Aquahot Controller

November 10, 2024, 05:20:27 pm

Hello all. Back again with another, old and persistent, problem. Hoping someone can shed light on this. I have a 1996 U320 with an Aquahot 431-12 unit. When i first bought my coach it worked fine. Flawless all winter. In the spring i had a certified technician service the unit. When she finished it worked fine. For a short time. I don't really think she did something to break it, but ever since I have never had it working right. The issue is:

DIESEL 12VDC BURNER SIDE (Not 120VAC Electric):
1) Turn on the switch in the kitchen to start the unit.
2) The motor turns on and does the start cycle for 10 seconds or so.
3) The burner ignites fine, every single time.
4) It runs for 10 seconds, then the light goes out on the kitchen button panel and the burn stops.
5) Does the cool down fan cycle and shuts off

I have gone through a lot:

1) Did the annual cleaning
2) replaced the fuel nozzle
3) replaced the flame sensor
4) replaced the photo disc
5) adjusted the electrodes
6) checked both AC thermostats and both are fine. i think i may have even replaced one. don't recall.
7) bypassed both thermostats, one at a time, to see if that was the problem. was not
8_) checked the fuel send and return by disconnecting both and connecting to a standalone tank of diesel and running return to an empty canister. Same behavior as described above. no difference.
9) have had the control board inspected and repaired by Jim Frerichs. Twice. and various electrical checks per his instructions.

I have not checked the fuel pressure with a gauge
I have not checked anything else on the fuel system, as it seems to be sending and returning as it should, and it ignites fine every time.
I have not changed any other parts that i recall.

You may notice i had Jim Frerichs service my controller twice. The first time i sent to him he said there were a few bad components. which was odd, as it worked completely fine until i had the unit serviced. to me this suggested that the service somehow caused something to fail in the board. Jim fixed the board and returned it. it worked flawlessly right away on the first try, once. after that it woudn't work again. then i sent it back to him and he found another fault. he fixed this, returned it, and same behavior. i then proceeded to do various electrical checks with Jim's help, and found nothing wrong.

it seems to me that the issue must be the controller. I don't know why, but that's what i think. Does anyone know if there is another place that inspects, repairs, or replaces controllers for these old units? I know Jim is on this forum. Jim, if you read this and want to take another look i would be happy to send both boards that i have. i will likely call you again tomorrow, anyway.

if anyone can suggest anything it would be most helpful. the control boards are Webasto SG 1553/12V 287.962,

If anyone knows of replacements for this that are direct old stock, or new plug and play, please let me know. I know they are expensive. i just want it working.

thanks to everyone in advance.

Re: Aquahot Controller

Reply #1 – November 10, 2024, 05:45:28 pm

MM, Call me, Rudy Legett 7 one 3 8 one 8. 3234

This forum will tell you I am a Factory Authorized Service Center. Call 8 to 8 central, any day

Re: Aquahot Controller

Reply #2 – November 10, 2024, 08:35:05 pm

Call Rudy in the Morning. Also make sure you save his number. He is great to call when ever your AH is out.

Re: Aquahot Controller

Reply #3 – November 11, 2024, 08:01:06 am

He did call. We had a good conversation and gave him some things to check on based on his symptoms. He is going to be a good Foretravel owner and hope he posts his adventures here some more. All the best.

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