Remove and replace the AC evaporator core in a 1966 Chevrolet Corvette with 327ci V8, requiring complete dash disassembly and refrigerant system evacuation.

Warnings

Tools required

Parts

• AC evaporator core × 1 — Use OEM specification or aftermarket equivalent for 1966 Corvette
• Evaporator case gasket/seal kit × 1 — Use OEM specification
• AC O-ring kit × 1 — Use appropriate size for refrigerant fittings
• AC refrigerant oil × 1 — Mineral oil for R-12 or PAG oil for R-134a retrofit
• Expansion valve (if worn or contaminated) × 1 — Use OEM specification
• Receiver-drier × 1 — Replace whenever system is opened
• Dashboard pad clips (replacement as needed) × 1 — Various GM clips

Fluids

• AC refrigerant R-12 or R-134a (if retrofitted)

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Allow engine to cool completely if recently operated
4. Have AC system professionally evacuated and refrigerant recovered by certified technician
5. Place protective covers over seats and interior to prevent damage during extensive dash work
6. Drain cooling system sufficiently to work below heater core level
7. Remove both seat assemblies for better access and working room
8. Photograph all electrical connections, vacuum lines, and cable routing before disassembly

Procedure

1. 1

   Disconnect refrigerant lines at firewall
   Disconnect the liquid line and suction line at the firewall fittings where they connect to the evaporator, using flare nut wrenches or appropriate fitting wrenches as required by the factory Harrison connection type. Cap all open refrigerant ports immediately with plugs or tape to prevent moisture and contamination entry. Remove the 2 mounting nuts securing the refrigerant line bracket to the firewall.
2. 2

   Disconnect heater hoses
   Place drain pan under engine side of firewall. Loosen hose clamps and disconnect both heater hoses from the heater core tubes at the firewall. Allow coolant to drain into pan. Cap or plug heater core tubes to prevent further drainage.
3. 3

   Remove center console and radio assembly
   Remove the center console mounting screws (typically 4 along bottom edge). Disconnect shift indicator cable at the console shifter quadrant if equipped with Powerglide automatic transmission. Lift console up and rearward to remove. Remove radio knobs by pulling straight off. Remove radio bezel retaining nuts behind knobs. Disconnect antenna cable and power/speaker leads from radio. Remove radio from dash opening. Label all electrical connections during removal.
4. 4

   Remove instrument cluster
   Remove the 6 screws securing instrument cluster bezel. Carefully pull cluster forward. Disconnect speedometer cable by pressing tab and pulling straight back. Disconnect all electrical connectors from gauges, noting wire colors and positions. Remove cluster assembly from dash. Support carefully to avoid damaging gauge faces.
5. 5

   Disconnect control cables and wiring
   Disconnect heater control cables at the heater box by removing cable retaining clips. Disconnect temperature control cable, mode control cable, and fresh air door cable. Disconnect all electrical connectors for AC switch, blower motor resistor, and blower motor. Label each cable and wire for correct reassembly. Disconnect vacuum lines from climate control head unit and label each line.
6. 6

   Remove steering column lower cover and drop column
   Remove steering column lower trim cover screws. Note: the 1966 Corvette uses a console-mounted floor shifter; there is no column-mounted shift indicator cable to disconnect on this platform. Remove the 2 nuts securing steering column bracket to underside of dash support. Carefully lower steering column and rest on driver's seat (use padding to protect seat). Do not disconnect steering shaft from gearbox.
7. 7

   Remove lower dash panels and kick panels
   Remove lower instrument panel covers on both driver and passenger sides by removing retaining screws. Remove both kick panels by removing screws and carefully prying trim clips. Remove lower center dash panel below radio area. This provides access to upper dash mounting points and heater/evaporator assembly.
8. 8

   Disconnect and remove upper dash assembly
   Remove the upper dash pad by removing the retaining screws along windshield edge (typically 8-10 screws) and pulling clips at rear edge. Remove remaining dash-to-cowl mounting bolts, typically 4-6 bolts accessible from underside after lower panels are removed. Disconnect remaining electrical connectors, vacuum lines, and ensure no cables remain attached. Carefully withdraw entire dash assembly rearward with assistance—this is a large, awkward component.
9. 9

   Access and remove evaporator case assembly
   With dash removed, the heater/evaporator case assembly is now visible mounted to the firewall. Remove the blower motor assembly by disconnecting wiring and removing the 3 mounting screws. Remove all remaining nuts and bolts securing the evaporator case to the firewall (typically 6-8 nuts on studs protruding through firewall). Carefully pull entire case assembly away from firewall and remove from vehicle.
10. 10

    Disassemble evaporator case
    Place evaporator case on clean workbench. Remove the case retaining screws (typically 8-12 screws around perimeter of case halves). Carefully separate case halves. Note position of foam seals, air doors, and ductwork routing. Remove expansion valve from evaporator inlet by removing 2 bolts. Carefully lift evaporator core from case, noting orientation of inlet/outlet tubes.
11. 11

    Install new evaporator core
    Clean evaporator case halves thoroughly, removing all old sealant and debris. Install new foam seals in case as required. Lubricate new O-rings with AC system oil and install on evaporator inlet and outlet tubes. Position new evaporator core in case lower half with tubes oriented correctly toward firewall openings. Install expansion valve with new O-rings to evaporator inlet. Verify all air door linkages move freely.
12. 12

    Reassemble and reinstall evaporator case
    Apply thin bead of weatherstrip adhesive to case mating surfaces if needed. Join case halves and install all perimeter screws, tightening in cross pattern for even seal compression. Reinstall blower motor assembly with 3 mounting screws. Position evaporator case assembly to firewall, aligning mounting studs through firewall holes. Install and tighten all case-to-firewall mounting nuts from inside vehicle.
13. 13

    Reconnect refrigerant lines and heater hoses
    Remove caps from evaporator tubes and refrigerant lines. Install new O-rings lubricated with AC oil on all refrigerant fittings. Connect liquid line and suction line to evaporator tubes at firewall using flare nut wrenches. Tighten fittings securely but do not overtighten aluminum threads. Install refrigerant line bracket with 2 mounting nuts. Connect heater hoses to heater core tubes and secure with new hose clamps.
14. 14

    Reinstall dashboard assembly
    With assistance, carefully position dashboard assembly back into vehicle, guiding it over steering column opening. Align dash mounting holes with cowl studs and brackets. Install all dash-to-cowl mounting bolts and tighten securely. Reconnect all electrical connectors, vacuum lines, and control cables using photos and labels from disassembly. Reinstall upper dash pad with all retaining screws and clips.
15. 15

    Reinstall steering column and interior components
    Raise steering column into position and install 2 mounting nuts to dash bracket. Reconnect shift indicator cable if automatic. Install steering column lower cover. Reinstall lower dash panels and kick panels with all screws and clips. Reinstall instrument cluster, connecting all gauge wiring and speedometer cable. Install cluster bezel with 6 screws. Reinstall radio with all connections and bezel. Reinstall center console with mounting screws. Reinstall both seats.
16. 16

    System evacuation and recharge
    Reconnect battery negative cable. Refill cooling system with conventional ethylene glycol (green) coolant mixed 50/50 with water to proper level. Have AC system professionally evacuated to at least 29 inches Hg vacuum for a minimum of 30-45 minutes to remove all moisture. Install the new receiver-drier before evacuation. After the system holds vacuum, recharge with the appropriate refrigerant type (R-12 original or R-134a if retrofitted) and correct oil quantity per system specifications.

Reassembly

1. Verify all dashboard screws, clips, and fasteners are reinstalled—keep small parts organized during disassembly
2. Ensure all control cables operate smoothly through full range before final dash installation
3. Check that no electrical connectors, vacuum lines, or ground straps were missed before closing up interior
4. Torque all refrigerant fittings carefully—aluminum threads strip easily with excessive force

Verification

• Start engine and verify all dashboard gauges, lights, and switches function correctly
• Operate heater and AC controls through all modes and temperature settings, verifying proper air flow and door operation
• Check for refrigerant leaks at all AC fittings using electronic leak detector or soap solution
• Verify AC system produces cold air with center vent temperatures below 45°F at idle
• Check coolant level after engine reaches operating temperature and top off if needed
• Inspect for any coolant or refrigerant leaks at firewall penetrations
• Verify steering column operates normally with no binding or interference
• Test drive vehicle to ensure all controls remain functional and no rattles or squeaks developed

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