Our Hydrohot had been acting a little strange this year. Not firing smoking at times and then it would work perfectly fine. Really started acting up when we were at around 8,000 feet and I attributed it to high altitude. Opened intake and it worked fine for awhile but every once in awhile would not start. Blower runs but no burning. Got home set intake back to normal and it fired right up every time.
This weekend it started acting up again, would run fine then would not start. If it did fire lots smoke from the times it would not fire.
At this point I knew something just was not right. Started troubleshooting checking voltages. Verifying coil is firing, solenoid opening etc. Same as before sometimes it was right other times it was not. Then I finally got it at a point of not firing and checked voltages at coil. Nothing, solenoid not opening either. Tapped solenoid and it took off. That ended up being a coincidence, next time it was stuck in the start mode, tapped the Webasto controller and it took off running. Tried it again and sure enough the controller was the problem.
At this point I started looking at options to repair, brand new controller was over $800, I could send it off to have rebuilt for $350. Both expensive options so I said what the heck lets pop the cover and take a look. This was after finding a thread where someone else also opened theirs up.
This fix may not be for everyone but thought I would share with those that may want or need to tackle in the future.
Opening up is not to hard. The top plastic part is held by some retention bumps on the side. A wide flat piece of aluminum and a couple taps on each side popped it open.
This is after removing from the burner. It just slides out the back. Do not make the mistake I did and remove the bracket around the box. This is not required.
Once the top is off the Controller board slides out. This is an old school analog controller with many through hole devices, resistors, diodes couple transistors, capacitors and the control relays.
First was inspecting the solder joints I had read some of these were not quite up to snuff and may need touched up. They all looked good.
Second inspect the devices for blown , burnt or leaking capacitors. They all looked good.
Third inspect relay contacts. These were dirty and pitted some with this condition intermittent problems were a possibility. These were cleaned with a very fine crocus cloth. Then cleaned with contact cleaner.
Then put it back together and see if it works. Immediately noticed a difference, I could clearly hear the relays click, solenoid click and it started immediately without hesitation. I have done this several more times and all with same result. I will continue to test but think this may be good to a while longer. Next time I know what to do if it starts acting up. Cost $0.
Webasto Controller
End Cover removed
PCB layout with all the components. There are 4 SPST relays and one DPST relay. 6 sets of contacts that required cleaning.
Back side solder joints. I had read where others thought the board got hot and discoloration of the board. The coating on the back makes it look burnt but it is not. It is only the coating pooling in areas.
And this is one of the contacts on the relays.
Linear Mode
