Onan summer and winter setting

[Crank]

I was quite confused when I regarded my 1995 Onan and saw on the the top right- hand cover of the air filter cover a large arrow pointing to its corner and the words "pull out for summer, push in for winter".

Photo here: http://www.redroverroadtrek.com/Onan.html

At first I thought it meant to pull out the cover, because I could see nothing to push/pull. A careful look revealed a thin, none-too stiff wire at the very top of the filter housing and just to the right, set back a little: evidently it is what should be pulled or pushed.

Unfortunately it is stuck, (in the summer position), and it is too tight back there to see or feel what might be causing the adjustment to stick. I found some good photos in a PDF file, but I don't have a record of where they came from, nor can I easily extract a photo. One however, shows the wire going straight back 4-5" perhaps, where it operates a rotating toggle, so turning another wire at right angles to the first that enters a metal casing behind the air filter (nowhere near the carburetor) and looks as if it might operate an air valve.

Pushing too hard is just going to bend the wire. But access to to the one moving part I see in the photo looks about impossible.

I sure don't want to have to drop that genny - in fact I won't! So now what?

I'd like to know what this adjustment does, if it is essential, and get ideas about how to fix it. Do people actually USE this thing?

[mlts22]

I've read a lot of Onan posts, and this is the first time I've read about a winter/summer setting. The only advice I might be able to give would be to get with a marine or RV tech to see what to do, preferably someone that has been working on this stuff for a while.

[Crank]

I rather suspected that not many are aware of this adjustment, or understand it. But the indication of its location on the air filter cover can't be missed! See the photo referenced in the OP.

However, I'm sure someone here has had an Onan 2800 on the bench and has examined this adjustment. I just have to wait.

[stanw909]

I've had mine out and on the bench to replace my carburetor and still don't underestand how it works but mine runs great now. I'm not sure who is going to lay down under the van to change it much. Altitude setting for me is more important and I just split the difference but then again I live in SoCal so no winter here.

[AK49er]

According to my Onan manual it is air preheater lever. Use the winter setting for temps below 40*, on temps between 40 and 70 the lever can be left in either position. Temps above 70* require the summer setting. Running the generator in temps below 40 with the preheat lever in summer mode will cause the motor to run rough, stop running or over rev due to icing. Running the Onan in temps above 70* while in winter mode will cause erratic operation reduced power and reduced engine life.

This is similar to my Stihl chainsaw in that I have to turn my baffle from summer to winter mode in temps like Onan suggests. It also prevents icing in those temps.

Hope this helps.

[Crank]

Thanks Ak, that info is very helpful indeed and makes perfect sense. Not in my manual.

I don't know how I am going to free up this thing, but in the meantime it seems I am good for temps above 40F. I doubt I will need the generator below 40F, even if I am camping at that temp - until the time that I do

[Crank]

I took another look at this problem a few days ago.

The adjustment lever is so hard to spot, so small and hard to get a grip on, that it is not surprising that no-one seemed to have experience of it.

This time, when I tried to operate it, I realized that it DOES have some movement, just very little. About a millimeter or two in and out. That I was not imagining thing was confirmed by detecting the "feel" of a slight click in both directions at the end of the rather firm movement.

Who would have thought that this puny wire would offer resistance, yet decisively move such a tiny amount?

Crank

[fwdanielson]

The wire is so thin that it tends to get bent by people attempting to move it in the wrong direction. When I had mine out I straightened it with some pliers and sprayed some wd40 on it to loosen it up. The top straight part of the wire rides in a groove on plastic housing and operates a flap. You could try spraying some lube or cleaner up there and gently work it in and out as straight as possible.

Like so many other things the fix is easy if you pull the generator out. I wouldn't go through the trouble of pulling the unit for that repair but keep it on the list of things to do if you ever do pull it.

[Crank]

Welcome to the Forum, FWD.

Your advice and knowledge is appreciated and useful: thanks! There is not much info on this control, so getting it all together in one thread is useful. No-one wants to pull out an Onan just to deal with this thing!

Crank

[fwdanielson]

Here are some pictures that may help. The original uncropped higher res images are also on a Google photo album that can be found here - https(colon)(slash)(slash)goo.gl/photos/bVReJQoJrhrRsyKd7

The first shows the linkage in the summer setting pulled all the way back. Notice the black lever that controls the flap is pointed out in the same direction as the pulling action.

The second shows the linkage in the winter position pushed all the way in. You'll see a slight curve where the rod had been bent which prevented it from being pushed in. The picture is post straightening and cleaning and now the rod pushed in with reasonable effort. There is a crimp or flat spot in the rod which is what makes it "click" in to the summer or winter position.

The third picture is a view from the inside of the airbox showing the flap in winter position covering the fresh air passage in the back of the airbox and uncovering the air horn which draws warm air from around the generator.

The fourth picture illustrates the airflow in the winter position with the clever use of on index finger and the last picture is the same index finger from inside the air box.

If you are having trouble moving the rod to winter position on your generator I would get a can of wd40 or carb cleaner and give a couple squirts up on top of the rod along with a a squirt or two in the air horn to loosen up the flap's pivot points. Then with a wooden dowel or long screwdriver you should be able to push on the flap with your right hand while gently pushing in on the rod with your left hand. The idea is to get the flap to move without pushing on the rod so hard that it bends. With small hands, one of those red plastic extension tubes on the spray can, and a suitably long push stick this operation should be able to be performed in the vehicle through the access door.

[mccormack.john@att.net]

fwdanielson, Thank you for the excellent information. My Onan 2800 Microlite is now fixed & ready for the winter (when it arrives). You saved me a lot of time & grief.
Thanks again

[Lakeboy]

Thanks for the post. I have been trying to figure out if my Onan 2.8KVFA26100J even has this feature. Its in my owners manual but have not found the lever yet. Hoping someone can shed some light for me. Just bought a 2001 Dodge Pleasureway Excel RD after selling our 40 ft Tiffin Allegro Bus, big change. Lakeboy, Emma Lake Sask Canada soon enroute to Mazatlan for the winter.

[fwdanielson]

Originally Posted by Lakeboy

I have been trying to figure out if my Onan 2.8KVFA26100J even has this feature.

It should have the air pre-heater flap and control. Here is a picture facing the generator airbox and carburetor. The airbox says "Air Pre-Heater Push in for winter Pull out for Summer" with an arrow pointing towards the linkage you pull or push. The linkage is visible in the picture mostly because I am looking up at a slight angle. If you are looking down you may not see it. Pull means pull straight out away from the generator and push means push straight in towards the generator. The full size picture has been added to the others in my Google Photos album at https://goo.gl/photos/bVReJQoJrhrRsyKd7
Onan Microlite 2800 Airbox Front View.jpg

[Lakeboy]

Thanks so much. My air cleaner cover does not have the wording on it for air pre heater. I just took another hard look and feel and found nothing there. Kenn

[Lakeboy]

Hi again. Put a heater on the unit with cover off for 15 minutes, it fired right up, ran smooth and after warmup powered the AC, micro wave etc. This has been going on for a couple days and the heater seems to be the answer. May have to install a 12 volf heater until we get further south, its 6 degrees celcius here right now. Kenn

[fwdanielson]

Originally Posted by Lakeboy

Hi again. Put a heater on the unit with cover off for 15 minutes, it fired right up, ran smooth and after warmup powered the AC, micro wave etc. This has been going on for a couple days and the heater seems to be the answer. May have to install a 12 volf heater until we get further south, its 6 degrees celcius here right now. Kenn

The air pre-heater gets warm air from the generator engine running and does not have any effect during a cold start.

Is the generator propane powered by any chance? Propane units do not have the air pre-heater flap because the they are not susceptible to carburetor icing. If it is a gasoline generator then the choke may not be operating correctly. When the generator is cold the choke flap should close and then open up as the engine warms up. I don't have any good pictures of that mechanism.

[Lakeboy]

Originally Posted by fwdanielson

Here are some pictures that may help. The original uncropped higher res images are also on a Google photo album that can be found here - https(colon)(slash)(slash)goo.gl/photos/bVReJQoJrhrRsyKd7

The first shows the linkage in the summer setting pulled all the way back. Notice the black lever that controls the flap is pointed out in the same direction as the pulling action.

The second shows the linkage in the winter position pushed all the way in. You'll see a slight curve where the rod had been bent which prevented it from being pushed in. The picture is post straightening and cleaning and now the rod pushed in with reasonable effort. There is a crimp or flat spot in the rod which is what makes it "click" in to the summer or winter position.

The third picture is a view from the inside of the airbox showing the flap in winter position covering the fresh air passage in the back of the airbox and uncovering the air horn which draws warm air from around the generator.

The fourth picture illustrates the airflow in the winter position with the clever use of on index finger and the last picture is the same index finger from inside the air box.

If you are having trouble moving the rod to winter position on your generator I would get a can of wd40 or carb cleaner and give a couple squirts up on top of the rod along with a a squirt or two in the air horn to loosen up the flap's pivot points. Then with a wooden dowel or long screwdriver you should be able to push on the flap with your right hand while gently pushing in on the rod with your left hand. The idea is to get the flap to move without pushing on the rod so hard that it bends. With small hands, one of those red plastic extension tubes on the spray can, and a suitably long push stick this operation should be able to be performed in the vehicle through the access door.

I still cant find a lever on my unit and the air filter cover doesnt mention it either. How can I access the photos you noted? Thanks Lakeboy

[Lakeboy]

Hi again from the cold north (8 degrees celsius) Still have issues with 2800. It apparently never had the winter summer lever on this model. It will only start and run cold with the switch being held. I put an in car heater on it for 20 minutes and away it gores. It is powering the heater and still showing 118 volts at a receptacle. What is the heat issue and how do I fix it? The carb is ob viously clean now so I assume its choke/governor related. Any thoughts or suggestions. I know Cummins/Onan will slap another carb on it but it has already had 3 carbs replaced. Thanks Lakeboy