Carrier ignition won't shut off

[freelunch]

I just helped a friend install a Carrier 58SS060-CC forced air gas furnace in his shop.

Initial tests went well except that the electronic ignition keeps firing even after the main blower comes on, etc. I let the furnace run for about 30 minutes (disconnected the igniter) but it still wanted to run the igniter (ambient in the shop was 50 F).

It is an updraft gas furnace with a manufacture date of 1980 (I couldn't find a manual online).


There is a dial on the side of the PCB but I did not see the mechanical limit switch that I am familiar with..


Thanks for any help!


Steve