Symptoms of a Bad or Failing Expansion Valve (Orifice Tube)

An expansion valve is an AC component that is commonly found on many road going vehicles. It is usually installed at the evaporator inlet and works together with the orifice tube to regulate the flow of refrigerant through the vehicle’s AC system. Too much refrigerant flow and the evaporator core will freeze over; too little and the evaporator core will overheat and compromise the efficiency of the AC system. The expansion valve meters refrigerant flow according to evaporator temperature and the load and cooling demand of the AC system. When the expansion valve fails or has any issues, it can cause problems with the functionality and performance of the AC system. Usually a bad or failing AC expansion valve or orifice tube will produce a few symptoms that can alert the driver of a potential issue.

1. AC system performing worse than usual and blowing warm air

One of the first symptoms of a problem with the AC expansion valve or orifice tube is an underperforming AC system. The AC expansion valve and orifice tube work together to regulate the flow of the AC system. If either component fails or has an issue, it can disturb the performance of the AC system, which can cause it to underperform. The AC system may begin to blow noticeably less cold than before and may even begin to blow warm air depending on the severity of the problem.

2. Frost on AC evaporator or coming from the vents

Another symptom of a potential problem with the vehicle’s AC expansion valve or orifice tube is frost coming from the vehicle’s vents. If the AC evaporator or orifice tube malfunctions, it can cause refrigerant to flow unmetered through the vehicle’s AC system. This can cause the evaporator to freeze over, or frost to form or come from the vehicle’s AC vents. Either symptom is a sign that the system is getting too much refrigerant, which will actually hinder its efficiency and performance.

3. AC compressor constantly running

A constantly running compressor is another symptom of a possible problem with the AC expansion valve. If the AC expansion valve fails or sticks open, it will cause the compressor to pump refrigerant through the vehicle’s AC system, even when it may be undesirable for it to do so. This will put an additional strain on the compressor and associated AC components, making them more susceptible to premature failure.

The AC expansion valve and orifice tube are important components to the proper operation of the AC system and any issues with them can lead to AC system problems and malfunctions. If you suspect that your expansion valve or orifice tube may be having an issue, have the vehicle’s air conditioning inspected by a professional technician, such as one from YourMechanic, to determine if the car will need an AC expansion valve replacement or another repair.


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Ben

41 years of experience
1410 reviews
Ben
41 years of experience
Volkswagen Beetle L5-2.5L - Heating AC - Houston, Texas
i am well satisfied with Mr Smith working on my car(s). He replaced the Jaguar fuel pump like an expert, and then he diagnosed the VW bug ac compressor and fixed it on the spot. I would recommend him to anyone with a car issue
Nissan Altima - Heating AC - Houston, Texas
Incredibly nice and took the time to show me the problem, including comparison pictures between my unit and what a new unit should look like.

Peter

43 years of experience
1321 reviews
Peter
43 years of experience
Saab 9-3 L4-2.0L Turbo - Heating AC - Phoenix, Arizona
He knows what he's doing. Very polite and explained everything. I would no doubt use him again. I highly recommend him.
Mazda Miata - Heating AC - Peoria, Arizona
We are so thrilled to have found Peter as our new mechanic. He is very thorough and knowledgeable. He is also friendly, professional, and extremely honest. He explained to us exactly what services were needed on our vehicle to repair the air conditioner and provided us with an written estimate of the cost. He literally saved us thousands of dollars in repair costs. A local major competitor quoted us a repair cost of a minimum of $1,400 and said that the cost would go up to $2,400 if they discovered an additional part was required. Peter charged us only $202, plus performed the work at our home. The air conditioner in our 2004 Mazda Miata has honestly never worked so great--it always blew out warm air. We just assumed it was how that particular car was manufactured. We would highly recommend Peter to anyone who is in need of an experienced and honest mechanic.

Pedro

31 years of experience
78 reviews
Pedro
31 years of experience
Chrysler PT Cruiser L4-2.4L - Heating AC - Portage, Indiana
Pedro was wonderful! He was early first and foremost. He was very professional and he explained things to me. He worked quickly and was very thorough. Very happy with his service.

Manuel

32 years of experience
580 reviews
Manuel
32 years of experience
Ford Taurus V6-3.0L - Heating AC - Long Beach, California
Good guy. Knows his stuff. Knowledgeable and straightforward with diagnostics and repair costs. I’d love to work with him again! Thank you Manuel!

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