Can't seem to find a wiring diagram online for it. You may be able to see them and trace back, they'll look like little copper cylinders with a 2core cable coming out the back, there should be 1 on each coil for coil temps, and one on the 'return air'. It's the return air that'll be the one your after.

However, the fact that it works when you restart it could indicate it's tripping on LP/HP.