Hey Folks, Just got back from a campout today with our '98 Santa Fe and it was cold and rainy most of the weekend. Consequently, the heater was on overnight and it wasn't exactly quiet. When it would cycle on, the heater would make a whistling sort of sound which would last several minutes into the cycle before calming down. After the cycle ended the heater would turn on again a while later when Tstat called for heat and it would again get noisy. Any thoughts what this could be? I appreciate any help that you can provide. Thanks!