I need a wiring diagram (color code) for an old Lennox Apr 11, 2010Meet the Experts. Need wiring diagram for lennox 84W88 installation. System Need wiring diagram for lennox 84W88 installation. System is a Lennox Heat pump with outdoor compresor/condensing unit part No. HP26-042-7P, serial no 5800E. Replacement defroster control board (84W88 At the present time, I have a 1980,s Lennox thermostat and At..Let me have the terminal letters and wire colors and I can match them for you. RussRed to R power Orange to O reversing valve Green to G Fan Yellow to Y1 Cool Since you do not have white Black to W1. Blue to C common Put a jumper..This not standard color code. This Lennox from the 60s and 70s. You do not need L and t on new tstat. Did you wire it like you just showed me her..Yes everything should be connected in air handler. If it is not working you blew a fuse in air handler. The wiring is probably Ok. But if you did n..Great get back with me. Russ How to Safely Dispose of an Old Mercury Thermostat | FAQs Lennox is a partner with organizations like the Thermostat Recycling Corporation (TRC), which facilitates the collection and proper disposal of mercury-containing thermostats. To find a drop-off site in the U.S., click here; in Canada, click here.