AC Hose Assembly

Remove and replace the AC hose assembly on a 1970 AMC Rebel Machine with 390ci V8, including discharge, hose removal, installation, and recharge of the system.

Warnings

Tools required

Parts

• AC hose assembly × 1 — Use OEM specification or AC Delco equivalent for 1970 AMC
• AC O-ring kit × 1 — Use OEM specification
• R-12 refrigerant or R-12 replacement × 1 — Verify system compatibility before use
• PAG oil or mineral oil × 1 — Based on refrigerant type used

Preparation

1. Verify AC system refrigerant type (R-12 original or converted to R-134a or other)
2. Park vehicle on level surface and engage parking brake
3. Allow engine to cool completely before beginning work
4. Locate AC hose routing - typically runs from compressor on driver side to firewall connections
5. Ensure AC recovery equipment is certified and operational
6. Prepare new hose assembly by inspecting for damage and coating new O-rings with appropriate AC oil

Procedure

1. 1

   Recover refrigerant from system
   Connect AC manifold gauge set to service ports (low side on accumulator, high side near compressor). Connect recovery machine and fully recover all refrigerant from the system according to EPA regulations and equipment manufacturer instructions. Verify system pressure reaches 0 PSI on both gauges before proceeding.
2. 2

   Identify hose routing and connections
   Trace the AC hose assembly to identify all connection points. The 1970 Rebel typically has hoses running from compressor (mounted low on driver side of engine) to condenser (front of radiator) and through firewall to evaporator. Take photos of routing for reference during reinstallation.
3. 3

   Disconnect hose at compressor
   Using flare nut wrench to prevent fitting damage, loosen and remove the AC hose connection at the compressor. Immediately cap the open compressor port with plugs or tape to prevent moisture and debris entry. Remove and discard old O-rings from fitting.
4. 4

   Disconnect hose at condenser or evaporator
   Locate the opposite end of the failed hose assembly at either the condenser (in front of radiator) or evaporator connection (at firewall). Use flare nut wrench to disconnect the fitting. Cap the open port immediately. If hose passes through brackets or clips, note locations and remove fasteners.
5. 5

   Remove old hose assembly
   Carefully extract the old hose assembly from engine bay, noting routing around belts, pulleys, and hot engine components. Remove any mounting brackets or clips securing the hose. Inspect removed hose for failure point to confirm diagnosis.
6. 6

   Inspect system components
   With hoses removed, inspect all exposed fittings, ports, and O-ring sealing surfaces for damage, corrosion, or debris. Clean fitting surfaces with lint-free cloth. Check compressor shaft seal for oil leakage. If metal debris or contamination is present, system may require flushing.
7. 7

   Install new O-rings
   Install new O-rings on all fittings where hose will connect. Coat O-rings liberally with appropriate AC system oil (mineral oil for R-12, PAG oil for R-134a conversions). Ensure O-rings are properly seated in grooves and not twisted or damaged.
8. 8

   Route new hose assembly
   Route new AC hose assembly through engine bay following original path documented earlier. Ensure hose does not contact exhaust manifolds, sharp edges, or moving components. The hose should have adequate clearance from belts and pulleys. Reinstall any mounting brackets or clips.
9. 9

   Connect hose to compressor
   Remove cap from compressor port. Thread the hose fitting onto compressor by hand until firmly seated, then tighten with flare nut wrench. Tighten securely but do not over-torque aluminum fittings. Connection should be snug without excessive force.
10. 10

    Connect hose at opposite end
    Remove cap from condenser or evaporator port. Connect the opposite end of hose assembly, hand-threading first and then tightening with flare nut wrench. Verify all connections are secure and hose routing has not shifted during final tightening.
11. 11

    Evacuate system
    Connect vacuum pump to AC system via manifold gauge set. Evacuate system to minimum 29 inches of mercury vacuum for at least 30 minutes (45 minutes recommended for this older system). Close valves and observe vacuum hold for 10 minutes - significant vacuum loss indicates a leak that must be repaired.
12. 12

    Recharge AC system
    With system holding vacuum, recharge with appropriate refrigerant type to original specification (typically 2.5-3.0 lbs for 1970 AMC systems - verify on underhood label or service manual). Add refrigerant slowly through low-side port with engine running and AC on maximum. Monitor gauge pressures during charging.

Reassembly

1. Verify all AC hose connections are tight and properly routed away from heat and moving parts
2. Ensure all mounting brackets and clips are reinstalled to prevent hose vibration
3. Check that no tools or caps were left in engine bay

Verification

• Start engine and run AC system on maximum cold setting for 10 minutes
• Use leak detector to check all new connections for refrigerant leaks
• Verify system pressures are within specification (approximately 25-45 PSI low side, 200-250 PSI high side at idle with ambient temperature around 75-80°F)
• Confirm cold air output from dash vents reaches at least 40°F below ambient temperature
• Inspect hose routing with engine running to ensure no contact with moving components or excessive vibration
• Recheck all connections after initial test run for any seepage or oil residue

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