On models equipped with air conditioning, the heater and air conditioner are completely separate units. The heater removal procedure is the same as outlined here. However, be certain when working under the dashboard that only the heater hoses are disconnected. The air conditioning hoses are under pressure. If disconnected, the escaping refrigerant will freeze any surface with which it comes in contact, including your skin and eyes. Refer all air conditioning work to a qualified mechanic.