The first step is to get the A/C Evaporator Core system emptied by a service department of a dealership or an automotive air conditioning shop. The second step will be to take out the heater/air conditioner housing and place it on a clean work area. Continue by removing the A/C Evaporator Core fasteners, part the housing, and, making every effort to be careful, take out the A/C Evaporator Core out of the heating A/C housing, being careful to remove the fasteners on the top and side of the housing. Installing To install, just reverse the order of removal, and any insulating or sealing material that was originally used must be installed around the A/C Evaporator Core pipes and the core itself. New O-rings should always be used on fittings of the A/C Evaporator Core system when reinstalling them. In case of a replacement of A/C Evaporator Core with the new one, pour in fresh refrigerant oil into the new part, but make sure it is compatible with R-134a. Last but not least, empty the system, refill it and leak test by the shop which carried out the first discharge.