Here in Michigan we are very cold in the winter and sometimes very hot in the summer. This can cause not only condensation but expansion and contraction. This eventually could cause some solder joints on the circuit boards to become bad. I will leave the PA in the car but I always bring my keyboard inside. It may be just fine going in and out of the cold and heat but I don't want to take any chances.

Scott, I too used to leave my Gulbransen Theatrum organ, Leslie 142, driven by a Fender Bassman amp in the trailer year round. I wish I still had that bassman. It was built like a tank. Between the jarring and moving around, and the changes in temperature, I was always fixing the Gulbransen (for 10 years I was a tech). I NEVER had to touch the bassman.

Tom