What to check: furnance or piping? Urgent

[BTU]

I set temp in my house as 21 degree. The main floor is around that temperature. The second floor is 2 degree lower.

The problem is, one bedroom's temperature is only 15 degree. Extrem cold. The air out from that heat outlet is total not warm.

Anybody know what's the problem here? Is that furnance problem or piping problem?

Appreciate in advance for your advice.

 

[fallleave]

DUCT

check your duct system

 

[BTU]

check your duct system

Thanks.

The duct system is hide under the wall, and my basement is finished. How to check it? Do I have to hire some specialist to check it?

 

[傻宝宝]

在距出风口1尺左右的地方一般会有一个类似阀门的东西，有可能是关闭的。伸手下去把它打开。