Warm Air Comes Out Of the Vents, and There is Frost On the Expansion Valve

Warm air comes out of the vents, and there is frost on the expansion valve

Probable cause: The expansion valve is stuck closed.

Replace the expansion valve Service and Repair.

Also check for

Climate control DTCs Initial Inspection and Diagnostic Overview

Also check for

Check the old expansion valve for contamination. If contaminants are found, replace the A/C system component that caused the contamination.