I'm trying to convert +/-12VDC to +/-24VDC to power a DC motor in both directions. I've tried using a step-up converter like this one, but when I feed it -12VDC, it doesn't output anything. Is there an electrical component that will output +24VDC when fed +12VDC and output -24VDC when fed -12VDC? Total noob here just trying to motorize a skylight with a chain actuator, so please excuse my limited understanding.
I don't think you need a negative supply - just use a double-pole relay to reverse the polarity.
You probably need a center-off switch to allow you to stop the motor wherever you want - or a separate off/on switch.
(You probably killed the DC-DC converter when you connected it with the wrong polarity.)
EDIT due to OP's comment that the controller outputs +12V or -12V...
When the controller outputs +12V, the upper relay will operate. When it outputs -12V, the lower relay will operate.
EDIT 2 Changed the upper relay to DPDT to prevent short circuits should both relays somehow become operated at the same time.