Okay so im not the best person when it comes to working on cars mechanically...I have a 1999 Cavalier -2.2l- Runs really strong does have any problems in that field.

The car runs hotter than normal and sometimes will start to climb after 25-30 min over running on the road. if it sits at idle it seems to do fine....

I replaced the Thermostat this past saturday with a Fail Safe.

Radiator was replaced 2 years ago

NO Signs of Leakage as far as i can see

its holding water

now the heater hose that runs to the top of the radiator is full of hot air even when car is over its limit for the thermostat to open.

 

Did you change coolant?
Do you have a cap on the radiator?
Pictures would help!