sound from the heater

When the friends run the heating system, like a cricket, it made a fragrant blow when it ran the heating system today. What could be the reason thanks ...

The brushes of the heating engine wear out over time. It can make this kind of sound when it gets old. If the problem is really from these brushes, I don't know if they can only change the brushes. I usually know that the entire engine has been replaced.

I have the same sound too much, especially in the cold, because I am used to broadway.

I have the same voice, but especially when I start shaking, I get annoyed when I get to the front chest one day

I have the same friends! & nbsp; & nbsp; & nbsp; especially when he gets to the 2nd level, the sound gets worse when my wife first heard it.

I have the same problem, but the level 2 is very small, but I am afraid that the car will break itself down on the 3rd and 4th levels.

I do not have such a sound, but digital air conditioning does not direct the up and down airflow. I wonder how we solve it

I wonder if nobody could solve this problem & nbsp;