Q: How to remove and reinstall the orifice tube in the air conditioning system of Cadillac DeVille and DTS?
A: Seville excluded, the 1999 models require discharging the air conditioning system and recovering the refrigerant before continuing. You should use two wrenches to separate the high-pressure line of refrigerant so that it does not twist. The orifice tube which is located in cowl area near high pressure line and just ahead of evaporator can be found at fitting junction next to where orifice is sited. It has a fixed diameter orifice and mesh filters at each end and needle-nose pliers can be used to take it out. Orifice tube serves as a refrigerant metering device converting it into low pressure liquid/vapor mixture from a high pressure liquid. It can be taken out with needle nose pliers. In case grit hasn't plugged screens nor been torn off screens' plastic housing nor hindered brass orifice within plastic housing, then one can still use this orifice tube again. On installation, insert the shorter end of expansion tube first towards evaporator; also tighten back fitting and refrigerant line then evacuate, recharge, and leak-test system. Discharge the air conditioning system and recover refrigerant for 1999 Seville, as well as 2000-2005 models too. Two wrenches should be used when disconnecting air conditioning lines around accumulator location. Flared tubing should be separated from line when they are disconnected from filling pipe leading to evaporator where you would find an orifice tube which is a tubular structure with a fixed-diameter orifice on either side of this tubing while using needle nosed pliers remove it as well . It acts as a meter for refriggerent changing it from high pressure liquid into low pressure liquid/vapour mixture; if none of these conditions exists then reuse this orfice tube.The reverse way of removing things involves inserting the shorter end of expansion tube first towards evaporator after repeating tightening back fitting and refriegerant line then evacuating, recharging and leak-testing system.