spa pump mysterious turned on, wont turn off

In the middle of the night, the blower for my patio hot-tub turned ON. I walked outside in the freezing cold to turn it off (the switch for the blower is in an outdoor switch box -- along with the switches for the filter, water pump and spa light) but the switch was already in the OFF position. I tried switching it back and forth, but nothing changed. I finally turned off all power to the patio and went to sleep.
When I returned power to the patio this morning, the blower went back ON. I played with the outdoor switch again, to no avail.
Is this problem being caused by a faulty switch? Can a switch just fail (because of cold and rain), causing an electrical apparatus to turn ON? Can I repair this just by replacing the switch? What do you all think?

 

It is doubtfull you have a defective switch, some units have a automatic circuit in them to turn on and heat the water when the water goes below a minimum temperature, I would suggest you check the specs on your unit. It might be it was just in the process of heating the water to keep it from freezing. If it has this feature then you might want to turn it back on and let it run and see if it does shut off after it reaches its minimum temperature. If it doesn't then you may have a relay that is stuck in the on position.

 

The tub has absolutely no automation -- it is an old, in-ground model. The blower should not be ON unless manually switched ON.
So does that mean it is the switch? If so, do I just replace it?

 

Try replacing the switch although it is unlikely it could be, check for a broken wire on the switch maybe shorting out against the other side of the switch itself.

A thing to try before buying a new switch is to remove the wires to it and tape them off in this the tub should not run but if it does then it is not the switch it is something else

 

to find out if the switch is faulty, disconnect the power and remove the switch, put marrettes on both wire individually, turn the power back on if the spa does not run the the switch is bad. If you have and ohm meter you can test the switch, with the switch on you should get a zero reading, with the switch off you should get an infinity reading