2 questions for a 98 jgc limited v8
1st, my oil pressure gauge fluctuates with the rpm, is it supposed to be doing this?

2nd, everytime i go duning(offroading in sand dunes) and i turn on the a/c after i'm done, i'll be on the highway and sand will be flying out of a/c vents like crazy. so now i go to this one shop after everytime i finish duning and they blow all the sand out with a high pressure air compressor. but sand still comes out afterwards, not as much. so is the 98 supposed to have a cabin air filter under that black piece under the windshield wipers like almost all other vehicles i'm familiar with. also does anyone know where i can get a diagram of the a/c fan because i'm going to completely disassemble it and clean it out as well as make my own cabin air filter. One more point, the sand comes out only when recirculate is off, when its on barely any comes out.
-if any of this doesnt make sense just say so and i'll elaborate more

1. my jeep does the fluctuation thing too, don't know why and has done so for at least 20000 miles so don't think it is a big deal. Shouldn't go below 35psi though ever.
2. There is no filter on my 1995 grand cherokee with 5.2 V8. What I did was remove the top cover in the engine compartment and glue a couple of pieces of bug screen over the gaping holes. This has helped A LOT.
3. The blower motor falls out from the passenger foot well after undoing a ring of screws, look at the circular protrusion inside the passenger comartmnet and you will see it. You wont be able to get to the rest of the system though. And to remove it is HORRIBLY hard work.

Thanks for the reply, i think i'm just gonna drop the bottom part of the blower motor case and make my own filter and thats it. I had the whole a/c system replaced like 2 years ago but now the cars off warranty and can't afford doing that again.

one quicky, how do i retrieve the fault codes on a 98 jgc limitted? my check engine light isnt on but my abs is but thats cuz i disabled it. just want to see if i can pull up any codes.

don't know about codes (my son takes it to work - nissan to check mine). as for filter you need to put it where intake is under winow wipers at front to prevent anything getting inside. Once inside it is too late.