AC Hose - High Side

Replace the high-pressure AC hose connecting the compressor to the condenser on a 1970 AMC Rebel Machine with 390ci V8 engine.

Warnings

Tools required

Parts

• AC high-side hose assembly × 1 — Use OEM specification or equivalent for R-12 system
• AC line O-rings × 4 — Size specific to compressor and condenser fittings
• R-12 refrigerant or R-12 substitute × 1 — Quantity per system capacity, typically 2-3 lbs

Preparation

1. Verify AC system has not been operated for at least 30 minutes to allow pressure equalization and cooling
2. Position vehicle on level surface and engage parking brake
3. Open hood and secure in upright position
4. Locate AC compressor on passenger side of engine and trace high-side hose from compressor to condenser at front of radiator
5. Place drip pan beneath work area to catch any residual refrigerant oil

Procedure

1. 1

   Recover refrigerant from system
   Connect AC recovery machine to service ports on the system. Follow recovery machine manufacturer instructions to completely evacuate all refrigerant from the system. Note the amount of refrigerant recovered for recharging reference. Allow system to stabilize and verify no pressure remains on gauges.
2. 2

   Disconnect high-side hose at compressor
   Locate the high-side discharge fitting on the rear of the AC compressor (typically the smaller of two lines). Using a line wrench on the hose fitting and a backup wrench on the compressor port, loosen the connection slowly to release any residual pressure. Once depressurized, remove the hose fitting completely. Cap the compressor port immediately with a clean plug to prevent contamination.
3. 3

   Remove hose bracket fasteners
   The high-side hose is typically secured with one or two metal brackets along the inner fender or firewall near the compressor. Remove the bolts or screws securing these brackets. Note the routing and position of any clips or supports for reinstallation.
4. 4

   Disconnect high-side hose at condenser
   Access the condenser inlet fitting at the top driver side of the condenser assembly in front of the radiator. Using a line wrench, disconnect the high-side hose from the condenser inlet. The fitting may be tight due to age and corrosion. Apply penetrating oil if necessary and allow time to soak. Remove hose from vehicle.
5. 5

   Inspect fittings and ports
   Examine the compressor discharge port and condenser inlet port for damage, corrosion, or debris. Clean threads with a wire brush if necessary. Inspect the condition of O-ring sealing surfaces - they should be smooth without gouges or scratches. Check that the new hose has correct fittings that match the original configuration.
6. 6

   Prepare new high-side hose
   Install new O-rings on both ends of the replacement hose. Lightly coat O-rings with appropriate refrigerant oil (mineral oil for R-12 systems, PAG oil if converting to R-134a). Ensure O-rings are seated properly in their grooves on the hose fittings.
7. 7

   Install hose at condenser
   Route the new high-side hose from the compressor area to the condenser, following the original path. Thread the hose fitting onto the condenser inlet by hand until snug. Using a line wrench and backup wrench, tighten the connection firmly - typically 15-20 ft-lbs for flare fittings, but avoid over-tightening which can damage the flare seat.
8. 8

   Secure hose brackets
   Position the hose in its support brackets along the routing path. Install and tighten bracket bolts or screws to secure the hose. Ensure the hose has no sharp bends, does not contact moving parts or hot exhaust components, and has adequate clearance from the serpentine belt and pulleys.
9. 9

   Connect hose at compressor
   Remove the protective cap from the compressor discharge port. Thread the hose fitting onto the compressor port by hand until snug. Using a line wrench on the hose fitting and backup wrench on the compressor port, tighten the connection firmly - typically 15-20 ft-lbs. Do not over-tighten as this can damage the O-ring seal.
10. 10

    Evacuate AC system
    Connect vacuum pump to AC service ports using manifold gauge set. Evacuate the system to at least 29 inches of vacuum. Maintain vacuum for minimum 30-45 minutes to remove all air and moisture from the system. Close valves and monitor vacuum gauge for 10 minutes to verify system holds vacuum without leak.
11. 11

    Recharge AC system
    With system under vacuum, connect refrigerant supply (R-12 or approved substitute matching system specifications). Charge system to proper capacity based on recovered amount or factory specifications (typically 2.5-3.0 lbs for this vehicle). Monitor pressures on manifold gauges during charging. Start engine and engage AC to draw in full charge under operating conditions.

Reassembly

1. Verify all hose connections are tight and properly secured in brackets
2. Confirm hose routing does not interfere with any moving components or contact hot surfaces
3. Check that proper refrigerant capacity has been achieved per factory specifications

Verification

• Start engine and allow to reach normal operating temperature
• Turn AC to maximum cold and high blower speed
• Verify compressor clutch engages and system operates smoothly without unusual noises
• Check that high-side line becomes hot to the touch near compressor (150-250 psi typical operating pressure)
• Inspect all connections for signs of refrigerant oil leakage while system is operating
• Use leak detector or soap solution on all fittings to verify no refrigerant leaks are present
• Confirm cold air discharge from vents reaches acceptable temperature (typically 40-50°F at vent)

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