I just did this on my 94, For anyone else who wants to do it the belt was a NAPA 25-060725 which is 73 1/4 inches long.
Google Pontiac boneville ac compressor bypass pulley. There are a few places that sell a replacement pulley that goes in the spot of the compressor that allows use of the original serpentine belt.
under car folow ac lines into small tube protruding out near them
Check the fan relay.
underneath the dashboard on the passenger side.
the ac condensor on a 1998 Pontiac Bonneville is right in front of your radiator not hard to change at all.
low refrigerant charge?
Is this a 2003 Pontiac Bonneville? I need this answered for this year and make.
Before you remove the evaporator core from a 1998 Pontiac Bonneville you need to have the air pressure discharged. You will then need to remove the AC unit. You will need to remove some screws before you can remove the evaporator.
presuming that your GT is very similar to my '96 non-GT, yes. There are two belts available. One for cars with AC and one for cars without AC. If you buy the one for the cars without, you can bypass the condenser.
10w30 any major brand. I recommend you use an AC/Delco, Purolator, Wix, or Bosch filter.
Glove box & behind passenger headlight
1. Low on freon. 2. Electrical problems. 3. Vacuum problems. 4. Control head problems.