Need to bleed air our of cooling system on 1992 Lexus SC400

pressure in motor will help push out air to bleeders

to remove air from a cooling system , turn on the heater and loosen of the highest hose connection on the motor /firewall to let air out
best do it cold and a running motor helps circulate the air out

1. This method works best if the nose of the car is raised as high as possible. Park your car in your driveway. Let your car cool down. When your car is cooled down, you are ready to work on the cooling system.
2. Open the hood of your car. Secure the hood with the safety handle. If you have a newer car, you should have a bleeder valve on the front of your radiator. Check in your owner's manual for the location of this valve. If you do start your car, open the valve with wrench and let your car heat up. The excess air will bleed out of your cooling system. Keep your car on long enough to give the (trapped air) time to bleed out of your system.
3. Let your car cool down. Once the car is cool, take off the radiator cap. Did the level of the radiator fluid go down? If it did, it means you bled the air out of your cooling system. Replace the radiator fluid, turn on the car, and let it run. Replace radiator fluid as needed.
4. Step 3 (above) is the way you will remove air from your cooling system if you do not have a bleeder valve on your radiator. You will leave the cap off the radiator. You will run your car until it heats up. As the air dissipates, the radiator fluid level will go down. You will fill up your radiator fluid to the correct level. Be careful because the heated radiator fluid will be hot. Always wear leather gloves and safety goggles when working on your radiator.
5. Once the air dissipates and you fill the fluid, shut off the car. Let the car cool down. Once the car is cool, put the radiator cap back on the radiator. You may have to put more radiator fluid in the radiator. The level may fall as the car cools down. Now it is safe to drive your car. You have removed the trapped air from your cooling system.
   

Heater cold when at idle: Try stopping on a steep incline--does the heater stay warm? If yes, what you have is an air bubble that hangs at the heater hose until pressure from the water pump blows thru it as the engine speeds up. Park on an incline, open the radiator cap, run the engine until the thermostat is open, and fill the radiator to the neck. Wait until the level stops dropping and make sure bubbles don't continue to come up. If they do, you may have a blown head gasket that will keep forming these bubbles until you change the gasket. Please let me know if you have questions.

No bleed valve. If you want to get the air out of the system, just run the car until it's hot and the thermostat opens, and then run it some more so that the coolant is fully distributed. The air will get to the top of the engine - the filler cap. Then after it's cool you can refill the engine, and the overfill tank.

the computer is bad and also these cars are known for the insturment clusters to go bad along with the computer. get them both fixed and it will solve your problem.

preform a pressurized collant flush , take it to a raidior shop to have it done , they will clean and blow out all blockages that might cause your car to over heat. also check to make sure you dont have air pockets in your anit freeze, if you do you need to bleed the system out after you have it flushed , your car should have a blead valve to let out the axcess air ,if not drive it down the road with the cooaint overflow cap off , not the radiator but you need to flush out the system first , add new anti freeze then bleed out all air pockets, hope this helps

remove the 2 10mm bolts on top that you can see, then remove front part of inner fender liner you will find 2 10mm nuts. you will need a long extension. Recomend using duct tape around feneder area to avoid scratching.

Change the 15amp fuse in the kicker fuse panel labeled cig. My stopped working for the same reason.

Mine did that and it was low on freon recharged it now works great