bypassing the a/c thermo dial switch ?
 

Got all new r12 and it was glorious for a few days there but now the temp sensor turn knob has stopped working, I understand I can bypass it by removing the center console cubby and turn knob and removing the switch.

Anyone have a photo - write up on this bypass ?

Or anyone have a write-up on adapting a new switch for a 79sc as I understand they dont sell the old switches anymore.. must retrofit a new one..

Many Thanks,

JB

Email sent.

The circuit is rather simple, two wires, so its in series.
Open the center console, locate the thermostat on the left (usually),
disconnect green and green/white wire from its terminals and connect
to a 'switch' (not much amperage). However forgetting turn off the switch
can cause other issues such as freezing the evaporator core or damaging a compressor.

Maybe you want to spend a little time trouble shooting the circuit, a decent schematic can be found here on PP. Replacement thermostat's are available and R&R is rather easy for DIY.

kuehl, I have done a you described; however I register no current at the green and green/white wires on the multimeter? what is my next step backwards?

Did you turn on the fan speed switch on the right and then check it?

yes sir, got voltage there--fan speed shows varying voltages depending on pins selected. still nothing out of the green and green/white wires

On the back of your fan speed switch's mating plug, the circuit for an 89 shows a green/white wire (which feeds the thermostat and condenser fan relay.. etc.) Check for voltage on the green/white wire's crimped terminal where it exits the switch plug when you have the switched turned on. You an review the schematic on a 89 on in the shop manual page 970-51.