furnace not working correctly

[yingshan]

I have a 11 year old furnace. We've noticed an issue with the furnace over the past couple of days. When it runs it either just blows cold air or it won't warm up the house. If we turn the heat up to say 21 degrees it never warms up to that. It just remains 19 degree during days and drops during night. Anyone has idea what the problem can be? Is it a big problem worth changing a new one or a small problem just find someone to fix it. Urgent!!! please!!!

 

[ccc]

去《我爱我家》看看，那里有几个帖。

可能性：
积水
过滤器脏了

 

[sktime]

may be the problem is caused of your thermostat.

 

[贝宝宝]

跟我家furnace上周出现的问题一样
http://bbs.comefromchina.com/forum43/thread998438.html