None of the buttons on the climate control unit work. Checked and cleaned all the fuses, they all look good. Next, pulled the passenger floor panel and disconnected the power cable to the heater blower motor. Ran two leads from a 12 volt battery pack to the male plugs on the blower motor, motor turned on and ran (thank goodness!). Next, connected a working test light to the female plug for the heater blower motor and turned the ignition on and then turned on the defrost. The test light did not light, so I'm thinking the problem is the climate control unit. This is on the 1984 300DT, BTW. Other than the climate control unit, are there any other possibilities?