I have a ul electric furnace that works fine other than it won't turn off. I have to turn of the main power in order to turn it off. I read that this could be the relay. If so how do I replace it if not what could be the problem. Please help Thanks

If it is only the fan running when thermostat is off, it is the fan relay. If it is blowing warm air when the furnace should be off it is a sequencer. Either way I would have an electrician or HVAC tech mess with it. It's dangerous and a sequencer will be hard for you to purchase.

Sorry not more help.

I replaced some wire that we burnt and changed the thermostat and now everything is working find only when I turn on the ac the heat comes on too. Can you help thanks

I would carefully compare the wires you replaced with any instructions that came with the thermostat and any wiring diagram on the furnace. Connections are more important the wire color. It isn't essential that you have a red wire running from one R terminal to another, but both ends of the same wire needs to be connected to the R terminals, etc.

If it is a resistance electric furnace, it should use the same color codes as a GFA. Heat pumps have some other connections.

Usually there is a 24 volt AC transformer in the furnace with the secondary winding connected to a red wire running to the thermostat and a blue wire, common, to the gas valve, A/C relay, and fan relay. From the thermostat there will be white wire to the gas valve, yellow to the A/C, and green to the fan. The thermostat is wired to switch the power from the red to the white, yellow, and green as needed with the blue completing the circuit. Most thermostats and furnaces have the contacts labeled R, B or C, W, Y, and G for the corresponding wire colors. It may be wired to have the A/C control wires return to the furnace and its controls and then a second wire goes to the A/C unit. Internal wiring may replace the green wire if the thermostat does not give you the option of fan only or continuous fan. Digital or programmable thermostats may need the blue wire connected to them.

If you can't find a problem that fixes it, call a pro as Northern said.