Hi,
Great, yes I recall mine being a pig to fill as the filler hole isn't that easy to get to.
I bought a jumbo copper sealing washer set from eBay for these jobs too as you should not reuse the washers: when you tighten (squash) them they harden. I did try aluminium but I kept melting them when I tried to re-use them (smear with soap, heat up until the soap goes black). Copper are much easier to re-use (anneal), support on a wire and heat up to red. I found with scooters, cars and the van it helped to have a box of new ones LOL.
I'm doing the same as you - longer and longer trips as a gain confidence that everything is OK.
Here's an AC diagram:
If the engine fan kicked up salt water over the engine it could have disturbed the electric clutch at the front on the compressor - so if it all seems to work but never actually engages you may wish to look at that. To look properly however you'll have to take the other engine cover off (drivers seat, fold carpet forward, undo handbrake + bolts, remove cover. Tip: Getting the handbrake bolted back to the cover can be tricky - the bolts don't go in unless the angle is just right.
You may also want to check the 2nd fan - the big electric fan at the front laying flat on the 2nd radiator and AC rad, the sensor is on the engine just below the coolant cap detecting coolant heat that's just left the head. With the ignition on, unplug the sensor and the fan should run. I think that's used for AC too.
My van was modified but not serviced, when I bought it (from Japan), but looked nice and was rust free. I had them change the engine oil and air filter (I had to re-attach the air-filter lid as it was not quite seated correctly). It drove well and the head etc is all good.
I have a small parking lift so I can access the underneath so I decided to change the diff and ATF fluids, on change #4 of the ATF as the new fluid washed out some dirt.
I also changed the front discs and pads as they'd been overheated ('warped') and cleaned the rear drums out. I sorted out the rear suspension which had been lowered excessively and poorly, adjusted the front up too, and trimmed a mudflap that was melting on the bigger exhaust box.
I had to get the spare re-seated and put it in a cover too - it was flat and road grit stopped it from being inflated
I then flushed and modified the cooling system.
Fitted LED lights + regulators everywhere (except for head/fog lamps which were replaced for new Toyota units and super-bright Philips bulbs.
I added a digital temperature controller for the AC.
New radio and rear camera.
New front speakers and tweeters and crossover.
Removed and cleaned headlining.
Added insulation in the roof + painted top of rear blinds white (house emulsion so it stays white) + covered moon roof shade with silver bubble foil on top to reflect heat.
Added switched override and voltmeter for the moon-roof. (Voltmeter tells me it's on, switch does off, acc, on).
Added cruise control.
Added remote locking with alarm.
Added integrated rear foglamp (uk legal)
Modified 2 seat swivel so it swivels to sliding door and locks in place (just while parked up)
So yes, it was going to be a boring Toyota that just worked but it's turned into a bit of a hobby LOL, one day I may upgrade to a new van but it does look nice and very easy to park etc.