Toyota Repair: Paseo Thermostat, 10mm nuts, 1992 toyota paseo

Question
My girlfriend has a 1992 Toyota Paseo and it has been starting to overheat. She says that it gets worse when the air conditioning is on, which by the way doesn't blow cold air. The temperature has not been up to the red but it has been close.  Our only idea is that it could be the thermostat, so where is it located and how do we replace it?

Answer
The thermostat is located just under the distributor, follow the radiator hose, its inside the round housing attached with two 10mm nuts.
If it still overheats suspect a problem with the radiator, when the engine overheats the A/C is designed to turn off automatically.