Onan Gens But No Juice

[Volunteer]

I have an Onan NHM, Model #6.5.NHMFA26116F in my 1996 Discovery. I overloaded it last Winter with too much electric heat and a simple re-set of the breakers wouldn't get it producing electricity again.

I installed a new 30-amp and a 20-amp breaker yesterday, thinking I had fried the old ones. But no luck.

I also have a new bridge rectifier in my hands but the more I read, the more I believe this particular Onan doesn't have a bridge rectifier. Can anyone confirm that? If it does, is it behind that plastic grill near the slip rings? I looked in there but didn't see the square rectifier I was looking for.

I'm not smart enough to know where to use my volt meter to see if the generator is even making electricity so for all I know, my problem could be the transfer switch. Of course, I don't know where that's located either. I would guess back near my converter, charger, inverter box???

Bottom line ... do I have a bridge rectifier in this model Onan and if so, where is it?

[RV Wizard]

I would recommend you determine if the generator is producing before throwing parts in it. There are a couple of ways to determine if it is putting out voltage. Find the transfer switch and remove the cover, start the generator and check with either a volt meter the line (black and white) marker generator on the transfer switch or use a voltage sensor tester that beeps and blinks when ac current is present.
If you have power coming from the generator you do not need to try and repair it.
If after a few minutes, you do not get power from the transfer switch into the coach, you have a problem with the transfer switch. Let us now what you find. The more information the better; year, make and model of coach, make and model of transfer switch, etc.

[Volunteer]

Mike, I appreciate your reply. To be honest, I've thought the transfer switch could be the culprit. Could you describe what one looks like?

Although it's not much, here's what I've found: Under my frig, there's the "brain" for my HVAC and behind it is a square metal box with romex (four wires, I think) going into it. There's another square metal box under my bathroom sink with romex (another four wires) going into it. I've presumed all along these were some sort of connectors/transfer switch for my front and rear air conditioners. They both seem to be connected to the floor and I don't see any screws to loosen them from the floor so I can pull them out and open the top. Of course, I haven't tried a crowbar yet.

I have a very experienced 1996 Fleetwood Discovery which is beginning to show a few of these little problems ... much like it's owner. <g>

I will add that when the Onan was working, I could hear it "kick in" after half a minute or so and "load" itself. That was my clue I could turn on an air conditioner. Now, the Onan starts right up but never "loads" ... if that's a good term. In other words, it never sounds like it's working or producing a load like it used to.

I hope this is enough to get some more feedback from you. Primarily, I hope someone knows where the Onan transfer switch is located on a prototype Discovery. (1996 was the first year Fleetwood produced them)

[GaryKD]

Hi Volunteer,
If you have a transfer switch it is usually located in the same bay as your shore power cord. To determine if you have a transfer switch:
1. If to power the coach from the generator you need to plug the shore power cord into a female receptacle in the electric shore cord bay, the coach does not have a transfer switch.
2. If to power the coach from the generator you need to do nothing with the shore power cord, the coach has a transfer switch.

Somewhere on the transfer switch cover, it should say what it is. The next step is to follow what RV Wizard mentioned in his post.

[Volunteer]

No doubt I have a transfer switch because I do nothing to use shore power or generator power ... except if I want generator power, I turn on my Onan and if I want shore power, I plug in my 50-amp plug. (Yes, the first owner had the system converted to 50-amp and if I have at least 120-volts coming from the shore, I can run both air conditioners at the same time without either one of them shedding)

All I have back in the power compartment is the 50-amp cable hard-wired to the converter/charger/inverter unit and the big fuse box Fleetwood installed above the converter. Inside that fuse box ... aside from fuses ... are two rather large switches which are labeled as battery disconnect switches.

Perhaps I should look under my bed. I know some motor home manufacturers put their generator transfer switches there.

But more input from a possible early Discovery owner would really be appreciated by this old DOI volunteer.

[RV Wizard]

The shore power cord is connected first to the transfer switch. It might be what you are calling "the converter/charger/inverter". Make sure all power is off and you should find the transfer box (could be plastic or metal) and is the first thing the power cord is connected to. Now you could have a junction box at the end of the cord and be connected to A 6 or 8/3 romex cable that will be connected to the transfer switch. It will have 3 large conductor cables feeding it.

[wa8yxm]

Some Onanas if they are not producing electricity will shut down as soon as you remove your finger from the START button. So I'm guessing it is producing electricity.. Now

Have you measured output at the output terminals?

What you need to do now is take that measurement.. I'd use a test lamp, in this case you get a light socket with leads on it (Solid rubber socket with leads Put clips on the leads and a small incansadant bulb in the socket, say 10 watt (the little golf ball size bulb) and clip to the generator's output leads. Crank it up and see if you get light.

now move to the ATS generator lines (If you have an L-1 and L-2 pick one and ground, actually we will use both

Again crank it up and look for light

If you have light on both L-1 and L-2 to neutral.. and no output to house. you blew the ATS, same as I did

[Volunteer]

Thanks for the continuing input. I really appreciate it.

Although the access door only makes about a 12" X 8" opening, I got a light, wiped off dust, and found two intersting items underneath my refrigerator where the Intelletic "brain" is located for my two furnaces and air conditioners.

One box is labeled, "Genset Relay Delay - Intellitec - P/N 00-00331-000 - Air Conditioner Loads." It has three Romex wires going into it. I figured this was the ghostly transfer relay.

However ... another box is labeled, "Transfer Relay Delay - P/N 00-00331-000 - and the three Romex wires going into this box are labeled Load - Shore - Genset." This must be the generator transfer switch.

This morning, I disconnected from shore, cranked up the Onan, then beat upon both of these boxes with a hammer. That didn't knock anything loose so tonight I'll take the cover off the box labeled "Transfer Relay Delay", crank up the Onan, and check to see if I have voltage on the leads attached to the Genset connector. At least that will help narrow down my search for the problem and hopefully give you folks who know this stuff a bit of ammunition to help me further.

Thanks again for the continuing input.

[Volunteer]

Now I'm really confused. (I know, I know ... what's new?)

I took the covers off those transfer relay delays under my refrigerator and they were identical. And there were three of them. And they each were rated at 13-amps. The printing on each cover was NOT identical but the circuit board inside each one had the standard ground bar, and a hot and common connection each for, "Genset", "A/C", and "Shore."

You delay relay experts please help me with this situation: None of the three Genset leads had power when shore power was disconnected and the Onan was running. BUT when shore power WAS connected, two of the transfer delay relay Genset leads had 120-volts and one transfer delay relay Genset lead showed no voltage. My simple mind tells me that two of these relays were leaking voltage backward to the Onan while one was not. Right? Or wrong?

Bottom line, there is apparently still a main automatic transfer switch I haven't found. This weekend, I'm going under the bed box and around the power connection to see if I can find that puppy and verify if it is or is not getting electricity from the Onan. Of course, that's presuming the three transfer relay delays I checked last night are downstream from the one I'm searching for. The elusive one should be rated at least at 30-amps. Right?

No wonder those of you who work in the RV repair business have to charge so much for an hourly rate. I don't fault you one bit for that. And thanks in advance for any further input.

[RV Wizard]

The relays you have found are for controlling the shedded circuits from the EMS system; they are NOT the transfer switch. Look for three large cables going into a box.

[GaryKD]

Hi Volunteer,
This is turning into quite a challenge because the coach was converted to 50 AMP service via an after market process. RV Wizard is correct that the transfer switch should be the first box the shore cord goes to. Is is possible for you to contact the previous owner and determine how the coach wiring is set up?

Let us go back to the beginning. Wizard mentioned for you to check to see if the generator is actually putting out power. I do not see in your posts where this has been done. Let's get this step completed first. Somehow, you'll need to find the power wires from the generator. I am not a fan of physically tracing wires, but in this case, that may be what is necessary. When you find the "other" end of the generator wires, take a reading and post here what you find. Just as important, post here what the wires are connected to.

[Volunteer]

I'm losing what sanity I have left in my 66-year old gray matter. Of course, that's not much, but I need every bit I can maintain.

The reason I'm losing my mind is because I can't seem to find the correct automatic transfer switch. Let me start with where my 50-amp cable comes into the Discovery.

And by the way, that inverter/converter/charger I've talked about is a Heart Interface Freedom 20 and has never (knock on wood) given me a bit of trouble.

My shore line stores in the compartment underneath the Heart Interface and first goes into a typical marine-type round 50-amp push and twist to lock connector. I never disconnect it since I have plenty of storage space there. (just an aside)

From the female end of that connector, the cable goes for about a foot, then into a standard electrical box in which is mounted nothing but a female 50-amp plug. Upon taking the front off that box, I see that the female plug is completely bypassed and all four 50-amp conductors are spliced to somewhat smaller pairs which go through the floor and into my Discovery.

The best I can tell, two of those pair go to yet a fourth transfer relay delay under my bathroom sink. This is the same as the three I found under my refrigerator except it seems to be a bit bigger in size (still rated at 13-amp air conditioner load, like the other three) and has two-pair each of Romex going to the "Shore" terminals instead of just one pair like the three under my refrigerator. The other terminals are marked "Load" and "Genset." While plugged in to shore power, I get 124-volts at the "Shore" leads as well as the "Genset" leads. I unplugged from shore power, turned on my Onan and there was nothing at the "Genset" (or other) terminals.

There is single pair of Romex wires coming right beside this relay box and they go into a dark brown plastic box about three-inches long by one and a half inch wide by an inch deep. It's made by Slater Company and is designed to screw into a regular light switch type outlet box. But it's screwed to the floor and has a flat top cover molded as part of the box. If I didn't know better, I would say it was a light switch without the toggle and not even a slot for the toggle to move up and down. Just a Romex into one end of the box and a Romex out the other end.

The best I can tell, all wires then go to the three transfer delay relays I've already described under my refrigerator. I look long and hard under my bed box this morning and there is no transfer switch box under there that I could see.

The original owner passed away and that's how I ended up with this Discovery about eight years ago. While I received all the original manuals and paperwork, there's nothing to suggest where any of these component I'm looking for are located and of course, I can't contact him to get more information.

I can see where the power wire (big and gray and about the same size as my 50-amp shore cable) comes out of the Onan but it exits through a slot underneath the business end of the Onan and I'm not smart enough to figure out how to tell if there's power in it. Tracing it is no good for me because of my bad back and knees.

I'm at wits end with this. What makes it so bad is the fact that my dash air conditioning blows nothing but ambient air. I can't find the fuse that might protect the compressor and/or the condenser fan up between my front wheels. I was going to run my roof air to keep cool while traveling this Summer. But I'm screwed on both cooling points.

So ... if you see a balding old man driving a Discovery down the highway this Summer wearing nothing but sweat and a frown ... honk and wave at me. I'm just trying to keep cool.

[Volunteer]

First, to all who read my last entry just above this one, please accept my apology for the rant. My problems are just that ... mine and I shouldn't be sharing my feelings of "poor me" with any of you, particularly those of you who took the time to try and help me.

Now for the good news (sort of.) I kept poking around up where my Onan is located and found a junction box where the output wires from the Onan are spliced to the wiring that goes on back through my Discovery. I probed the white and the black with my voltmeter, cranked up the Onan, and there was nothing. No juice. So sure enough, my Onan isn't making electricity even though it runs just fine. Further reading tells me the NHM models WILL run without producing electricity.

I've found the only component that has a 12-pin connector inside the control panel enclosure and I'm guessing it is the voltage regulator. It's the same gray metal that the Onan housing is made of and is bolted right on the business end of the generator, near the control panel. There are only about eight inches of wires going from this box to the 12-pin connector.

Going back to my original post that started this whole thread, I'm now thinking this particular Onan has a voltage regular and not a bridge rectifier. Based on the previous paragraph, would anyone agree with that?

The reason I ask is that I've found a replacement regulator but as another has stated in this thread, just throwing parts at a problem is not really cost-effective. I'm not asking for an agreement that I should replace the voltage regulator, but does anyone feel this MAY be the culprit here?

Sorry for this long thread. But I really appreciate all the feedback. While I won't ask for any more help after this, I will come back and let you know what it took to fix this problem.

[Clonetrooper]

Give Fleetwood a call at 800-322-8216, mon thru fri. They will send you/e-mail lots of electrical, plumbing etc schematics. Just give them your model # and vin. They have sent me a lot of info. I have a 99-00 Discovery 38 and remember the transfer switch is under fridge. Will look on my prints to see if there is something else. But if you have no volt out of gen...There is a great RV supply house here in SA. It's called Texas RV Supply at 800-449-8787, closed 30 minutes ago. They have gen control boards for Onans for $183. Give em a try mon. They have alot of stuff there, cattalog is about 2" thick. Fairly reasonable prices too. Post back if you need more help.