i.e. no hot air, just cold. Indicator lights work, A/C works, defrost via cold air only, fan blower works.
Looking ahead until he comes home and I can look at it, I suspect the problem could be one of:
(1) heater valve, perhaps stuck, does not rotate? less likely clogged.
(2) broken cable, or detached at either heater valve or climate control
(3) climate control module $465 new, $50-75 if used
Question for Climate Control module: Does moving the temperature slider lever sideways simply drive the cable to the heater valve, i.e. strictly mechanical connection, no electrical solenoid that moves the cable.
To diagnose, I'd start by checking whether the heater valve is stuck, i.e. does it rotate via cable. Then I'd pull the Climate Control module to see if the cable is attached, and whether sliding the temperature lever moves the cable.
Any other ideas for preliminary diagnosis? If I'm lucky, its just the cable assembly, which is just $15 from dealer.