engine reach a normal operating temperature? If so, go to next step. If not, go to step  9.
  3. Allow to idle. Select the FLOOR mode. Select the minimum blower speed. Select the maximum temperature setting. Feel the temperature of the inlet and outlet hoses at the heater core. Does the inlet hose feel warmer than the outlet hose? If so, go to step  7. If not, go to next step.
  4. Install a thermometer into the I/P center air outlet. Secure a thermometer to the heater core outlet hose. Select the panel outlets. Select the maximum blower speed. Select the maximum temperature setting. Record the temperature at the center air outlet and heater core outlet hose. Compare the recorded temperatures. Are the temperatures similar? If so, go to next step. If not, go to step  6.
  5. Check the following areas of the vehicle for cold air leaks: The cowl, recirculation door and HVAC module case. Perform the necessary repairs. After repairs are completed, go to step  10.
  6. Inspect the temperature door operation. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. Perform any necessary repairs. After repairs are completed, go to step  10.
  7. Turn the engine off. Backflush the heater core. Start the engine. Select the FLOOR mode. Select the minimum blower speed. Select the maximum temperature setting. Feel the temperature of the inlet and outlet hoses at the heater core. Does the inlet hose feel warmer than the outlet hose? If so, go to next step. If not, go to step  10.
  8. Replace the heater core. See HEATER CORE  under REMOVAL & INSTALLATION. After repairs are completed, go to step  10.
  9. Repair the low engine temperature concern. Check thermostat and cooling fan operation. After repairs are completed, go to next step.
  10. Operate the system in order to verify the repair. Does the system operate correctly? If so, system is okay. If not, go to step  2.
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