Lincoln A/C Orifice Tube

The A/C Orifice Tube Provides a Fixed Restriction

An A/C orifice tube meters refrigerant through a small fixed opening before it enters the evaporator. Unlike a thermal expansion valve, it does not continually move a valve opening in response to operating conditions. The surrounding system manages cooling using the design intended for that fixed restriction.

An A/C expansion valve serves a related metering purpose in a different system arrangement. It is not a direct upgrade for an orifice tube. Replacing a failed metering part should preserve the air-conditioning system's original operating design.

Bore Size Matters More Than Outer Similarity

The calibrated opening determines the tube's restriction. Two parts with similar housings can have different internal dimensions and operating applications. Color may help identify a specified part, but it is not a universal compatibility code across manufacturers and designs.

Use the intended metering specification together with the outer shape and sealing arrangement. This preserves the refrigerant flow the system was designed to use.

The Screen Is a Clue to System Condition

Many orifice tubes include a screen that can collect debris. Material found there can help guide diagnosis, but the screen is not a substitute for the system's dryer or accumulator. A blocked tube may be the visible result of a problem elsewhere in the refrigerant circuit.

During replacement, the condition of the removed part should inform the rest of the repair. Installing a clean tube without addressing contamination can leave the replacement exposed to the same debris. Identify the contamination source and follow the required cleaning and component-replacement procedure rather than treating the small tube as an isolated maintenance item.

Frequently Asked Questions