on/in the low side.... go to you tube and put in your search engine > 2004 Ford Explorer XLT V6 install freon ac pro
Do yourself a favor and seek out an A/C specialist, you haven't a clue and you will likely mess the a/c system up.
AC systems are closed. If refrigerant is required, there is a leak. Meaning air and humidity is inside. Don't know what a can of the stuff costs, but it will leak out either quickly or slowly depending on the problem. Search the net on how to find the leak and determine if you are capable of repairing it. You will have to pull a vacuum on the system before recharging. Maybe a mechanic shop is better in this case.
Looking for a Used Explorer in your area?
CarGurus has 1,497 nationwide Explorer listings starting at $1,799.
Search Ford Explorer Questions
Ford Explorer Experts
Related Models For Sale
Used Cars For Sale