I have a 15-20 yr old Bryant AC/gas unit and three times in the past 24 hrs it has failed to light. First time, turned off and on 120v at furnace(its on a std light switch), it went through a purge then fired and worked about an hour. Second time it failed I did nothing, and after a while the controller was flashing "Er" (error I guess), after 30+ mins of that it just fired and worked fine all night until now. Third time, turned 120v off and back on an fired like the first time.

Any of you HVAC guys have any insight?

 

Im a Plumber/HVAC guy. Im willing to bet that its a dirty flame sensor. Check by the pilot...there should be another pointy sensor next to it. Take a piece of sand paper and clean it off. What is happening is....the furnace isnt sensing a flame so it is shuting the gas valve. If you have anymore question pm me and ill walk you through it. Also if it is a high eff. furnice...check the drains on the unit. If any drains are plugged or running slow it will kick the furnace off on a high limit switch. These both are very common problems.

 

Thanks. It has an ignitor thus no pilot light. After I climbed up for a better look, it has a LED diagnostic code system with a chart on the side. I'll check that out next time it fails and let you know.

 

There is still a flame sensor on it though. They are very sensitive so make sure it is clean. Pm me if you have any problems.

 

Well, I cleaned the flame sensor with a small file (couldn't find any sand paper handy). It didn't look dirty, but we'll see.

 

There has to be a squirrel in the vent pipe

 

A girble maybe...But a squirrel? Ouch!

 

Only scotch brite or steel whool! With a file???????

BTW flame sensors even when they look clean might still be dirty. It only takes a slight film. I know BS right? My FIL is a HVAC guy. Once a year it is a good idea to clean the flame sensor.

 

It's worked fine all day. It was a very small detail file. I moved and all my shop is in storage. I had to make do.

 

Still chugging along fine. Thanks for ya'lls help!