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Aqua Hot Diesel not Firing (Lighting)….2006 Executive. WHY???


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The AH has been working great since I bought the coach two months ago. It had been off for a few weeks. Started it last night and it would not fire up. The AH light at the interior panel comes on for a short time and goes out.  Trouble shooting today, I found the 10 and 15 amp fuses in the front left lower panel good. When checking the status panel, the Heating Status, #2 pump, Diesel Burner and Low Temp cutoff lights are lit up even when the system is shut off at the thermostats. I pushed the reset and it clicked, but no change. After more attempts, I checked the reset and it was not tripped. The burner blower runs as it should then it turns off after a short time . With both master switches turned off, the electronic control board still has power and the above lights remain on. This is my first issue with an AH system so I'm mostly in the dark. any Ideas??   

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A no light condition can be several things: ignition coil, electronic controller, flame sensor, high limit thermostat, fuel pump, electrodes improperly aligned, and a few others.  It's best to work through the Aqua Hot trouble shooting diagram.  

But many times, if it was working well and suddenly quits the flame sensor is the culprit.  And it's the least expensive part to fix.  

Do you have the Aqua Hot manual with the trouble shooting diagram?

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I do not have the manual, but will download it. I was confused with the number of panel lights that were on when everything was off.   

 

I found the manual. While checking some more, All the lights that were on before are off except for the Low Tank Level which is green and not Red. The tank level is ok. Also, the diesel burner switch in the kitchen will not light up when pushed. All fuses that I have found are good. 

Edited by Venturer
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3 hours ago, Venturer said:

I do not have the manual, but will download it. I was confused with the number of panel lights that were on when everything was off.   

 

I found the manual. While checking some more, All the lights that were on before are off except for the Low Tank Level which is green and not Red. The tank level is ok. Also, the diesel burner switch in the kitchen will not light up when pushed. All fuses that I have found are good. 

My take…and AH’s tech support….  SERVICE IT.  That is a new filter and new nozzle and then adjusting the “burner housing” or shroud.  I chose to have a “AH Certified” as in he is listed on the AH site as AUTHORIZED….do the work.  It had been about 3 or 4 years since that was done.  Your symptoms were exactly like mine,  The electric boiler worked great and no leaks and the individual zone regiaters, used ONE AT A TIME, worked.  But when you pushed the Diesel button, the light came on….the recirculation or “stir” pump turned on…but after maybe 5 - 8 minutes, there was NO exhaust smell nor was any hot exhaust air coming out.  In other words….NO DIESEL BURNER was on.  The tech did the standard fix….filter, nozzle, adjust the housing….  Fired it up.  Diesel was fine.  Then tested every zone….all perfect.  He said….you can never second guess the AH. Instead of spending time and effort checking components and such…do the simple routine.  He said that they were told at the AH training classes that fuel condition and the age of the fuel and the condition of the nozzle were all contributing factors.  I HAD changed out the filter….NO JOY.  He said that the nozzles or the sintered portion would “gum up”.  Start and ignite one day….the next day…..NO JOY. 

He said that if the system responded and worked fine, as it should, after the normal PM or Maintenance, that doing all the complex trouble shooting was “trying to fix something” that probably wasn’t broken and that 80 -90% of the rigs he worked on just needed the recommended 2 year tuneup.

That’s my take. We have a LOT of experienced folks…but doing the recommended service should fix it….if NOT, then start to follow the troubleshooting protocols…

 

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Great.  When I said "No Light" I meant the diesel burner isn't lighting.  

Sometimes, you can disconnect shore power and then disconnect the batteries and wait 5 min. 

Be careful disconnecting the batteries.  If you remove the ground first the inverter will try to ground through the RJ11 cord (phone cord) and cause problems.  So, disconnect the battery positive terminal first.  

Then reconnect everything and it will reset the system.   

Good luck!

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I have a service tech coming Monday morning. The system was supposed to be serviced before we picked it up, but will have that checked. Tomorrow, I will also do as vito suggested and see what happens. I had thought about do it anyway just to see if the system would reboot itself. If everything works, I'll still have the burner serviced just to be certain all is well. Thanks to both of you. 

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I have had the same issue with my aqua hot ( going to be serviced next week )  Was doing some inside work on the coach last week had the generator on would not ignite Came back 2 days later drove it about 50 miles round trip for fuel. Parked and tried the aqua hot it ignited blew smoke out of the exhaust for about 10 minutes then cleared and worked fine.

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I don't think it's a fuel issue as I've only driven 70 miles since fill-up. Hopefully a reboot mentioned above will solve the problem. 

Edit: I unplugged the coach and turned the 12 volt disconnect switch for the coach off for 10 minutes. When I turned it back on, the low voltage light and low temp lights came on. The inside panel AH switch also responded turning the burner blower on however, it did not light. Tomorrow, I'll do a complete positive cable disconnect for 15-20 minutes and see what happens.   Hopefully it will be the flame sensor or possibly just servicing the AH will bring it back to life. 

 

Edited by Venturer
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10 hours ago, Venturer said:

I don't think it's a fuel issue as I've only driven 70 miles since fill-up. Hopefully a reboot mentioned above will solve the problem. 

Edit: I unplugged the coach and turned the 12 volt disconnect switch for the coach off for 10 minutes. When I turned it back on, the low voltage light and low temp lights came on. The inside panel AH switch also responded turning the burner blower on however, it did not light. Tomorrow, I'll do a complete positive cable disconnect for 15-20 minutes and see what happens.   Hopefully it will be the flame sensor or possibly just servicing the AH will bring it back to life. 

 

KISS….unless you think you need a spare “flame sensor” or other parts, I’d do or have the servicing done.  Again my “AH Certified” guy and his interaction with other techs at the AH sponsored training seminars is that a new filter, nozzle and burner shroud adjustment…sometimes gently tapping on a motor housing to free up a stuck check valve resolves 80 or maybe higher percent of the AH problems.  Obviously the “reset” and such will help and should be done.  Magnum inverters are notoriously picky once they get abused and the electronic ghosts and gremlins need an hour or so of solitary confinement to “pass on”.  Don’t know about the less complex board in the AH, but it is free….just remember KISS….
 

I am obviously a believer based on mine and discussions with AH tech support and my guy…

Let us know….we all learn

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  • Tom Cherry changed the title to Aqua Hot Diesel not Firing (Lighting)….2006 Executive. WHY???

Thanks Tom. I'm not sure how informed the tech is, however, I will ask him to do a complete servicing of the system before unusual parts get installed. While it was running before, it had a stronger "diesel" smell than our previous coach which leads me to suspect basic servicing might be all that's needed.      

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12 hours ago, Venturer said:

I have a service tech coming Monday morning. The system was supposed to be serviced before we picked it up, but will have that checked. Tomorrow, I will also do as vito suggested and see what happens. I had thought about do it anyway just to see if the system would reboot itself. If everything works, I'll still have the burner serviced just to be certain all is well. Thanks to both of you. 

If it still has the soft rubber intake air boot going thru the floor, ask him / her to discard it.

They can collapse, reducing airflow, and cause a rich burn and sooting!

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1 hour ago, Venturer said:

Thanks Tom. I'm not sure how informed the tech is, however, I will ask him to do a complete servicing of the system before unusual parts get installed. While it was running before, it had a stronger "diesel" smell than our previous coach which leads me to suspect basic servicing might be all that's needed.      

Mine was smellier during the last year before it died.  Regular service fixed it.  Good luck

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Thanks Tom. I checked for the boot Ben referred to. It's already been removed. Looking up into the opening, I see two plates. One covers half of the opening and another one covers 3/4 of the rest. That seems restrictive, but maybe it opens when running.    

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Louisville engineering sells a secondary fuel filter system that filters to two microns as opposed to the original 10 micron filter. There is a narrative by Louisville describing the benefits. Very interesting as the sintered filter on the nozzle overtime will plug because 10 micron filter is too large. Claims the nozzle will last multiple times longer and require less frequent service. Plus the 2 micron filter elements are readily available. I may install when I get the opportunity.

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49 minutes ago, 96 EVO said:

Nobody make a spin-on 2 micron filter that would fit the factory filter head?

The Garber Filters are "Residential" Fuel Oil Filters for furnaces and such. The "Laughing Man" brand was the OEM for Aquahot and is a 10 uM  (Micron) filter. The "R" was RESIDENTIAL....they have changed that to "G" or presumably GENERAL as it is the defacto standard for the AquaHot.

Don't know what size or SAE or whatever spec there is for the "head" or housing...  

FWIW....  Your engine filters are the same as mine.  The main FUEL filter is the FF5636.  It is a 5 uM (Micron) per the spec. The Water Separator filter is a FF5636. It is rated at 10 uM (Micron). 

I am a bit skeptical of WHY one would need that small a filter....seems to me that the pressure drop, based on the Aquahot's pump might be restricted...

If we needed a 2 uM filter, then why would AH use the 10 uM.  One COULD be a Conspiracy Theorist and think that Aquahot wanted one to have to change the filter less often, but would need the unit adjusted and serviced.  Based on what I know or read...and my experience is limited, the constant vibration of the shroud is one of the "weak points", so if you have it serviced on a 2 - 3 year cycle, then the shroud is readjusted.

I know that I got over 4 years....and it was "smelly" but it worked. I have had mine serviced Three Times... and it is a 2009.  The first time was in 2013 and it really, per John Carillo, was NOT that bad (ABQ Balloon Fest). I had it serviced later 4 years later....and then it needed it again in 2022....but it stopped working in 2021. 

So... I pushed it....  Not sure why one wants an add on...  I do NOT think that the two AH experts suggest that either...but SOMEONE will probably ask......

EDIT.

IF you do a lot of research, the 2 micron filter is part of a FASS system. The oil heating (that is what we have) systems think that the Garber 10 uM are the Cat's MEOW and if you have enough garbage or sludge in your tank, they recommend a much larger filter to pre filter otherwise you will plug up a 10 uM filter.

The 2 uM filters are designed, if I read correctly, for high pressure, high flow applications.  I did NOT find a filter that was a low pressure residential one like our AH's are.

In addition, the 2 uM are recommended for high service or continued duty. My AH guy said that if you ran the AH a lot, then the amount of "GUNK" or residue that builds up would be, like a fuel injector, flushed out. It is the NOT IN SERVICE time that allows the diesel to sort of "get gunky" and plug the Sintered backside.

That's my take....hope someone bites and calls AH and asks them....

 

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Before Aqua Hot switched to the Garber R spin on ( which is a nice filter for an RV, because they are epoxy coated on the inside and don’t rust) they used the the Parker/Racor R12T system which is a cartridge style. The system Louisville Engineering installs and sells is the Parker/Racor R12 with an R12S element 4 micron after the fuel goes trough the original 10 micron. They let the original Garber R filter the big particles before the R12S. As for as changing anything Aqua Hot did originally, keep in mind these are the same design engineers that still today mount a burner control module under the cover cooking at 185 degrees even on 100 degree days with the Aqua Hot turned off.

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41 minutes ago, radioman said:

  As for as changing anything Aqua Hot did originally, keep in mind these are the same design engineers that still today mount a burner control module under the cover cooking at 185 degrees even on 100 degree days with the Aqua Hot turned off.

Your right!

I started leaving my front cover off to reduce heat buildup in there. I was chatting with a AH qualified repairman working on a coach next to myself, and told him I was leaving the cover off. He tells me if the AH catches fire with that cover off, my insurance won't cover me!

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Update: The tech confirmed there is spark but no fuel. When he jumped the controller SG 1553/12V, there was fuel at the nozzle. He's checking with his source to confirm the controller is bad. It's a Holiday today, so might not know till tomorrow. I located a replacement online if needed. $429 plus shipping.  We just might get it running so we can go to Quartzite on Sunday to learn more about this Monaco.    

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3 hours ago, 96 EVO said:

Your right!

I started leaving my front cover off to reduce heat buildup in there. I was chatting with a AH qualified repairman working on a coach next to myself, and told him I was leaving the cover off. He tells me if the AH catches fire with that cover off, my insurance won't cover me!

You can extend the B and C cable thru the big  grommet on top and mount it outside the enclosure and put your lid back on. Louisville Engineering makes a plug and play cables to do this. In full disclosure I should point out one of the owners is my dad and I worked for them in the summer before I was commissioned into the Navy.

 

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4 minutes ago, Venturer said:

Update: The tech confirmed there is spark but no fuel. When he jumped the controller SG 1553/12V, there was fuel at the nozzle. He's checking with his source to confirm the controller is bad. It's a Holiday today, so might not know till tomorrow. I located a replacement online if needed. $429 plus shipping.  We just might get it running so we can go to Quartzite on Sunday to learn more about this Monaco.    

Good (or maybe BAD) NEWS. You have identified the problem. So, go from there. Louisville Engineering has several good comments from posts here. I can't say anymore other than pass that along...  They refurbish and repair boards and DID make up a custom harness to defeat some crazy voltage problem that was shorting out the board...so they seem to know their electronics. I can NOT verify or comment on the lifespan of the boards.  But the member went through 3 boards...  It was EVENTUALLY, we think...based on several offline comments with some experts) a PUMP (circulating issue). The member also changed out that pump with a REAL AH model (Used...eBay) and AT THE SAME TIME....installed the Bypass or Isolation relays and harness that Louisville provided.  THUS, it worked and their board was fine. We could SEE where the board POPPED and it was on the PUMP START circuit.  That circuit is on the PCB and is NOT separate wired...

SO...just an alternative...but again....we have had maybe 5 folks speak positively about Louisville Engineering...but there are TWO main suppliers....  John Carillo and Roger Berke are the GO TO GUYS... 

https://www.heatmyrv.com/

https://www.rvhydronicheaterrepair.com/

Good Luck....

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After jumpering you got fuel at the nozzle so fuel solenoid is okay.  Another common thing that prevents the fuel solenoid from opening is the high temperature cut off.  If your controller is cycling the motor and starting the sparking cycle ( you should be able to hear it spark a few times ) and then detecting no flame and doing a shutdown cycle I might think the controller is okay but the safety temp cut out has failed thus preventing the fuel solenoid from opening so there is no fuel for the spark to ignite.  Anyway did your tech verify the temp cut out was functioning?  As I recall the electric and diesel temp probes are the same on some units and thus could be swapped to diagnose.

FWIW

Edited by amphi_sc
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Something I have that is very quick and useful for troubleshooting is the aquahot webasto test box. It plugs in as the burner control does. It will test fuel, ignition, blower and flame sensor on my ahe100-04s. If these test ok there is nothing wrong in the burner . Then next would be the burner control box suspect. A spare new burner control is nice to have. As is a spare circuit board.  Aquahot service is very expensive if done at a shop. The box soon can pay for itself.

.glad to see Roger Burke site comes up now. For awhile it looked like he had vanished. William Barie of Louisville engineering is a member of this site also.

Edited by Jetjockey
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