I have the 350MAV036060 model gas furnace. The blower motor does not come on. LED gives code 12. There is only 1.5 volts coming off the "Heat" terminal when the motor should be running. Is this definitely a bad circuit board? Are they ever repairable? I find aftermarket boards for sale online at half the price of the OEM board. Has anyone installed one of those? Ist it worth the savings?

Appreciate any help. Thanks.

You need to test things with a meter and find out what is wrong. It may not be the circuit board as it rarely is the problem. You can even rewire it with a fan switch and fan relay and through the hi-limit and you are done. You do not even need the circuit board in some models, not all. The only function the circuit board has is fan control and sometimes the board controls safeties for the make-up combustion air and in that case you must have the board. See: https://dl.dropbox.com/u/8010163/AC%20Wiring%20Diagrams.zip
These are some wiring diagrams that may help.