1992 Camry 2.2 already replaced thermostat and still getting warmer than it should...almost in the red...here is the kicker, it only does it after about 10 min of driving on the highway. After i get off the freeway and driving on the surface roads it does fine. It does it with or without the a/c on.

You don't say how many miles are on the car or if the radiator is original or not, but this could be the result of a partially clogged radiator. It can handle the heat of slow to moderate speed driving but can't take the extra heat created by high speed highway driving. That assumes you are not low on coolant due to a leak somewhere. What you can do is remove the radiator and take it to a radiator shop to have it flow tested. It may be clogged with lot's of scale and that is restricting flow. If you don't know how to remove the radiator, refer to the generation 3 sticky at the top of this forum. It's pretty easy to remove. You may have to put in a new one, if the flow test shows it's capacity is deminished.

Mike

You also need to bleed the cooling system after doing any replacements (including the thermostat).

Oh - wait - maybe not. That's true for an Accord, but a Camry might not need it.

it has 127000 miles, pretty sure it may be the original, I just bough tit about 2 1/2 months ago. Will try the flow test. Any other ideas?

No other ideas. You will definitely have to bleed the cooling system after installing any cooling system component that requires draining all or some of the coolant. I hope that was done previously. To bleed it properly, park the car with the front end lightly elevated. Set the heater control on to defrost. Remove the radiator cap and start the car. Let it run like that at least 45 minutes to an hour. Watch the bubbles come out the top of the radiator. Add more coolant as necessary and when you think you are done, (no more bubbles) close the system. Then take it for a ride. When you get back check the overflow; bring it to full by adding more coolant if necessary. Keep the mix at 50/50 coolant and water.

Mike

I have already done that with the coolant. I am probably going to try a new radiator when time permits. I will let you know how it turns out. Thanx all who replyed.

Just a thought, but have you tested the thermostat I had the same problem found out the thermostat was only opening halfway keeping it from overheating in normal driving but at highway speed it restricted it enough to push it up.

Haven't had this problem with my Camry yet but have with other vehicles. What I discovered is there are typically 2-4 "grades" of thermostat for a given vehicle. Naturally they get more expensive as you buy the better grade; doesn't seem like there would much difference at the time of purchase (other than the price which can be 3X or so from the cheap to the best)
however that price gets real cheap after you have made multiple replacements. As for me I'll buy the better one the first time and avoid the hassle.

Flush the entire cooling system with a cleaner. Refill it, bleed/burp it a few times. Change the pressure caps.
Finally, make sure the fans are working when they are suppose too. It's not uncommong to burn a fuse, or relay over time.