Storm season and appliance control boards

Roughly 68 thunderstorm days a year pass over this part of Florida. That is the figure worth planning around, and it explains a service pattern we see every summer: an appliance whose mechanical parts are all perfect and whose electronics are dead.

The surge does not come in through the appliance

This is the part that is usually misunderstood. A nearby strike or a utility switching event puts a transient on the premises wiring. It arrives at the appliance through the same cord and terminal block that supplies it, and it takes the path of least resistance to the most sensitive thing in the box. Motors, heating elements and compressors are electrically robust — they are coils of wire and resistance wire, and a microsecond transient barely notices them. The low-voltage side of a control board is the opposite: small traces, small components, and a power supply designed for a stable 120 or 240 volts.

So the aftermath is lopsided by design. Everything that costs a lot to replace tests fine, and the thing that fails is the board.

Telling surge damage from ordinary failure

Evidence	Points to
Two or more appliances misbehaving from the same night	Surge
Board dead, all loads test good	Surge or supply
Scorching or a blown trace visible on the low-voltage side	Surge
Gradual onset over weeks, one function at a time	Ordinary component ageing
Fault that follows heat — appears hot, clears cold	Thermal, not surge
Only one appliance, no storm in the timeline	Ordinary failure

The multi-appliance clue is the strongest one available. When we are called to two machines at the same address and both stopped on the same evening, we stop diagnosing them separately and start looking at the supply.

Check the supply before the board

A dead display is not automatically a dead board. Before we quote electronics we confirm both legs of the supply at the terminal block, check the breaker under load rather than by eye, and look for a loose neutral — which produces the most confusing symptom set in the trade, because it makes voltage swing with whatever else in the house is running. Replacing a board into a bad supply destroys the new board, sometimes within days.

The half-failure

Surges do not always kill outright. A partially damaged board is the frustrating version: a refrigerator that cools normally but has lost its ice maker and its dispenser, an oven that bakes but will not broil, a dishwasher that runs one cycle and not another. The temptation is to chase the missing function through its own circuit. When the timeline points at a storm and multiple unrelated functions on one board have gone at once, the board is the common cause and testing each output at the connector proves it quickly.

What actually helps

Whole-house surge protection at the panel is the meaningful measure, and it is electrical work rather than appliance work — we do not sell it and we do not install it. Point-of-use protection behind a built-in appliance is better than nothing but is rarely accessible once the unit is in its opening.

The cheap habit that helps most: if a storm has been directly overhead and an appliance behaves oddly afterwards, power it down at the breaker for a full minute before concluding anything. A fair number of post-storm calls are control boards that have latched into a fault state and will clear on a genuine power cycle. It costs nothing to try, and if it works you have saved the visit.

Parts availability

Control boards are the parts most often on extended lead times, and they are also the parts most often needed in a hurry in August. We give a realistic date on the estimate rather than an optimistic one, and if a board is unavailable we say that plainly instead of leaving the appliance apart while we wait.