The fan in my 99 Buick Century Custom will not start. When i turn the knob to change between the fans i can hear the fans changing with clicks and hisses, but when i turn the control knob it will not start the fans. I think its a short or something because it was fine till i drove through some huge puddles in my alley and even then the control would work every couple of days when i would instinctively turn the knob on forgetting its broken. Now it wont turn on completely and i need the fan to defrost my windshield in the winter. Quick side note the A/C has not worked in a couple of years. I am fairly competent at home car repair but if you could make an explanation as simple as possible id really appreciate it. Thank you in advance for any advice or suggestions.