Hotpoint aquarias fdf784, dishwasher, showing A3 when in the middle of a cycle?

Hi, I had the same fault, first check the feed or drain isn't blocked, you can do this by pulling the machine out and disconnecting the inlet pipe and checking the filters in the end of the pipe and the dishwasher inlet. Then check the drain still works. Take the drawers/baskets out, remove the drain pipe, get a bucket for the drain pipe. Then get someone to add water into the bottom of the dishwasher and wait for it to drain out of the drain pipe (the drain will need to be at a lower height than the bottom of the dishwasher for gravity to work, it is no longer pumped because you turned it off before all this didn't you :) !)
If it drains fine then its not the drain at fault. If it doesn't you'll have to unblock that pipe somehow, you may have to follow the procedure to unblock the pump below.
If it drained then its most likely to be the pump thermistor/ fuse/ overheat cut out.
You will need access to the bottom of the dishwasher.
Drain it first! and have towels ready.
Tip the whole unit forward onto its door, use one towel to protect the facia.

There is then an access panel at the base of the machine.
using a thinnish screwdriver you can un-clip this at the bottom of the panel and withdraw the panel upward and outwards, you should then see the internals of the machine (wires, pumps, programmers etc.) Where the drain pipe passes inside the machine it will then continue to the drain pump, a small pump with a connector with 2 wires on it (mine were blue but I cant vouch for yours) pull out the rest of the drain hose, it is just pushed into the pump. Stick the corner of a towel down the pump outlet to drain as much water out first.
This pump can be removed by rotating it towards you after you depress the small clip which prevents this happening, be careful the wires are very short and dont give much room for this, (it would be better if you could disconnect it but it is very fiddly! be confident in what you are doing or leave it)
The pump should then withdraw to the right, and the reason for the over heat should be obvious (the pump was jammed on mine by a small piece of chipped plate, the size of a finger nail) the pump may also be a little warm. Do NOT poke anything sharp down the pump outlet to clean it as there is a diaphragm which acts as a non return valve there which is very delicate.

In true Haynes manual fashion........ re-assembly is the reverse procedure.
Good luck, hope it helps.

PS I am not a dishwasher mechanic, I am a pilot, but quite confident at DIY, mechanics and electrics etc so think before you do anything, and disconnect the appliance from the electricity, electric shocks hurt, LOTS.