Hydrohot overload fault

[Lawrence Tarnoff]

I need some counsel on next steps on curing this fault.  Here's what the service manual says:

4.13 Overload Fault Indicator Light
This indicator light will illuminate RED (reference Figure 5) whenever one of
the following conditions have occurred:
1. The Hydro-Hot is off due to an electrical overload (i.e. short) in the
main VDC power supply circuitry.
2. The Hydro-Hot is off due to a combination of high electrical VDC
power loads and a high surface temperature of the Electronic
Controller.
The Hydro-Hot will automatically restart once the electrical overload (i.e.
short) and/or high heat condition is corrected

I suspect I have a short somewhere.  What's the best way for a novice to identify the location and correct it?

Thanks, folks!!

[Steve Huber Co-Admin]

Lawrence,
First I'd check your DC  (battery) voltage. If it is greater than about 14.5-14.8v, the overload will trip due to high voltage.
If the voltage is OK, then verify when the problem occurs. If it occurs even when the Pre-Heat and Electric heat switches are off, these circuits are probably OK.
I'd next check for any chafed wires in the HH that could be supplying a path to ground. If everything looks OK, start eliminating circuits. Key electrical loads are the stir pump, circulation pumps, fans in the heat exchangers, and the controller itself. Check for a short at the pumps by either unhooking the red wire at the spade connection going to the pump or (preferred) disconnecting the red wire at the controller connector (usually J3). This latter approach will catch a short anywhere in the wire between the controller and the pump. You will need to remove the cover on the controller to access the connector. On mine the wires can be disconnected by use of a small screwdriver. Use the controller wiring diagram as a guide. Check 1 circuit at a time and reconnect it before checking the next circuit. You can use the same method to check the heat exchanger fan motors.
If you don't find the problem, I would suspect the controller itself.
Steve

[Lawrence Tarnoff]

Thanks, Steve.  This is going to be an interesting journey!

[Lawrence Tarnoff]

Resolution: Uncertain of my skills at fixing this, I found a nearby -- OK, 90 miles away -- authorized service center and took the coach there this morning.  Tech found that the blower bearings were frozen.  New bearings -- $126 for a pair of bearings!! -- did the trick.  While there, I had him do a full maintenance.

Larry

[Steve Huber Co-Admin]

Glad you got it fixed. Frozen fan bearings would sure put a load on the elec. supply. There's very few items in a HH that cost less than $100. 
Steve

[Lawrence Tarnoff]

Thanks, Steve.  The bearings look just like those I can purchase locally for a buck or two each.

Larry

[Gerald Farris]

Larry,
The $126 bearing price is correct if it is from Aqua Hot. It includes both bearings plus the nut, spacer washers, and spring washers that are used for installation. It also includes the ridiculous markup from Aqua Hot. 

When I replaced the blower bearings in my Aqua Hot, I just purchased the bearings and nut from Aqua Hot for $52 because I did not have it disassembled before ordering the parts. However, after disassembling the unit and inspecting the bearings, I was able to locate industrial grade bearing made in Japan for about $6 each. You do not want to use the $1 bearings in this application. So if the bearings fail again, the bearings will cost me $20 less for each of them.

I also located the Danfoss 030F6103 nozzle that is used in my Aqua Hot for $6.95 each on EBay. So I purchased 3 of them for less than $25 with shipping. If you spend a little time in research, you can cut most of your Aqua Hot parts cost at least in half, and with the maintenance requirements on these units, that adds up pretty quick.   

Gerald   

[Lawrence Tarnoff]

Thanks, Gerald.  Hopefully, this repair will last a while.  The shop that did the work said Aqua Hot does not give them any break on parts price.