I have a nordyn furnace. I replace the inducer motor cause it was making a noise and would not run all the time. I also replace a limit switch that is built onto the inducer motor. This limit switch keeps triping and it throws a code of "limit circuit open or external load on "w"." I can disconnect the two wires to the limit switch and short them together and it runs fine. My question is where do I look to fix the problem? I just spent $226.00 for the new inducer motor and limit switch. It's getting expensive.

The limit switch you are bypassing,, if the furnace works while its bypassed,, must be bad

I just had the same problem with NORDYNE furnace, one flash L.E.D code on the main board "opening on limit switch" so I took limit out of the furnace and stick my thermometer and read 198F (the limit switch limit is 195F) this proves the limit was GOOD! So I checked the evaporator, filter and the vents all around the house and they where GOOD as well! I also checked the gas pressure to be good. I found out that the furnace will heat lower "189F" with out the air filter! (the air filter is new) IN CONCLUSION FURNACE IS BAD!