Sail Switch Replacement

[Troyvan]

Hi All. We are the recent new owners of a mostly renovated 1975 Trillium. I have been working on the interior finishing details over the past 2 months, enjoying the heat from the Suburban NT-16SE propane heater. I have been plugged into shore power and heater has worked great.
Yesterday, I removed the shore power connection and relied solely on the trailers house battery to power the lights and heater. I immediately noticed that the heater would cycle on for a short time, but at no point did I hear the distinctive “click” of the igniter. I am thinking 2 things:
1. The battery does not have enough power to spin the heater fan sufficiently fast to activate the sail switch, or

2. The sail switch is dirty / defective and requires cleaning and / or replacement.

Wondering if anyone out there could walk me through the procedure to access the sail switch for cleaning / replacement, or, direct me to a YouTube that specifically deals with my Make and Model of heater.
Thanks in advance for any suggestions. Cheers
Troyvan

[Dave Fish]

I'm thinking that if it was working on shore power, then it's more likely to be the battery than the sail switch. I would focus on that first.

We had a problem with the sail switch on our brand new Casita. They took care of it under warranty, but I do know that it was several hours labor just to get if out and inspect it. The fix was a minor adjustment.

[Troyvan]

Thanks Dave. I plan to replace the existing 12v battery with my 2 new 6v golf cart batteries, (in series), later today when the rain lets up. Fingers crossed that solves the issue and will post an update. Cheers

[Raspy]

It is incredibly unlikely that the sail switch failed at the exact same time you unplugged the trailer. The sail switch seems to be the default thing to blame when the heat won't start, but it could easily be a discharged or sulfated battery. Plug the trailer back in and try again. If it works, it's probably not the sail switch.

[AC0GV]

Originally Posted by Troyvan

1. The battery does not have enough power to spin the heater fan sufficiently fast to activate the sail switch, Troyvan

Waving a magic wand never works well, the first step in this is to measure the voltage, and it is MUCH easier than changing the sail switch. All RVers need a volt meter, the 6$ unit at harbor Freight (the one they no longer give away) is fine. If you do not know how to run a volt meter, see the link below. And back to the sail switch, I once had a transmitter fail that needed to be on the air, the plastic vain on the switch had bent over the (20+) years, I turned it around to "cup" into the air flow and it was still on when replaced years later. I do not know how the RV furnace vain is mounted and it may not work on that.
https://smile.amazon.com/dp/B07VN5BB...roduct_details

[Betty R]

Hi-check the fuse in the inverter first!

[Troyvan]

Ok, so I replaced the older 12v deep cycle battery with 2 new 6volt Golf Cart batteries, (wired in series). Battery monitor read 12.9, which I thought was a reasonable / decent charge.
Tried the heater and the same result - Fan ran for about 20 seconds, then shut off, without attempting to ignite. I plugged the shore power in and the battery monitor then read 13.5. Turned up the thermostat; fan ran for about 20 seconds, followed by the ignition “click”, followed by flame and heat.
I am still thinking that the sail switch is the culprit and would love to hear from others if this is something I could tackle; (ie disconnect gas line, remove heater unit, inspect / replace sail switch and reinstall), or if this project is best left to a Service Tech.
Our trailering plans include mostly off-grid locations, so a heater that works soley on the strength of battery power will be essential.
I could not find any YouTube videos that dealt specifically with our Make and Model of heater, but any suggestions from Forum members much appreciated as always. Cheers. Troyvan

[Jon Vermilye]

Originally Posted by Troyvan

Ok, so I replaced the older 12v deep cycle battery with 2 new 6volt Golf Cart batteries, (wired in series). Battery monitor read 12.9, which I thought was a reasonable / decent charge.
Tried the heater and the same result - Fan ran for about 20 seconds, then shut off, without attempting to ignite. I plugged the shore power in and the battery monitor then read 13.5. Turned up the thermostat; fan ran for about 20 seconds, followed by the ignition “click”, followed by flame and heat.
I am still thinking that the sail switch is the culprit and would love to hear from others if this is something I could tackle; (ie disconnect gas line, remove heater unit, inspect / replace sail switch and reinstall), or if this project is best left to a Service Tech.
Our trailering plans include mostly off-grid locations, so a heater that works soley on the strength of battery power will be essential.
I could not find any YouTube videos that dealt specifically with our Make and Model of heater, but any suggestions from Forum members much appreciated as always. Cheers. Troyvan

If the sail switch is dirty, it might be that the higher voltage on shore power is enough to close it. 12.9V is definitely enough to close a properly functioning sail switch. While less likely, it could be the lower voltage doesn't open the gas valve. I'd still check the sail switch first since it is a more common problem, particularly if you have pets that shed.

[AC0GV]

Originally Posted by Troyvan

Ok, so I replaced the older 12v deep cycle battery with 2 new 6volt Golf Cart batteries, (wired in series). Troyvan

Please post what you find, it may help others. Have you checked the voltage right at the furnace? Long shot but worth checking before you pay someone else to work on it. I'd also inspect the sail switch and lube the blower motor.

[Troyvan]

Thanks Jon. Was wondering if you have personally changed / cleaned the sail switch before, or did you have a Service Tech do the job?
We have a Suburban NT-16SE heater. Could not find any YouTubes specifically for that Make and Model, so would be interested in hearing from any Members who have cleaned a sail switch on a similar heater; so that I can get a handle on how easy / difficult the process is.
Thanks

[Jon Vermilye]

Originally Posted by Troyvan

Thanks Jon. Was wondering if you have personally changed / cleaned the sail switch before, or did you have a Service Tech do the job?
We have a Suburban NT-16SE heater. Could not find any YouTubes specifically for that Make and Model, so would be interested in hearing from any Members who have cleaned a sail switch on a similar heater; so that I can get a handle on how easy / difficult the process is.
Thanks

Both. When I was fairly sure I had a sail switch problem I pulled the furnace, discovered a screw the trailer manufacturer left on the compartment that worked its way under the circuit board. Mine is an Atwood AFSAD12 which is now Dometic. The sail switch is on the back side of the furnace. The newer versions of the furnace has an outside access door that gets to the switch & circuit board so you don't need to pull the furnace. Unfortunately, I bought my trailer a year before Escape switched to the outside cover version.

A month ago I was almost sure the problem was the sail switch, but since I didn't have a spare, and was on the road in Quartzsite, I moved to a site with hookups, so I could still run my refrigerator with the gas off, called a mobile tech & he cleaned the switch rather than replaced it. been working since - By the way, he charged $67.50 for :45 minutes of labor.

[Glenn Baglo]

Originally Posted by Jon Vermilye

By the way, he charged $67.50 for :45 minutes of labor.

About half the shop charge anywhere, and he came to you.

[Jon Vermilye]

Originally Posted by Glenn Baglo

About half the shop charge anywhere, and he came to you.

Yea, I found it unbelievable. Just in case anyone needs work in the Quartzsite area, Jeff Kreutzer is a NRVTA Certified Technician and is Blue Line Mobile RV Service, 303 215 1203. Oh, and it took him all of 25 minutes to arrive after I called him. He is not based in Quartzsite, but is here for the winter.

[woodentoy]

Has anyone had success using a small can of compressed air to clean the sail switch in place?

[TZBrown]

It may also be possible that your fan motor bushings need a bit of love. 1975 vintage has seen some use.
Add a couple of drops of good oil to each.

If there was any additional drag from them 12.9 V may not be enough push, but 13+ probably would be.

If you can get an amperage draw on the furnace it may help

[Troyvan]

Thanks everyone for all the suggestions. I plan to check the voltage and get an amperage draw at the furnace later today, (prior to focusing on the sail switch), and will give an update on my findings. Look forward to any other suggestions from the Forum. Cheers

[IMEd]

I installed a filter like this just behind the fresh air intake screen. Never had a dirty sail switch problem.
Simply taped it to the inside framework of the screen.

https://www.amazon.com/Pura-Computer...s%2C126&sr=8-3

[Troyvan]

Hi everyone. I returned to our trailer yesterday in an attempt to check the voltage at the furnace and also do an amperage draw. (Disclaimer- - I am fully proficient at all our trailer repairs and upgrades …. Except for electrical issues). I removed the front cover of the furnace, plus the fridge, so that I had clear access to the front and side of the furnace. (And this is where my electrical inexperience came into play). At the risk of touching the wrong wires with my multimeter, I was stumped on how / where to take the voltage and amperage draw readings. (ie do I need to remove the furnace unit from the cabinet, to get access to the fan motor?)
FYI, our Suburban NT-16SE furnace manual says it was manufactured in 2009 and the amp draw is spec’d at 2.8.
I am currently searching YouTube’s on how to test the voltage and amperage on an rv furnace, however, if anyone has any advice / tips to offer, always appreciated. Thanks

[Troyvan]

Update - I removed the heater from our trailer and have it on my work bench to clean and investigate. Found a small hornets nest on inside of intake chamber, (which would have restricted air flow to some degree). Put a little oil on the fan motor shaft and spun it around by hand. Does anyone know if the fan should spin freely by hand, or does the electric motor hold it back when not energized? Thanks

[Troyvan]

Final Update- - I was able to put a amperage load test on the motor and found that it drew approximately 3.2 amps, (vs the 2.8 amps specified in the Manual). I ran the motor on my bench for 20 minutes , (connected to a 12 volt battery). After 20 minutes, the motor surface went from 22.5 Celsius to 29.1 Celsius. The motor casing only felt moderately warm to the touch after the test.
I cleaned and lubricated the sail switch, plus added a small “flag” of masking tape to the sail, to create a bit more surface area.
In the mean time, I looked online and phoned our local RV shop to enquire if I could purchase a replacement motor. It appears that this motor, (Telco 12v - Part # 232878), is no longer in production and I was not immediately successful in finding a replacement motor.
The lubricated motor and modified sail switch appeared to work well on my bench test, so my plan is to reinstall the furnace tomorrow, then keep looking for a replacement motor in the mean time. It appears that if I am not successful in eventually locating a replacement motor, I may be forced to replace the entire furnace unit. (It is only 13 years old, so am hoping that will not be necessary.
If any Forum members have ahead any success in locating a suitable replacement motor, that would be greatly appreciated. Thanks