First have you discharged the system? If you have any pressure you will not
be able to disconnect the lines and if you did you could be injured.

There are spring lock disconnect tools, and then there are good spring lock disconnect
tools. The ones sold at most chain parts stores (Auto zone, Advance, Pep-Boys...) are
one step up from junk and will only work on good, clean fittings. These tools are either:
 All white one piece plastic that snap over the line. (The better of the bad), or
 Multi colored one piece plastic, flat with a ring around the center hole. (The
absolute worst). Each size is a different color. I've been there and done that
numerous times with these tools when I didn't have my "good" set with me. They are
usually as bad as not having the tool at all.
 The white ones are a slightly stiffer plastic and work better, you have a chance. If
you have the multi-colored ones, you may as well stop now.
 The "real spring lock tools" are 2 pieces, hinged and spring loaded and made of hard
plastic. They clamp around the entire fitting. IIRC, they are about $50 for a set that
covers the AC sizes. There are also 2 sizes for fuel lines. NAPA used to carry them. I
got mine from MAC Tools. They were pricy but they have paid for themselves many times
over. Using my set, I've only had 3 SL fittings that I couldn't separate. That's in
~20 years and all 3 were Gen I Taurus Evaporator outlet fittings. There was some
electrolysis going on. Ford Tempo evap. outlets could be tough also. Your E-van
shouldn't be at all difficult.
 Don't do the epoxy thing. The oil will weaken the epoxy and it will leak. Then the
real repair will much cost more. Buy the correct tools and fix it right. You will
still save $$$. Stay away from "AC system sealers", they can wreak havoc on your
system and cause HUGE repair bills when they don't work.
 I'm sure you are aware that, since the system is empty, you need to replace the
accumulator\receiver-dryer and pull a hard vacuum on the system before you charge it.
In case you didn't know, thats what you have to do. Especially on a motor home chassis.
 That's an R-12 system. Being an E-350 motor home chassis, It will take poorly to an
R-134a conversion, if that is what you're considering, especially if the cab AC is
tied into the living compartment AC (I can't see Coachmen doing this, but anything is
possible). I know this from experience. The condenser is too small and the underhood
temps are too high. Vans in general are marginal candidates for conversion. IF you're
converting to R-134a and IF the front AC isn't tied into the rear you also need to
change the orifice tube to the next size smaller (Orange, IIRC).

 I'm not trying to be a smartass or talk you out of fixing your problem, I'm just
trying to let you in on the facts. AC repair is more than just fixing the leak and
charging the system. if you need some assistance, email me and I may be able to help.
            Regards, Tom Adkins
 PS, At least check out the Forum at www.aircondition.org. They can offer a lot of
help also.