Chevy & GMC Vans

I hope this is the right area for maintanance questions. Have a 03 astro 153k miles everyting is fine but want to know about getting a tune up and fluids change. Plan a long road trip out west in a few months. What do I need to get done? It runs and shifts fine only real problem that bothers me is the ac cuts in and out when Im on the highway blower runs fine just stops blowing through the front vents.
Im only getting the tranny fluid changed and filter I already read about that.

If you don't know the status of the last time anything has been changed, change all fluids and filters. Just don't wait until right before your trip

The vents changing like that is 99% of the time a leaking vacuum hose/line. https://sites.google.com/site/astrosafa ... ac-airflow

Its at the shop now hes changing the tranny fluid and filter I went the route of tune up plugs wires ect. I didnt want blow too much dough at one stop. I already told him about the ac cutting out that I want fixed before it leaves the shop. Its very hot where I live.
After this stop at shop should I do the fluids and filters next?