Here's a breakdown of the difficulty and the repair process:
Difficulty Factors:
* Accessibility: The heater core is located deep within the dashboard, behind the instrument panel. Reaching it requires removing a significant portion of the dash, often involving removing steering column components, the radio, and various other trim pieces.
* Complexity: The disassembly process is intricate and requires careful attention to detail. You'll need to disconnect numerous electrical connectors, hoses, and potentially even the HVAC control system. Incorrect reassembly can lead to problems with the climate control system.
* Potential for Damage: There's a risk of damaging fragile plastic components during disassembly, especially if you're not familiar with the vehicle's interior structure.
* Cooling System Flush: After replacement, you'll need to thoroughly flush the cooling system to remove any debris that may have entered during the repair.
Fixing the Steam Problem (Heater Core Replacement):
Since it's blowing steam even with the heat off, it indicates a leak in the heater core. The only reliable fix is replacement. Here's a general outline; always consult a repair manual specific to your 1986 Thunderbird for detailed instructions and diagrams. Improper repair can lead to further damage or injury.
1. Gather Tools and Parts: You'll need a complete set of metric sockets, screwdrivers, pliers, wrenches, a coolant recovery system, a new heater core (ensure it's the correct one for your vehicle), new hoses (if needed), and possibly new O-rings and seals. A repair manual is essential.
2. Disconnect the Battery: This is crucial to prevent accidental short circuits.
3. Drain the Cooling System: Completely drain the coolant from the engine and radiator.
4. Dash Disassembly: This is the most challenging part. You'll likely need to remove:
* Steering column components (partially or fully, depending on access)
* Instrument panel (potentially)
* Radio and other dash components
* HVAC system components
* Glove box
* Various trim pieces
5. Access the Heater Core: Once the dashboard is sufficiently disassembled, you'll locate the heater core.
6. Disconnect the Heater Core Hoses: Carefully disconnect the coolant hoses connected to the heater core. Have a container ready to catch any remaining coolant.
7. Remove the Heater Core: This can be tricky; some designs require removing the entire HVAC housing.
8. Install the New Heater Core: Carefully install the new heater core, ensuring proper seating and connections.
9. Reconnect the Hoses: Reconnect the coolant hoses securely, paying close attention to hose clamps.
10. Reassemble the Dashboard: Reverse the disassembly process, carefully connecting all electrical connectors and securing all components.
11. Fill and Bleed the Cooling System: Fill the cooling system with the correct coolant mixture and bleed the system to remove any air pockets.
12. Test the System: Start the engine and test the heater to ensure it works correctly and there are no leaks.
Alternatives (Not Recommended for a Persistent Leak):
* Sealant: While some people try using sealants to patch a leaking heater core, this is generally a temporary and unreliable solution. It often fails and can lead to bigger problems down the road.
Recommendation:
Unless you have extensive automotive experience and access to a detailed repair manual with diagrams for your specific Thunderbird model, it's strongly recommended to take your car to a qualified mechanic for this repair. The complexity of the job, potential for damage, and the risk of incorrect reassembly make it a task best left to professionals. The cost of professional repair may be less than the cost of damaged parts and time spent if something goes wrong during a DIY attempt.
