I have recently purchased a 2004 2.5x forester with 55k miles. I turned the heater on for the first time tonite and while at idle with the engine at normal operation temp. a relay kicks on and cycles the fan for about 5 seconds. the idle also increases about 500rpm, then returns to normal when the cycle completes. this continues to repeat itself at idle... no engine light issues....any ideas whats up? thanks for all your help in advance