Mitsubishi Pick-ups and Montero 1983-1995 Repair Guide

Refrigerant Lines



See Figures 1, 2, 3 and 4

Kinks in the refrigerant tubing or sharp bends in the refrigerant hose lines will greatly reduce the capacity of the entire system. High pressures are produced in the system when it is operating. Extreme care must be exercised to make sure that all connections are pressure tight. Dirt and moisture can enter the system when it is opened for repair or replacement of lines or components. The following precautions must be observed.

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Fig. Fig. 1: The two types of refrigerant line fittings and the correct installation of new O-rings-all models

The system must be completely discharged before opening any fitting or connection in the refrigeration system. Open fittings with caution even after the system has been discharged. If any pressure is noticed as a fitting is loosened, allow trapped pressure to bleed off very slowly.

Never attempt to bend preformed lines to fit. Use the correct line for the installation you are servicing.

A good rule for the flexible hose lines is to keep the radius of all bends at least 10 times the diameter of the hose. Sharper bends will reduce the flow of refrigerant. The flexible hose lines should be routed so that they are at least 3 in. (80mm) from the exhaust manifold. It is good practice to inspect all flexible hose lines at least once a year to make sure they are in good condition and properly routed.

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Fig. Fig. 2: Refrigerant line routing and torque values-1992-95 Pick-ups

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Fig. Fig. 3: Single and dual air conditioning system line routing and torque values-1983-91 Monteros

All of the air conditioning plumbing connections use O-rings, which are not reusable.

The internal part of the refrigeration system will remain in a state of chemical stability as long as pure, moisture-free refrigerant and refrigerant oil is used. Abnormal amounts of dirt, moisture or air can upset the chemical stability and cause operational troubles or even serious damage if present in more than minute quantities.

When it is necessary to open the refrigeration system, have everything you will need to service the system ready so the system will not be left open any longer than necessary. Cap or plug all lines and fittings as soon as they are opened to prevent the entrance of dirt and moisture. All lines and components in parts stock should be capped or sealed until they are ready to be used.

All tools, including the refrigerant dispensing manifold, the gauge set manifold, and test hoses should be kept clean and dry.


  1. Clean the sealing surfaces.
  3. Make sure that the O-ring does not have any scratches.
  5. Use refrigeration oil to cover the O-ring.
  7. Connect the fitting, install the fastener, and tighten to the torque shown in the diagram.
  9. When tightening the refrigerant lines, use two wrenches. This will keep the fixed end of one of the two lines stable while the other fitting is being tightened to it.

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Fig. Fig. 4: Air conditioning system refrigerant line routing-1992-95 Monteros