Author Topic: Aqua hot diesel and electric not working  (Read 812 times)

Don White

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Aqua hot diesel and electric not working
« on: November 20, 2021, 03:24:47 PM »
Hi,

I have a AHE 100 04S Aqua hot unit in my 06 Marquis.  Yesterday morning I switched it from diesel to electric.  After doing so neither is working.  There is no hot water or heat.

I checked all the circuit breakers, coolant level and controller board for fault indicators.  All are fine.  The zone pump motors work fine.

Per the shop manual I went through the troubleshooting section which pointed to the diesel controller being defective.  I ran through the checks on page 68 to test the controller.  The 4th test failed which is the VDC High Limit Thermostat test.  All tests after that failed as well, Motor Circuit Test and Ignition Coil Circuit Test.

2 questions.

1.  Should the results I got, failure of all the down stream tests after the failure of the VDC High Limit Thermostat Test, be expected?  The Motor Circuit Test and Ignition Coil Circuit Test failed because of the upstream failure of the VDC High Limit Thermostat Test and not necessarily because they are bad?

2.  If the diesel heating side fails for some reason does that cause the electric heating element to stop working as well?  Is that normal behavior?

Thanks for any insight or suggestions in advance.

Don

 
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Frank Bergamo

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Re: Aqua hot diesel and electric not working
« Reply #1 on: November 20, 2021, 04:07:20 PM »
Don,

There is a low voltage reset button on the control panel. https://www.ebay.com/itm/264803663371
Try resetting the button with a non metallic pointer or a toothpick. If that does not work, turn off battery disconnect switch to reset system. Hope this helps.
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Stan Simpson

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Re: Aqua hot diesel and electric not working
« Reply #2 on: November 20, 2021, 06:18:41 PM »
When you say diesel controller, are you talking about the Webasto plug and play controller (picture attached)? If so, they do fail. Aqua Hot has them for something North of $850. When mine failed, I got it through McCoy Freightliner in Brooks, OR, for $567 which included shipping to Florida. That was in 2015, so prices are probably much higher now.

Picture 1 - Old one
Picture 2 - New one
Click on picture to enlarge
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Fred Brooks

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Re: Aqua hot diesel and electric not working
« Reply #3 on: November 20, 2021, 06:33:54 PM »
   Don,
The DC hi-limit is a safety device that once it senses an issue, opens the circuit. Everything down stream of that device will not work. According to the t-shoot guide, you can temporarily jump the limit switch to check out the rest of the system. Do this first then see where that takes you. Hope this helps, Fred Brooks
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Don White

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Re: Aqua hot diesel and electric not working
« Reply #4 on: November 20, 2021, 07:26:29 PM »
Hi Fred,

I just want to make sure I'm understanding what you are telling me.  According to the service manual I'm looking at if the controller fails the VDC High Limit Test the controller is bad and needs to be replaced.  Are you saying that the reason the controller test failed is because the thermostat is bad?  Please let me know and thanks.

Don White
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Don White

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Re: Aqua hot diesel and electric not working
« Reply #5 on: November 20, 2021, 07:47:26 PM »
Hi Stan,

Yes, I'm referring to the diesel controller.  I did find that my unit, 287.962, has been replaced by a newer model.  I have located one for $500.  Thanks for the info.
Don White
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Eric Maclean

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Re: Aqua hot diesel and electric not working
« Reply #6 on: November 20, 2021, 10:12:44 PM »
Stan
The t shooting guide is telling you that the controller sends   voltage to the high limit switch so yes if there is no voltage present on one side of the high limit switch you have a controller problem the high limit switch is installed and set at 230 degrees if the temperature goes above the 230 degree the high limit switch opens removing power to the controller circuit to shut it down avoiding a runaway condition if the high limit switch is open the rest of the controller tests will fail
I agree with Fred at this point by pass the high limit switch to test the diesel operation ( keep an eye on the temperature as the primary thermostat may be faulty which may be the cause of the problem.

If the high limit switch in open it has likely seen too high of boiler temperature causing the condition
Remember that the electric side also shares the same boiler fluid if the boiler over heats both high limit switches diesel and electric will go open the old style limit switches would reset but the newer ones don't

The bottom line is that the boiler has likely suffered an over heat condition and all 4 of the thermostats should be replaced to guarantee that they are accurate and working properly.

I don't think you have a controller problem at all

Hope this helps
Eric
« Last Edit: November 20, 2021, 10:19:09 PM by Eric Maclean »
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Fred Brooks

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Re: Aqua hot diesel and electric not working
« Reply #7 on: November 20, 2021, 10:27:04 PM »
   Don,
Eric could not have said any more clearer what I am trying to share with you. If you have no continuity thru the VDC hi-limit t-stat that is your fail safe so you don't have a "run-away" condition. Call Aqua-hot at 800-685-4298 and they are really great at guiding you. Fred
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Eric Maclean

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Re: Aqua hot diesel and electric not working
« Reply #8 on: November 20, 2021, 10:57:50 PM »
Don
To be clear the high limit switchs are there to keep the boiler from running away if a primary thermostat fails to control the temperature if you choose to by pass the high limit switch s be careful as the primary thermostat that caused the run away conditions may do so again .
The by pass must be looked at as a temporary thing to diagnose the rest of the system.

A run away boiler can become a time bomb if left to run away the temperature and pressure can cause a dangerous super heated steam situation.

Eric
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Don White

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Re: Aqua hot diesel and electric not working
« Reply #9 on: December 05, 2021, 07:07:06 PM »
I want to thank everyone for their input on my problem.  It turned out to be the primary thermostat was bad.  According to the technician who replaced it when he applied anti seize compound to get the old one out of the tank the thermostat fell apart from corrosion. The service shop did run a check on all the other components, and they checked out fine. A new primary thermostat was installed and the system, both diesel and electric, fired up fine. 

I had the work done at Eagles Pride at the Great Outdoors on the Space Coast in Titusville FL.  They seemed to know their way around Aqua Hots.

Thanks again for the information and help.

Don
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Eric Maclean

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Re: Aqua hot diesel and electric not working
« Reply #10 on: December 05, 2021, 07:39:19 PM »
Don
Are you staying in or are around Titusville area  or are you just moving through.
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Don White

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Re: Aqua hot diesel and electric not working
« Reply #11 on: December 06, 2021, 11:41:14 PM »
Hi Eric,

My wife and I full time in the coach.  We have a lot with a port in Willow Lakes RV resort in Titusville that we stay at when not on the road so it is our home base.  I have been having Eagles Pride work on my coach for routine maintenance and so far, it's been a good experience. 
Don White
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Eric Maclean

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Re: Aqua hot diesel and electric not working
« Reply #12 on: December 07, 2021, 02:04:01 AM »
Don
Karen and I will be in the Titusville area in a couple of weeks for the remainder of the winter.
Eric
1997 Patriot Yorktown
3126-B
2009 Chevy HHR
Roadmaster falcon tow bar
Demco Air Force one tow brake.