Pulsating-like sound coming from engine at high speeds
 

I have a weird problem, and can't seem to identify it.

It's a deep pulsating sound that comes on periodically from the engine bay at high speeds, I also think it is linked to the heater. Trying to remember, I have always had the heater on, when these surging/pulsating noise came on at higher speeds.

Any ideas to what my problem could be?


There are no changes the car's operation, just the sound is very noticeable.

air lock? Heater core? water pump?

depending on the age of the car, it could be the blower motor?

I haven't solved the problem yet, but it can also be possibly that the a/c needs to be recharged.

But the blower motor, I will definitely check that out as well.