Your car's evaporator coil is one-half of its critical air conditioning refrigerant loop. Air conditioning systems use a refrigerant chemical to transport heat from one location to another. In the case of your car, the refrigerant moves heat from your car's cabin to the outside world. The evaporator coil picks up heat from your cabin air and the compressor coil releases that heat into the environment.
Evaporator coils work a bit like radiators in reverse. Like a radiator, the evaporator coil has numerous fins surrounding the internal plumbing. However, the fins transfer heat from the air into the refrigerant instead of releasing heat. Unfortunately, these delicate components can sometimes develop leaks, allowing refrigerant to escape from the system.
Why Do Refrigerant Leaks Matter?
Your AC system uses a refrigerant that quickly vaporizes at standard atmospheric temperatures and pressures. Any leak in the system will allow refrigerant to escape and quickly turn to vapor, disappearing forever. As a result, refrigerant leaks don't produce many visible signs, and you're unlikely even to smell the escaping refrigerant.
Air conditioners also depend on precise internal refrigerant pressures. Under normal circumstances, your system will never lose refrigerant or need a top-up. Without leaks, you can use the same refrigerant charge throughout your car's life. However, leaks that reduce refrigerant pressure can cause numerous problems and even cause premature wear or damage to your compressor.
Why Do Evaporator Coils Leak?
AC systems can develop leaks at numerous locations, although evaporator coils are one common culprit. Leaks often form due to contamination or moisture inside the AC lines, which can cause corrosion that will slowly eat away at the refrigerant plumbing. Evaporator coils can sometimes be particularly vulnerable due to multiple dissimilar metals in direct contact.
Unfortunately, evaporator leaks are also hard to notice and relatively small. Since manufacturers usually install evaporators behind the dash, technicians can't easily trace leaks using UV dye or other techniques. Technicians often uncover evaporator leaks by elimination; when there are no other leaks in the system, the evaporator is the most likely source.
Why Aren't DIY Fixes Effective?
You've probably seen plenty of DIY fixes for leaks in your car, including various leak repair products. Unfortunately, these products introduce additional chemicals into your car's AC system. While they may temporarily stop a leak, they can risk clogging other potentially expensive components. In a worst-case scenario, these DIY fixes will only worsen the problem.
The proper repair for an evaporator coil leak is to remove and replace the affected component. While this repair can be labor-intensive and expensive, it is the best way to get your AC system running again without risking damage to even more expensive parts.
Reach out to a mechanic to learn more about car AC repairs.