Pontiac Problems? Ask a Mechanic for Answers ASAP
Your '98 does not come equipped with a cabin filter. Have you looked to see if there is a place to put it?
On some of the Cadillacs and Buicks they had the facility to pull the panel off the intake to the system and slip in a filter but yours is not made that way. Take a look but that will explain why you cannot find a filter for your vehicle.
Usually uneven cooling indicates the system is low on refrigerant. Sounds like they missed a leak when the system was serviced.
Please let me know if you have further questions
I am always glad to help. Let me know if you have further questions, if you do not please complete the rating