Mechanic Glossary

A/C Evaporator Core

A radiator-like heat exchanger located inside the vehicle dashboard that absorbs heat from the cabin air as liquid refrigerant boils into a gas.

The evaporator core is the part of the A/C system that actually cools the cabin. Hidden deep inside the dashboard HVAC case, cold liquid refrigerant flows through its aluminum tubes. The blower motor pushes warm cabin air through the external fins. The refrigerant absorbs this heat, causing it to boil and turn into a gas. This leaves the air passing through the vents cold and dry. Condensation forms on the cold fins, dripping down into a tray below.

Evaporators are prone to leaks because their aluminum walls are thin. Road salt and moisture corrode them, creating pinholes that let refrigerant escape. Finding these leaks is hard because the core is hidden. Mechanics use electronic sniffers or inject ultraviolet dye into the lines to search for traces under the dashboard or at the water drain tube outlet.

Frequently Asked Questions

The evaporator drain tube is clogged. Condensation cannot drain outside, so the water overflows the HVAC case and spills onto the carpet. Clearing the tube with compressed air fixes it.
Mold and bacteria grow on the damp fins of the evaporator core. Spraying a specialized foaming disinfectant cleaner into the intake vent or drain tube will kill the mildew.
It is expensive, often costing between $800 and $1,500. The part itself is cheap, but the technician must remove the entire dashboard and steering column to reach the HVAC case, which takes 6 to 10 hours.
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