Clicking sound under the hood

There is a clicking/ticking sound that seems to be coming from under the hood on the passenger side. Every now and then it is not noticeable but for the most part, it is always apparent. Also, seems to intensify with acceleration. Coolant and oil are both at appropriate levels. This may or may not be relevant, but the heater just barely blows warm air. By using the term barely, I am being generous.