Johnson analog temp control

I have a Johnson analog temp controller which has been supplanted in the refrigerators by a couple of Rancos. I would like to convert the Johnson to work with a heating pad, so I can ferment in the garage in winter. Anyone have an idea how to do this?

Could be wrong, but i am confident it is for cooling only.

For the digital version, there is a jumper that is switched to change between heating and cooling modes. I’m almost positive that the analog version is the same.

I went ahead and opened a spare that I had lying around. Nothing inside tells me it can be switched. Photos below.

Based on your photos you would be correct. You have an SPST relay whose contacts close on temp rise above set point. Johnson Controls does make an analog SPDT relay (I have one) with 3 terminal screws. Bottom screw is relay pole, middle screw is to control a heating element and top screw controls a cooling element.

Thanks, everyone.

If the model number ends with “C” or “F”, it’s SPDT.

http://cgproducts.johnsoncontrols.com/MET_PDF/125020.PDF