How to remove the heater core on 94 mercury - Mercury Cars & Trucks

Removing the Old Core

• Disconnect the Mercury Cougar's negative battery cable. Remove the center console from the interior. Disarm the car's air bag system and remove the bag's diagnostic monitor and bracket.
  

• Take the heater outlet floor duct out of the car. Remove the screw holding the air transfer duct and push it into the outlet duct. Unscrew the screws retaining the outlet duct to the heater core cover and release the retaining tabs on each side to remove the duct.
  

• Raise and support the Mercury Cougar, using multiple jackstands. Drain the engine coolant by removing the drain plug on the bottom of the radiator. Replace the drain plug after all the liquid flows into a clean container and disconnect the heater hoses from the core
  

• Withdraw the black vacuum supply hose from the vacuum source (you can now lower the vehicle). Disconnect the same hose from the air conditioner's vacuum reservoir tank.
  

• Detach the heater core cover that holds the core by releasing the retaining tabs and removing the clips. Remove the dash panel seal, vacuum hose and heater core bracket from the cover.
  

• Remove the heater core from the cover and the case seal from the core
  

2 days and some help.
http://www.autozone.com/repairguides/2005-Mercury-Monterey/Heater-Core/Removal-Installation/_/P-0996b43f80f65b7c

yes you must remove the whole dash and consoul

Check your coolant level. If the coolant is low it won't pass through the heater core, therefore you get no heat. The overflow bottle really isn't an accurate way to check the level, actually remove the radiator cap and look in there. You should be able to see the coolant near the top. BE SURE THE ENGINE IS COLD BEFORE YOU REMOVE THE RADIATOR CAP!!!

Check the fuses. My heater went out so I changed the fuses and it works perfectly now!

remove dash

you have to remove the plenum case behind the dash. I will provide 94 gr marquis. don't have 84.



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Section 12-03A: Air Conditioning System—Manual A/C-Heater 1994 Crown Victoria/Grand Marquis. Workshop Manual
REMOVAL AND INSTALLATION Heater Core Removal

1. Remove the heater air plenum chamber assembly as outlined.
2. Heater Air Plenum Chamber Removal
   
   1. Disconnect battery ground cable .
   1. Disconnect the heater water hoses from the heater core tubes. Plug the ends of the heater water hoses to prevent coolant loss.
   1. Plug heater core tubes securely to prevent coolant leakage from heater core during heater air plenum chamber removal.
   1. Remove three nuts located below the windshield wiper motor (17508) retaining the LH end of the heater air plenum chamber to the dash panel .
   1. Remove one nut retaining the upper LH corner of the A/C evaporator core housing to the dash panel .
   1. Remove LH and RH lower instrument panel insulators.
   1. Disconnect two vacuum supply hoses from vacuum source. Push grommet and vacuum supply hose into passenger compartment.
   1. Remove all instrument panel retaining screws and pull the instrument panel back as far as possible without disconnecting any wire harnesses.
   1. Loosen the RH door sill plate and remove the RH side cowl trim panel.
   1. Remove cross body brace and disconnect wiring harness from A/C electronic door actuator motor (19E616) and disconnect the sensor tube from the evaporator case connector.
   1. Disconnect the vacuum jumper harness at the multiple vacuum connector near the heater outlet floor duct.
   1. Disconnect the white vacuum hose from the heater and A/C air inlet duct door vacuum control motor.
   1. Remove two hush panels.
   1. Remove one plastic push fastener retaining the heater outlet floor duct to the LH end of the heater air plenum chamber . Remove LH screw and loosen RH screw on the rear face of the heater air plenum chamber and remove the heater outlet floor duct .
   1. Remove two nuts from the two studs along the lower flange of the heater air plenum chamber .
   1. Carefully move heater air plenum chamber rearward to allow heater core tubes and the stud at the top of the heater air plenum chamber to clear holes in the dash panel. Remove heater air plenum chamber from vehicle by rotating the top of the heater air plenum chamber forward, down and out from under the instrument panel . Carefully pull lower edge of instrument panel rearward as necessary while rolling the heater air plenum chamber from behind the instrument panel .

1. Remove the four retaining screws from the heater core cover (18B300) and remove the heater core cover from the heater air plenum chamber assembly.
   
   Heater Core Removal
   
   
   
   
   
   Item Part Number Description 1 390092-S2 Screw (2 Req'd) 2 18658 Heater Core Case Seal 3 18476 Heater Core 4 18570 Heater Dash Gasket 5 18471 Heater Air Plenum Chamber 6 18B300 Heater Core Cover

1. Pull the heater core assembly from the heater air plenum chamber assembly.

Installation

1. Carefully install heater air plenum chamber assembly into the heater air plenum chamber assembly. Visually check to ensure that core seal is properly positioned.

1. Position the heater core cover and install the four retaining screws.

1. Install the heater air plenum chamber assembly as outlined.

1. Disconnect battery ground cable.
2. Remove glove box attaching screws, then the glove box.
3. Remove lower sound insulator attaching screws and nuts, then the lower sound insulator.

Heater And A/C Programmer And Actuators

1. Remove programmer as follows:

1. Remove programmer shield attaching screws, then the programmer shield.
2. Disconnect threaded rod from programmer.
3. Disconnect programmer electrical and vacuum connector, then remove programmer.

1. Disconnect body control module electrical connector, then remove module attaching screws and module.
2. Remove relay panel from module assembly, then the module assembly heater core cover.
3. Disconnect heater hoses from heater core.
4. Remove two heater core attaching screws, then the heater core.
5. Reverse procedure to install.

Sounds like the heater core is stopped up. Try removing the heater hoses and backflushing the core.If this doesn't work replace the core.

This is a big job which involves discharging and removing parts of the A/C system as well as removing parts of the dash. I had the core done on a 94 Sable years ago and it was a very labor intensive and expensive job. Here are some instructions I found for a 94 Taurus which should be the same thing or similiar, but I don't guarantee that. Please note that these instructions were not tested by me and may contain errors or be incomplete in some way. For example "remove instrument panel" sounds simple but in reality is a process in itself requiring the removal of many screws. Naturally you would have to recharge the A/C and refill the coolant when done.
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Removal

1. Remove instrument panel and lay it on front seat.
2. Remove A/C evaporator housing as outlined.
3. Remove vacuum source line from heater dash panel seal (18529).
4. Remove heater dash panel seal from heater core tubes (refer to Heater Case Assembly).
5. Remove four heater core access cover retaining screws and remove heater core cover (18B300) from A/C evaporator housing.
6. Lift heater core and seals from A/C evaporator housing.
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Installation

1. Transfer three foam core seals to new heater core.
2. Install heater core and seals into A/C evaporator housing.
3. Position heater core cover on A/C evaporator housing. Install four retaining screws.
4. Install heater dash panel seal on heater core tubes.
5. Install vacuum source line through heater dash panel seal.
6. Install A/C evaporator housing into vehicle as outlined.
7. Reinstall dashboard components.

Best of Luck!

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