This could be due to a number of reasons.
Furnace blower wheel rattling.
The noise is made when it hits against the blower house casing.
If you follow these steps and catch it early you should only face.
The blower wheel has become loose and is now hitting the side of its housing.
Scraping and rattling metal.
If the blower motor isn t secured properly it can result in a rattling noise when your furnace is turned on.
Sometimes the mounts that hold the blower in place can become loose which can cause your blower to become misaligned.
It is so loud.
The most common issue is the blower wheel coming loose.
If you hear this sound it needs addressing straight away.
Furnace making a rattling noise.
The rattling could also be coming from loose panels that need to be tightened.
If you are hearing metal against metal there s probably something wrong with your blower wheel.
You need to turn off your furnace immediately and wait for a professional to do a full inspection.
I have the temp at 70 degrees.
I think the niose if coming from where the spiny wheel is dont know what it is called but if i put my head of to the furnace i can hear it very clear.
If this is your issue you ll need a technician to come to check out your system and tighten any loose parts.
In order for blower motors to work efficiently and properly they must always remain in balance.