2006 crv weird engine/heater noise

i have a 06 crv with 150k miles. When the crv is running with the heater fan on, there is this weird noise coming from the front of the engine. The second i shut the heater fan to off...the noise quits. Its a grinding/nocking that gets faster when i rev the engine. It completely goes away when i shut the heater fan to the off position. Turn the heater fan to on, the noise comes back. There is no way this could be the heater fan because the noise is coming from the front of the engine. All fluids are up.

I'm not sure if you are in the defrost position when you turn the heater fan on, but the air conditioning compressor may be kicking in. I would unplug the air conditioning compressor and see if the noise goes away. A little late but I thought I would reply.

thanks mechhound....i was thinkng the same thing and am going to try this. I was waiting for a couple replies first so no you are not too late. thanks

yes...in fact the air compressor is cutting in. Why is it doing this. What is the fix?

It's normal for the AC compressor to kick in while you have it in defrost position. I'm not sure about the other heater positions. I guess the cure would be to repair the AC compressor if it is overly noisy. If the AC compressor is abnormally noisy you will probably want to repair it or unplug it anyway so you don't cause further damage to anything.