Why you can’t really clean a sail switch

[ChuckS]

I often see folks saying they cleaned their furnace sail switch and then the problem returns after a period.. These images are from my Suburban SF42Q furnace.. the sail switch internals are the same for the Dometic Atwood furnace..

Spraying contact cleaner or any liquid on this switch will just make matters worse.. the contact points and pivot points inside the case of the switch (that you can’t get to) will just get loaded up with more crap

This case cover is Not Sealed.. the area where the sail switch blade arm pivots at has a gap that will allow dog hair, dust, moisture, etc to mitigate inside the switch

The contact points are very small and once the switch starts having issues making good contact on the two point contact surfaces then pitting will begin and the contact points can’t conduct electricity to complete the circuit the furnace control board needs to see..

This being said often some lint, dog hair, etc can work it’s way in between the body of the sail switch case and the blade arm that needs to move to press down on the plastic contact point.. you could clean this with air but what’s inside the switch and what do those contact points look like?

If I pull my furnace for a sail switch problem the switch is getting replaced.. so far my original sail switch has seen 9 years is use now with no issues.

But I also run my furnace once a month for a few minutes to exercise the components within it and blow out the dirt, dust, leaves, moisture from within the combustion section

[dutchmensport]

I replaced a sail switch only once. Never could figure out why it started failing. But the replacement has run flawless ever since.

Sometimes things are just meant to be replaced. But hey, nothing wrong with dickering around with something. If you can get it working again, it saved you a couple bucks. If you couldn't get it working, nothing lost considering it was already broken to start with.

[ChuckS]

Originally Posted by dutchmensport

I replaced a sail switch only once. Never could figure out why it started failing. But the replacement has run flawless ever since.

Sometimes things are just meant to be replaced. But hey, nothing wrong with dickering around with something. If you can get it working again, it saved you a couple bucks. If you couldn't get it working, nothing lost considering it was already broken to start with.

If my fifth wheel had an outside full access panel to the front of the furnace unit like many other units have then it would not be an issue to tinker with things.. But with a furnace that is mounted under the floor with access only via basement if I pull the furnace once I had TS and verified the issue at hand if its a part the the part is getting replaced..

I am also glad that I don't have an Atwood furnace..

[Bustinbeards]

I agree on just replacing the switch. I don’t like intermittent problems that come and go when you need something to work 100% of the time. if I am going through the process of removing the furnace, although not very difficult in my case, it’s not something I want to do routinely. An access panel might be create an easy way to access the furnace and switch, but you still have an unreliable intermittent part and problem to hassle with.

I know from talking with dometic when I ordered my switch, they redesigned the bracket for the new sail switch. Not sure if they redesigned the switch or not. But the new switch and furnace has functioned flawlessly since I installed it. So apparently dometic address a design deficiency or flaw in the old switch and bracket set up and fixed it and are using an updated part to cure the issue.

I did keep the old switch for some reason though, but I have not done a Postmortem on it like chuck to assess what the problem is with it.

[Balvar24]

I don't believe that was manufactured with cleaning in mind, rather replacement.

[ChuckS]

Originally Posted by Balvar24

I don't believe that was manufactured with cleaning in mind, rather replacement.

It wasn’t and I wouldn’t .. but I see post all the time from folks saying they cleaned the sail switch or the RV Tech cleaned the sail switch.. the point is … No.. they didn’t clean anything if they didn’t drill out the rivet on the case and gain access to the insides of the switch

[RTKRussell]

Originally Posted by Balvar24

I don't believe that was manufactured with cleaning in mind, rather replacement.

The sail switch for my 2021 Dometic DFMD30131 furnace is serviceable. I took it apart, cleaned the 2 contacts (removed the blackened electrical arc corrosion) I did not use a liquid to clean the contacts. Furnace now works perfectly!

[ChuckS]

Originally Posted by RTKRussell

The sail switch for my 2021 Dometic DFMD30131 furnace is serviceable. I took it apart, cleaned the 2 contacts (removed the blackened electrical arc corrosion) I did not use a liquid to clean the contacts. Furnace now works perfectly!

The switch is serviceable provided you have the skills and knowledge.. The video was made to educate folks that are getting ripped off by service centers and such that say they clean that switch instead of replacing it...

** Which is what I will do and would do considering I have no outside access to the front of my furnace... ( No Alpine does )

[jsb5717]

I have often recommended cleaning the sail switch based on my own experience. But it's only superficial. I have experienced lint impeding the function of the switch and by simply blowing it out the switch works again as designed.

Any more than that I fully agree that attempting to do a deep clean won't yield the desired result. Yes, it's much easier to just replace it and that would also be my recommendation if the switch were otherwise free of debris.

If the furnace failure is pre-ignition then the sail switch is a viable culprit and should be inspected and replaced if faulty.

I'm curious, though, about your view of the better furnace. I do have the Atwood with outside access. I find it very easy to inspect and troubleshoot. In our opinion and experience, what makes the Suburban a better furnace? I have little to no experience with them.