Hotspring hottub heater not working

I am betting your pump has air in it. You will have to figure out how to purge the air out or prime your pump.

is the heat indicator light showing on the topside panel? If the pump is running and there is not enough water flow to activate the pressure switch then the heater will not come on.
If the filters are too dirty there may not be enough water flow to activate the pressure switch which sends the power to the heating element.
You just may have a bad heating element.

Hi,
If your Coleman has Balboa electronics 'PR' is to notify you that it is in priming mode.
It could also be your pressure switch. On most tubs the pressure is mounted on the heater. If this switch is not reading correctly it could shut the spa down to prevent heater overheating.

you may not be getting enough power to support all of them at once

Hello,
Assuming there aren't any other faulty electrical components your GFCI will trip as a result of the heater element short circuiting.
Typically this happens when water infiltrates the heater element's protective outer coating and comes in contact with the internal heating coil. The culprit could be corrosion but usually it is a pin sized hole in the element which will lead to a short circuit.
When this happens the element has failed and cannot be repaired it must be replaced.

Send me a picture of the topside to [email protected]

Probably a ground Id check that water did not get into any ele.system

'OH' means 'over-heat'.

Basically the high-limit temperature sensor has detected a temperature far in excess of what it should be.

Check the filter(s), water flow, pump etc....

Regards,
Ian.
http://hottub.synthasite.com