I have no heat coming from the heater. First noticed when asking for heat after the summer. This car has an electical thermostat heat control. All other climate control operations work fine - vents, AC, fan, etc.

I suspect the mechanicalal door on the heater box or the electrical to it. Both heater hoses (in and out) are hot going into the firewall from the engine compartment.

I need to know where on the heater box under the centre of the dash, the lever/operating arm is located for the heater door? Also how can I determine whether it is an electical versus mechanical problem?