SONY KF 50SX100 Projector TV problem

Hello every body,
I have a SONY KF 50SX100 Projector tv problem. when i open the tv i can see the images for almost 2 minutes. And then the images and sound cutting and the tv seems like going to stand-by mode. Almost less then 1 minute later images and sound coming back. Around 2 minutes later its cutting view and sound again.
This event always repeating. I opened the back cover. When does make this problem fan always working. Somebody have any idea about this problem?