Replaced an O-ring and schrader valve on the high side last month and in only a month it leaked back down. AC shop says that high-side pressures are too high and that points to a clogged expansion valve, and is what is causing my blown high side seals. The expansion valve is apparently the first part the put in the car before they build the entire damn thing around it.
Neither is appealing. Now, if I understand correctly, the expansion valve has no moving parts. It's basically just an orifice - right? If that is the case, and it's got crap in the orifice that won't pass, then it seems like back flushing it could clean it out, without having to disassemble the dash. I'm tempted to just keep adding , but if the high side pressures are really that high, then I don't want to cause other issues.
Thus looking for the quick-n-easy on the expansion valve. I don't know about blowing the tube out, but I know that during any service they always recommend replacing that valve. I do know that adding too much Ra can blow the shaft seal in the Compressor. I found that out first hand.. Replacing it is easier than you think.
Take out the glove box, then the evaporator core is in the box that is held in with two straps. Undo the straps, pull out the evaporator, replace the expansion valve, done. How do they fail?
A TXV may fail either too far open or too far closed. 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.
Obviously the more you use the air conditioning, the quicker it will wear down. As the frost melts from the sensing disc, the pressure to rise to the first reading you recorded. If the high pressure dropped by about psi and then returned to the starting pressure you recorded once the frost melted, that confirms the expansion valve is not plugged and the sensing disc is working properly.
As the expansion valve operates under high pressures and is temperature sensitive, improper working conditions, as well as impurities inside the loop, can cause its deregulation and malfunction. Place the bulb into hot water. This should cause the expansion valve to open allowing more refrigerant to pass through the TXV into the coil.
Suction pressure should rise, and super heat should drop. Opening of the valve should be relatively quick. Last Updated: 15 days ago — Co-authors : 11 — Users : 7. Save my name, email, and website in this browser for the next time I comment. Notify me of follow-up comments by email. Notify me of new posts by email. Home Answers About. Sign in. Forgot your password? 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.
On TXV systems with high superheat, be sure to check the subcooling as refrigerant is added. 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.
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 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.
Estimate does not include taxes and fees. 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. 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. Q: How do they fail? A: A TXV may fail either too far open or too far closed.
However, there are 4 other warning signs of a damaged AC evaporator: The cool air is weak or no cold air is blowing at all. You notice a strange odor when using your AC system. The AC compressor will not activate.
The AC temperature will vary. Usually the vehicle will display a few symptoms when the condenser fan has failed. Lukewarm air. One of the first symptoms that a fan has failed is the air coming from the vent being warm.
Car overheating while idling. Burning smell when the AC is on. A TXV being restricted will cause the evaporator, compressor, and condenser to be starved of refrigerant.
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