I have a 2.2l 97 camry with 90,000 miles on it. Recently I have not been getting any heat at idle rpm's. I am just getting luke warm air from the vents. When I rev it up over 2000 rpms the heat gets nice and hot but drops back down within seconds when I take my foot off the gas. I don't know if I am just noticing it because its cold but it has been really cold outside (0 ot -25) sence this problem has appeared. The coolant levels seem good and both radiator hozes get hot once the engine warms up.Thanks for any help you can give.

Check the coolant level in the radiator (cold) and fill if necessary.
After check the overflow container for it's proper coolant level.
It sounds like your running low on coolant.

The radiator is full and overflow is right at the full line.

If the coolant level is normal, I would then change the thermostat. The thermostat may be stuck in the open position or it may be opening too soon. What is the position of the temperature gage on the dash? It should be at about the halfway position. Lower than that is an indication that the thermostat is not doing it's job.

Mike

Low fluid, air in system, faulty thermostat, or in need of a good flush. Good luck

Another possibility could be a partially blocked heater core or the temperature adjustment valve is stuck/blocked (presuming this gen still has one). Temps on the heater core hoses should rise independent of the larger cooling hoses since coolant flows through them in a separate circuit regardless of the thermostat position as the engine heats up. If they rise slowly, unevenly between send/return lines, or don't heat up fully until the thermostat opens, then there is a blockage or constraint. An infrared thermometer is a handy tool to use to test hose temps, heater core, and thermostat housing while keeping hands safe.

I wouldn't expect this gen to have a vacuum-operated blender door, but if by chance it does, there could be a vacuum leak in the diaphragm. More likely it is a servo motor....

Hope this helps!