When I turn my t stat to heat it pops my fuse in the circuit bd. The a/c works fine . I looked at the heater elements and they look fine no broken wires.when this happens I see an arc on
Or near the board.please help.

When I turn my t stat to heat it pops my fuse in the circuit board. The a/c works fine.I looked at the heater elements and they fine no broken wires. When this happens I see an arc on or near the board. Please help

The arc may be the fuse blowing.

I would suggest marking and removing the thermostat wires.

Jump R to G at the furnace. The fan should come on. Remove the jumper.

Jump R to W and the fan and heat should come on. The fan my be delayed.

This will tell you if it's the thermostat and or thermostat wiring if it works.