HVAC System: Other Mercury Sable IV

Heating and Ventilation

The heating and ventilation system operates as follows

1. Controls the temperature and during climate control operation, reduces the relative humidity of the air inside the vehicle.
2. Delivers heated or cooled air to maintain the vehicle interior temperature and comfort level.
3. The blower motor (19805) draws either outside or inside air through the A/C recirculating air duct (19C590) from just below the windshield depending on the function selector switch position.
4. All airflow from the blower motor passes through the A/C evaporator core (19860).
5. The temperature is then regulated by reheating a portion of the air and blending it with the remaining cool air to the desired temperature.
6. The temperature blending is varied by the temperature blend door, which regulates the amount of air that flows through and around the heater core (18476), where it is then mixed and distributed.

Heater Core and Evaporator Core Housing

The heater core and evaporator core housing is located behind the instrument panel (04320) between the recirculating air duct and heater air plenum chamber (18471).

Torque Specifications

The A/C evaporator housing assembly contains the following major components

1. A/C evaporator core
2. heater core
3. air distribution doors

Heater Core

The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer it to air passing through the heater core.

Blower Motor

The blower motor pulls air from the A/C recirculating air duct and forces it into the A/C evaporator housing where it is mixed and distributed.

Heater Hoses

The heater hoses are made of rubber hose and metal tube assemblies that are connected together using aluminum clamps that are crimped into place. The aluminum clamps must not be removed. The heater hoses must not be serviced as subassemblies by separating the rubber hoses from the metal tubes. On vehicles equipped with a 3.0L (2V) engine, the heater core inlet hose and the heater core outlet hose are two separate assemblies. On vehicles equipped with a 3.0L (4V) engine, the heater core inlet hose and heater core outlet hose are a single assembly and should be serviced as a single assembly.

Refer to CLIMATE CONTROL SYSTEM GENERAL INFORMATION .

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1. Remove pin-type retainers and the right instrument panel insulator.
2. Remove the blower motor (19805). Disconnect the electrical connector Remove the screws and remove the blower motor.
3. To install, reverse the removal procedure.

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1. Prepare the vehicle for heater core and evaporator core housing removal. Recover the refrigerant. Refer to «CLIMATE CONTROL SYSTEM GENERAL INFORMATION»(ref-178710) . Remove the instrument panel.
2. Remove the right side cowl vent screen (018A16).
3. Remove the screw's and the water shield.
4. Disconnect the vacuum supply hose.
5. Using suitable hose pinching pliers, clamp the heater hoses. Disconnect the heater hoses. Cap the heater core tubes.
6. Disconnect the evaporator outlet spring lock coupling and cap the evaporator outlet tube and the suction accumulator tube. For additional information on spring lock couplings, refer to «SPRING LOCK COUPLING»(ref-178710-S38808236292005062100000) . During installation, install new O-ring seals lubricated with PAG oil or equivalent.
7. Remove the two bolts.
8. Disconnect the evaporator inlet spring lock coupling and cap the evaporator inlet tube and the condenser to evaporator line tube. For additional information on spring lock couplings, refer to «SPRING LOCK COUPLING»(ref-178710-S38808236292005062100000) . During installation, install new O-ring seals lubricated with PAG oil or equivalent.
9. Remove the three nuts at the dash panel.
10. Remove the screws and the heater outlet floor duct.
11. Remove the bolt and nut.
12. Remove the heater core and evaporator core housing (19B555).
13. To install, reverse the removal procedure. Lubricant the coolant hoses with coolant hose lubricant or plain water only, if needed.
14. Evacuate, leak test and charge the A/C system. Refer to «CLIMATE CONTROL SYSTEM GENERAL INFORMATION»(ref-178710) .
15. Refill the cooling system. Refer to ENGINE COOLING .

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