Kia Optima DL3: Heater / Heater Core

If you're installing a new heater core, add refrigerant oil (PAG OIL).

Replace the O-rings with new ones at each fitting, and apply a thin coat of refrigerant oil before installing them. Be sure to use the right O-rings for R-134a, R-1234yf to avoid leakage.

Immediately after using the oil, replace the cap on the container, and seal it to avoid moisture absorption.

Do not spill the refrigerant oil on the vehicle; it may damage the paint; if the refrigerant oil contacts the paint, wash it off immediately.

Apply sealant to the grommets.

Make sure that there is no air leakage.

Charge the system and test its performance.

Do not interchange the inlet and outlet heater hoses and install the hose clamps securely.