How to Solve the Frosting Issue on the Low-Pressure Pipe of a Car Air Conditioner?
2 Answers
If the air conditioner freezes due to a faulty thermostat, the thermostat of the air conditioner needs to be replaced. Check if the car air conditioner's evaporator is too dirty; if so, the entire air conditioner evaporator needs to be thoroughly cleaned. When the air conditioner starts operating, if the capillary tube supplies less refrigerant than the normal value, it will lower the pressure on the evaporator, causing the low-pressure supply pipe to frost.
I previously encountered the issue of frost forming on the car's A/C low-pressure line, which typically indicates an abnormality in the air conditioning system. The most common cause of low-pressure line frosting is insufficient refrigerant—a lack of adequate coolant in the system leads to excessive cooling of the evaporator and ice formation on the pipes. It could also be due to a clogged or malfunctioning expansion valve failing to regulate refrigerant flow, or a poorly functioning receiver-drier allowing moisture into the system, forming frost. Air infiltration or faulty temperature sensors may also be the root causes. For solutions, I recommend first checking if the refrigerant level is normal and topping it up if low. Next, inspect whether the expansion valve is clean or needs replacement. Regular maintenance of the receiver-drier is also crucial. If the problem persists, professional equipment should be used to evacuate the system, vacuum it, and then recharge it with refrigerant. For safety, avoid immediately turning on the A/C when severe frosting occurs to prevent compressor damage. Develop the habit of having the system inspected annually before the cooling season to avoid similar troubles. Seeking diagnosis from a professional auto repair shop is the most reliable approach—DIY attempts carry high risks and may overlook deeper issues. In short, addressing the problem early can save significant costs and extend the A/C system's lifespan.
