My heather does not work correctly

I drive a 2008 Toyota Tacaoma X-Runner, I have a problem with my heather, my AC works fine (I only have this problem when it's starts getting cold, because it works fine when it's not cold).

My nob to control the heather is old school, on the left it's blue for cold and on the right it's red for hot.

When I try turning my heater on 95% of the time it does not work as it should, if the heat is on the hottest temp (the nob is all the wait on the right hand side) I can hear the air forcing it's self to come out, and only feel a little bit of the air coming out (this is with the air force at max force), but than when I start moving the nob towards the left handside (toward the blue side) right about the middle of the red side (hot temp) I can hear when it start working like it should (the air comes out full force) and feel the actual air coming out (but it's is never actually warm, it's more cool, and it's at a medium temp, so it should be at least warm).

Yesterday for example, I jumped in my car and my heater worked pefrectly fine, drove for about 5 mins, and I can hear exactly when it started not working (it sounds like something is covering where the air needs to come out, and it's forcing it's self to come out, all my car is this way, no matter if I change it to hit my face, feet or window).

To be honest, I've had it checked couple times, and they can't find anything, BUT when they check this problem, it's not cold outside so it works fine. Now that live in Chicago and not the west coast, I need my heater to work!

I hope I explained my self well, my dad has tried saying that my AC button is on when I try to put the heater on, BUT it's not and I still have this problem. Before I go in and get it checked, I want to see if I can find a solution myself, and maybe not spend A LOT of money.

Let me know.

Thank you

 

Have you looked at the cabin air filter lately? A mouse built a dandy nest on top of mine from a California duster I had in the garage. Could be there's a mouse nest somewhere in the duct work?
Maybe could remove the cabin air filter and blow air through all the vents to see if anything pops out.
Just something to look at.

 

I'd say your blend door/servo is stuck or in a bad mood most of the time.