GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Expansion Tube


The factory installed air conditioning systems for vehicles covered by this manual utilize an expansion tube (orifice). The orifice is used to regulate the flow of refrigerant to the evaporator, so is placed somewhere in-line between the condenser and the evaporator. It is designed to ensure that the evaporator remains as full of liquid refrigerant, as possible without allowing any liquid to pass into the compressor suction line. The orifice is usually found in the evaporator inlet, often at the liquid line connection.

Please refer toChapter 1 of this manual before discharging/recovering the A/C system or disconnecting air conditioning lines.Damage to the air conditioning system or personal injury could result. Consult your local laws concerning refrigerant discharge and recycling. In many areas it may be illegal for anyone but a certified technician to service the A/C system. Always use an approved recovery station when discharging the air conditioning.


An orifice tube removal and installation tool (J-26549) is required to perform this procedure.

  1. Either discharge and recover the refrigerant using a suitable recovery station or have the system discharged by a professional shop.
  3. Disconnect the negative battery cable.
  5. Disconnect the refrigerant inlet line at the accumulator (vehicles through 1991) or the evaporator tube from the evaporator (1992-93 vehicles). If the connection utilizes an O-ring, remove and discard it. A new O-ring should be used during installation.
  7. Remove the orifice from the line using tool J-26549. If difficulty is encountered on 1992-93 vehicles, first remove as much of any impacted residue as possible, then carefully apply heat (using a hair drier or heat gun) to the dimples on the inlet pipe. Hold the heat source approximately 1 / 4 in. (7mm) away from the inlet pipe, while using the removal tool to twist and push-pull the component to help free it.

If the system is equipped with a pressure switch near the expansion tube location, it should be removed PRIOR to heating the connection in order to prevent switch damage.

To install:
  1. Install the new orifice into the line with the shorter screen end toward the expansion tube (through 1991 vehicles) or toward the evaporator (1992-93 vehicles).
  3. If used, position a new O-ring to the connection.
  5. Reconnect the line and tighten to 18 ft. lbs. (24 Nm) for vehicles through 1991 or to 13 ft. lbs. (17 Nm) for 1992-93 vehicles.
  7. Connect the negative battery cable.
  9. Either recharge the A/C refrigerant system or have the system recharged by a reputable shop.