Rick's Free Auto Repair Advice

Where is the orifice tube located?

Here’s where the orifice tube is located

Auto AC orifice tube locations

Because of the way an orifice tube works, it’s usually located on the inlet to the evaporator coil. However, on some vehicles the orifice tube location varies. Sometimes it is built into the liquid or high pressure line or inserted into the high pressure line right where the line connects to the condenser. When the orifice tube is built into the line, it’s referred to as a Liquid Line Orifice Tube (LLOT) or a Suction and Liquid Line with Orifice Tube (SLOT).

The orifice tube may be located:

In the inlet tube to the evaporator

Built into the high pressure liquid line

Inserted into the high pressure line near the condenser

ac expansion valve types

The 5 different types of Auto AC orifice and expansion valves

How to replace and orifice tube

Before you replace an orifice tube, LLOT or SLOT, make sure you understand how an orifice tube system works and ensure you’ve done the right testing to conclude the problem is actually caused by the orifice tube. Replacing the orifice tube requires you to completely evacuate the AC system and disconnect the high pressure liquid line. It’s not a fun job.

AC orifice tube

AC orifice tube system

What you’ll need to replace an orifice tube

• Needle nose pliers

• Orifice removal tool

• New receiver/drier

• AC line disconnect tool

• Replacement orifice of the exact same color and part number as the old unit

• New AC O-ring and gasket kit for your vehicle

• Refrigerant oil

• Refrigerant recovery machine

• AC vacuum pump

• AC manifold gauges

• AC refrigerant scale

• Replacement refrigerant

ac tools

Recover and evacuate your car’s AC system

  1. Buy or rent a refrigerant recovery machine.
  2. Attach the manifold gauge set to the high and low side ports on your car’s AC system
  3. Recover the old refrigerant (It is illegal to vent the refrigerant into the atmosphere)

Disconnect the high pressure line from the evaporator coil

Use the line disconnect tool to detach the high pressure line from the evaporator

Remove the orifice tube using needle nose pliers or removal tool. Note the orientation of the orifice tube. It must go back in the same way. Lubricate the O-rings on the new orifice tube with AC oil. Insert the new orifice tube into the evaporator or LLOT or SLOT.

replace orifice tube

Lubrication new O-rings and gaskets with AC oil and install on line

Reconnect the liquid line to the evaporator or condenser and follow factory specs for tightening (if required).

Replace the accumulator

Always replace the accumulator when replacing an orifice tube

Evacuate the system

Add AC oil

Measure how much oil came out during the recovery process and replace with the same amount of oil

Evacuate the AC system

Attach the vacuum pump and pull a vacuum on the entire system for at least 30-minutes

Recharge with refrigerant

Using the refrigerant scale, recharge with the EXACT amount of refrigerant. Overcharging by as little as 2-oz can dramatically reduce the performance of your car’s AC system. MORE is NOT better!

WARNING about plugged orifice tubes

Most orifice tubes fail due to contamination in the AC system due to sealer, oil degradation or mechanical deterioration. Replacing a plugged orifice tube without solving the root problem will result in another plugged orifice tube. If your orifice tube looks the one below, don’t fool yourself into thinking you can get by with just a new orifice tube. You’ll have to replace the compressor, condenser and even the evaporator.

AC orifice tube

New and clogged AC orifice tube. Clogged tube shows evidence of “Black Death.”

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat

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