What is an evaporator core?
The evaporator core, sometime also called an evaporator coil, is a heat exchanger. Located in or near the vehicle's dash, this part fills with cold liquid refrigerant. As the blower motor blows air across it, the heat from that air is absorbed by the cold refrigerant, and cold air enters the passenger compartment. The warm refrigerant exits the evaporator core and is replaced with cold refrigerant.
You've probably noticed water dripping under a vehicle when the air conditioning is turned on. That water is condensation trapped on the evaporator from the warm air blowing across it, and is completely normal. The case that contains the evaporator core has a drain tube for the water to drip out.
Because moisture is removed from the air, the air conditioning system is a great dehumidifier. Thus, the A/C system is now part of the defrost system. In most later model vehicles, the A/C compressor turns on when the defrost is turned on. Air conditioning isn't just for cold air; it's actually climate control.
Several problems can devolop with evaporator cores because of these wet-dry-wet-dry conditions. First, the moisture can cause mold and mildew to form. Sometimes this can make for some stinky air. There are products available to kill this mold and clean up the smell, and are found at just about any auto parts store. More concerning, however, is that sometimes this mold can clog the drain tube. When that happens, water fills up the evaporator core case, and can drain into the vehicle passenger compartment.
Because the evaporator core environment changes so drastically, again with the wet-dry, leaks can develop as well. There is no real preventive measure one can take; it's just something that happens.
Some experts claim this is bogus, others swear by it, and I do it myself, because it can't hurt. That is, I turn my A/C off a block or two before parking, so the regular air blowing across the evaporator core can dry it off before it's parked for several hours. That will eliminate the moist conditions needed for mold and mildew to grow.
Replacement time for an evaporator core can be lengthy, so always be sure to buy a replacement evaporator coil from a quality source. A poor quality replacement evaporator can cost you more money.
While A/C Parts House sells a lot of Ford and Chevy evaporator cores, we really sell a ton of Chrysler, Dodge, and Jeep evaporators. No matter what evaporator coil you need, you can find it by browsing our catalog.