Coleman Evcon, Green Light flashes 4 Times

[Bruce]

My furnace is a Coleman Evcon. Today it wouldn't shut off and lightly blows cold air. I had to turn off the breaker to shut it down.

I read several of the posting on the site and diagnosed the problem by finding the green light flashing 4 times indicating the limit circuit is open.

I found 3 of them and tried to push the red reset button but got nothing. How do I know which one to replace, or is there something else I should be checking.

[philly]

You can test the limit switches with a simple radio shack ohmmeter,lifting one lead off the individual switches. They should have very little resistance under 1 ohm .
Or jumper each switch one by one .
Be sure to turn off the furnace power , add the jumper strap and turn power on .
On other posts about the 4 flashes , a failed limit switch may run the furnace blower as a prevention of a failed limit switch overheating the furnace .