07 Mazda6 Temperature gauge fuctuates, heat barely works.

Hi guys,

I recently topped the coolant off in my 6 and a week later noticed my vents would blow cold air when the car was warmed up. The heat does work, but inconstantly and seems to revert back to cold air after a while. More troubling, my temp. gauge has been fluctuating from slightly below 1/2 to right under the red line...before it would never go past halfway.
When the car is running, I will occasionally hear the radiator fan running quite loud. All of this just as winter hits...

Anyone know what's wrong?

Thanks for looking.

EDIT:

Well, I found the source of the problem. There is a hose near my battery that is leaking coolant.

Upon further inspection the smaller part of the T that goes to the TB was broken:



This si the bugger, for those who haven't see in in all it's glory.


I put in a 3/4 90 elbow and blocked off the smaller diameter tube with a screw...is this the correct way to do the TB bypass?



Unfortunately I'm still loosing coolant like crazy. I filled up before leaving for work, and an hour later my coolant was 95% gone.