Room Losing Cold Air?

Question:Last summer, our spare room was a good 20 degrees colder from the rest of the house. The air from the vent was very fourceful and the room stayed constantly cold.

This summer is the exact opposite. The room is now 15-20 degrees warmer and it is like an unbearable sauna! The only thing changed is that a window was broken but has been replaced and caulked numerous times. There have been no other changes. The air flow from the spare room duct seems to be much less also. The rest of the house is comfortable and the A/C freon was checked recently.

Could something be obstructing the vent or airflow be kinked somewhere? I am thinking of pulling the vent cover off and having a look.. Any ideas?

Answers:
I would also check that the damper was open (the little lever that shuts down the airflow on duct work) These are in the basement (if you have one and this is the 1st floor).
I would do what you are said and take the vent off and check the vent as well use an inspection mirror and look along the supply vent.
Try leaving the door open and see if that helps to get the air flowing.
One last thing (I have seen this happen) make sure the windows are shut.