have an older 93' Coleman Horizon 400 240v spa..
manual:
http://team.maaxspas.com/manuals/Horizo ... 201993.pdf

GFCI keeps tripping immediately after power up.
except when the heater is disconnected, naturally thought it was the heater but this is a brand new one, tested it with multimeter and it was fine..

disconnected lights, blower, Ozone still tripping GFCI few seconds after power up.

could it be caused by water that somehow got into the protective flexible hose that caries power from GFCI to the spa?

any help appreciated!

We just had one of these in the shop. Unfortunately, there is not a fantastic answer. Check your sensors and make sure they are still good. If there was water, let it dry up before plugging in any part. If these do not seem to work, it is most likely your board. Boards are very expensive however, so my suggestion would be to check those things out first!

I suspect the heater even though it is brand new. Make sure it is grounded. You can unhook the power at the spa and if it still trips you have eliminated the spa itself. It would then make sense that it's something with the wiring.

Pete
http://www.makesmeshutter.com