[Tanner23456]

My furnace is "short cycling" I believe. Typically the blower will turn on for about a minute and then shut off. After that I can hear the inducer motor running for a few minutes and then the blower kicks on for a normal amount of time to complete the cycle. There have been a couple of times that the inducer motor will run for an inordinate amount of time (approximately 10-15 minutes) before the main blower will finally kick on. I suspect the heat exchanger is overheating but I'm not sure.

What we've done:

- flame sensor was replaced last year
- Pressure switch was replaced last year for a different problem
- Filter is clean
- We cleaned out the vents the best we could

What I plan to try:

- attempt to clean out the inducer motor exhaust
- clean off the flame sensor even though it's new

I could use some guidance from anyone who's willing to give it before this gets worse.

 

[roughneck]

What is the make and model of this furnace? Does it have diagnostic codes? If so what codes are active when this problem happens?

 

[Old Thomas]

The safety devices are usually in a circuit and close when in operating mode. I bypass them with a jumper one at a time. If it runs I know what the bad part is.

 

[user_12345a]

The safety devices are usually in a circuit and close when in operating mode. I bypass them with a jumper one at a time. If it runs I know what the bad part is.

When a safety is opening, there's usually a reason - the part is rarely actually defective.

To check safeties, you use a meter - you don't jump them out!

 

[roughneck]

The safety devices are usually in a circuit and close when in operating mode. I bypass them with a jumper one at a time. If it runs I know what the bad part is.

That is terrible advice to give. And a poor troubleshooting technique to use.

 

[surferdude2]

I suspect you guys are objecting not because it's a bad service technique but because it's a bad idea to tell someone who doesn't fully understand the equipment to use it since they may leave the jumper in place and be sorry.

I have no reservations about using a jumper around a safety device or some other method to bypass it for a quick test occasionally. I just don't want you doing it! :biggrin2:

 

[roughneck]

It’s still not needed. Diagnose with your meter and instrumentation. To start just bypassing things is poor practice.
Plus, many feel open safety’s mean that the switch needs to be replaced or is otherwise “bad”. When the safety is usually doing it’s job.

 

[roughneck]

It’s still not needed. Diagnose with your meter and instrumentation. To start just bypassing things is poor practice.
Plus, many feel open safety’s mean that the switch needs to be replaced or is otherwise “bad”. When the safety is usually doing it’s job.

 

[surferdude2]

It’s still not needed. Diagnose with your meter and instrumentation. To start just bypassing things is poor practice.
Plus, many feel open safety’s mean that the switch needs to be replaced or is otherwise “bad”. When the safety is usually doing it’s job.

I don't think you realize that I'm a lot smarter than you are giving me credit for! :biggrin2:

 

[roughneck]

I don't think you realize that I'm a lot smarter than you are giving me credit for! :biggrin2:

Didn’t say anything about that.
But use your tools to diagnose.