My friend has a Coleman heat pump model 3736-811 with a gas furnace. He bought a Honeywell RTH 7500 thermostat to replace the old one.
The wires on the old thermostat are: W2-grey, G-green, R-red, L-white, X-black, O-orange, Y-yellow, and B-blue.
The problem is, the instructions say, if the L terminal is used the C wire must be connected. But, there is no C wire. I would appreciate any help.
Lobo