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poolguy810, owner - pool and spa service company
Category: Pool and Spa
Satisfied Customers: 1675
Experience:  Servicing pools and all brands of spas for over 28 years.
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I have a RUUD pool and spa heater, model 266A. I can turn

Customer Question

I have a RUUD pool and spa heater, model 266A. I can turn the unit on, with the display showing "off" and the temperature, but the mode switch will not allow me to select pool or spa or temperature.
Submitted: 2 years ago.
Category: Pool and Spa
Expert:  Phil replied 2 years ago.
It is most likely that the electronics control module has failed. Those are the classic symptoms of that.
Lets do a heat stress test on it and see what happens.
Stress test the printed circuit card.
Use a hair drier to slowly and gently warm the card to 120F (warm to the touch but not hot and not over 140F)... if you get any change in behavior that means the card is bad...
A micro crack has opened in the printed circuit at a solder joint, or inside its CPU in that case .... or a short circuit has developed as the card expanded when you heated it.
Constant expansion and contraction as these electronics heat and during their duty cycles over the years is what wears these cards out.
It is also a good idea to replug all of the connections in the unit, that burnishes any oxidized terminal connections and will sometimes solve the problem, especially at the printed circuit card and in any sensor molex connectors. Do that with the power off to the unit of course.
These cards are also damaged by Electrical Spikes caused by power failures and lightning. These high voltage spikes can literally explode the fine 'wire' connections inside the chip. There is also a shunt type device, often printed on to the card that allows a high voltage spike to arc across to ground harmlessly, some of these can wear out after a few times and allow the high voltage spike into the rest of the card and the CPU micro-circuits. The high end printed circuit cards use a large capacitor like device, or several in parallel, to capture and release such surges, these do not wear out.
We can go from there.
Customer: replied 2 years ago.
pretty generic response and not worth $5. I can see I need a repair person to look at the unit.
Expert:  Phil replied 2 years ago.
Hello again, trouble shooting is a step by step process... so far I have just posted an 'information request'.
There might be many of these before I arrive at a diagnosis... I am not paid unless and until I provide a diagnosis that you are happy with..... and choose to rate positively... and that is entirely up to you, even if we end with a solution and a fix. You have the option of me not getting paid.
That is the worlds best deal, often saving our customers the cost of $200 or $300 service call.
Let me know if you want to continue on that basis or not. If not I can opt out to another of our experts here.
Good luck with it any way you want to go.
Customer: replied 2 years ago.
I don't think this process will be helpful. Thanks for trying.