It's not iginting just blowing cold air. It turn on OK this morn and reach the temp set at but the blower kept running blowing cload air. The trubleshotting light flaces 4 times then pulses which means heat sensor switch open/open high limit device. What can I do?

I have a 3DHB12N07501D York gas furnace and it is combined with a heat pump. I noticed the Gas furnace was not kicking in. So after poking around I found the light on the board was blinking 4 times. The panel says it's the high Aux or Spill limit is open. First off I do not know what High Aux would...

Thanks for your input. I finally was able to reverse the wiring and got it squared away. While I was in the attic I thought I would replace the motor which drives the fly wheel. I thought I was a hero till I put everything together and discover 4 flashing lights. The lights indicate "open high...

Furnace is about 13 years old... we just replaced the ignighter in it last night because it was running through all the steps to run except ignighting. It fired right up and ran for about 7-8 hours... now it won't ignite at all (it is running through all the steps it needs to except for...

We have an Ultra V Tech 80 furnace. Cold air is coming out and the ignitors are not lit. Light is blinking 4 times which means high limit open. Where is this at? What needs to be done?