Where the orifice tube is located in your car’s AC system
Learn where the orifice tube is located in a car’s AC system
The orifice tube is a simple yet vital component in many automotive air conditioning systems. This small, cylindrical device plays a critical role in the refrigeration cycle, acting as the expansion device that separates the high-pressure and low-pressure sides of the AC system. The orifice tube is typically located between the condenser and the evaporator, typically in the liquid line.\
Where to look for the orifice tube
In most vehicles, the orifice tube is located in the liquid line near the firewall, just before the evaporator. However, its exact position can vary depending on the vehicle’s make and model. Some manufacturers integrate the orifice tube into the liquid line, making it less accessible for replacement
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
The 5 different types of Auto AC orifice and expansion valves
How to replace an orifice tube
Before you replace an orifice tube, 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 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
Recover and evacuate your car’s AC system
- Buy or rent a refrigerant recovery machine.
- Attach the manifold gauge set to the high and low side ports on your car’s AC system
- 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 a 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.
Lubricate new O-rings and gaskets with AC oil and install in the 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 it 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 like 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.
New and clogged AC orifice tube. Clogged tube shows evidence of “Black Death.”
©, 2018 Rick Muscoplat