How do you know if your AC expansion valve is bad?

Asked By: Vern Atorf | Last Updated: 8th May, 2020
Category: home and garden indoor environmental quality
4.7/5 (54 Views . 20 Votes)
Bad Car A/C Expansion Valve Symptoms
  1. 1) Warm Air From Vents. The most recognizable symptom of a bad A/C expansion valve is when you turn on your air conditioner and warm air starts blowing out of the vents.
  2. 2) Frost on the Vents.
  3. 3) A/C Compressor Always On.
  4. 4) Inconsistent Airflow.
  5. 5) A/C System Failure.

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Keeping this in consideration, how do you check a AC expansion valve?

How to Test an AC Expansion Valve

  1. Make sure the AC unit is plugged in or, if it is in an automobile, turn the vehicle on.
  2. Use the manual to locate the thermostatic expansion valve.
  3. Lift the sensing bulb from the suction bulb well.
  4. Hold the sensing bulb in your hands for two minutes or place it in warm water.

Additionally, where is the AC expansion valve located? TXV Location The thermostatic expansion valve is usually mounted inline with the tube that supplies liquid coolant to the air conditioner evaporator. The bulb of the expansion valve is mounted to the outside of the output line of the air conditioner evaporator.

In this manner, what does expansion valve do on AC?

The expansion valve removes pressure from the liquid refrigerant to allow expansion or change of state from a liquid to a vapor in the evaporator. The high-pressure liquid refrigerant entering the expansion valve is quite warm. This may be verified by feeling the liquid line at its connection to the expansion valve.

Does the expansion valve need to be replaced?

I strongly recommend you change the expansion valve. If the clutch failed there is no reason to replace the expansion valve. If it was the bearing, then you may or may not need to replace the expansion valve, depending on whether or not metal shavings were introduced into the refrigerant system.

31 Related Question Answers Found

What causes an expansion valve to fail?

There actually are simple Expansion valves operate under high pressure and cycle through ups and downs of temperature and pressure. The moving parts get stressed by these factors. Contaminates in the system can also cause failure.

How do I adjust my AC expansion valve?

To adjust the static superheat, turn the valve's setting stem. Turning clockwise increases static superheat and effectively reduces refrigerant flow through the valve. Turning counterclockwise reduces static superheat and increases refrigerant flow.

How much does it cost to replace an expansion valve?

The average cost for an air conditioning expansion valve replacement is between $240 and $336. Labor costs are estimated between $170 and $215 while parts are priced between $70 and $121. Estimate does not include taxes and fees.

What happens when an orifice tube is clogged?

Clogged Orifice Tube. The orifice tube can become restricted and clogged with debris. A clogged orifice tube is typically caused by compressor failure. When this happens, little pieces of metal and aluminum shrapnel will be found in the tube's screen filter.

How long does an expansion valve last?


There isn't a specific lifespan of the valve, it's more just a wear and tear kind of situation. Obviously the more you use the air conditioning, the quicker it will wear down.

How do you know if the expansion valve is bad?

The most recognizable symptom of a bad A/C expansion valve is when you turn on your air conditioner and warm air starts blowing out of the vents. This would obviously mean that not enough refrigerant is making its way to the core of the evaporator.

What does a bad AC compressor sound like?

Loud noises when the compressor is running
Another potential symptom of a failing AC compressor is loud or unusual noises. A worn bearing will produce a high pitched squealing or grinding sound, while a seized bearing will produce a grinding noise or a noticeable belt squeal.

Can a expansion valve be cleaned?

In these cases, it is far more beneficial to the customer if the valve is replaced instead of cleaned. It is very difficult to determine if a Thermostat Expansion Valve is clean. Any debris or contamination at the TXV can prevent proper flow of lubricating oil through the system and its return to the compressor.

Why is AC pressure too high?

When the pressure of the AC system is too high this might indicate a leakage or diminishing amount of refrigerant, both of which require immediate attention. If the AC temperatures are abnormally warm, this could indicate an issue with the compressor that might need repair or replacement.

What is the difference between an expansion valve and an orifice tube?


Like an expansion valve, the orifice tube is used to control the amount of refrigerant entering the evaporator. The diameter of the orifice tube is similarly small to that of the passage inside the expansion valve, but there is one big difference between orifice tubes and expansion valves.

Where is the expansion valve located in a refrigeration system?

The TXV Expansion valves reside between the evaporator and condenser in the refrigeration cycle. The main body of the TXV is made of brass with a refrigerator inlet on the bottom of the valve and a refrigerator outlet on the side. On the adjacent side is a cap that can be removed to adjust the superheat.

What happens when the expansion valve goes bad?

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.

How do you replace an expansion valve?

  1. Step 1: Become Familiar With Air Conditioner Unit.
  2. Step 2: Remove Refrigerant from Air Conditioner.
  3. Step 3: Disconnect Lines from Dash.
  4. Step 4: Remove Glove Box to Access Evaporator.
  5. Step 5: Remove Blower Motor.
  6. Step 6: Remove Expansion Valve.
  7. Step 7: Install and Replace.

Where does the AC orifice tube go?


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.

How do you know if you have a clogged Txv valve?

Six Steps – Checking a TXV
  1. Check the sensing bulb, make sure it is properly connected to the suction line.
  2. If the bulb has been insulated by the manufacturer, make sure the insulation is intact.
  3. Check the equalizer line for restrictions, kinks, or signs of frost.
  4. Some manufacturer's have an inlet screen that can become clogged with debris.

What causes low suction pressure on AC unit?

The fact that these readings are normal indicates the low suction pressure is not caused by low refrigerant, but insufficient heat getting to the evaporator. CAUSE #2: Defective, plugged, or undersized metering device. Higher subcooling indicates excess refrigerant backing up in the condenser.