I have a Carrier furnace (oil) Model #58CMA120-20 which I recently attempted to install a Ritetemp 6036 thermostat to. The fan and heat do not work. The support desk at Ritetemp recommended that I check/replace the fuse on my Carrier's mother board. I do not see a fuse anywhere on the motherboard. Can you please help me locate the fuse?

See page 4 item 11. If there is a fuse for the low voltage supply it will be on the circuit board in that location. Always replace fuse with like same rate.

http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/58cma-5pd.pdf

It depends on how your board it turned, so all I can tell you is to look close to where the thermostat wires connect to the board. You and looking for a fuse just like the auto fuses, about 1/2 inch square. It will be either a three or five amps.

<changed volts to amps> - KISS

Page 3, upper right hand corner looks like the fuse. As everyone said, it's typically automotive style and has the current rating on the fuse and the item is color coded.

If the new thermostat requires a "C" connection, you must establish that at the furnace control board.