Open the hood and the Coolant reservoir on the '92 Previa is next to oil reservoir on the left side.
Unscrew radiator cap from the coolant reservoir, add the 50/50 mix of coolant fluid into the reservoir. (Recommend use Prestone extended life coolant)
Fill the coolant into the reservoir, it take about 3 gallon, and be sure that the coolant is pass the full mark of the reservoir. Now, turn on the car, during the engine running (about 10 minutes) kept check the level of coolant be sure it still maintains pass the full mark level. Screw back the radiator cap to coolant reservoir.
Run engine for another 30 minute. This will ensure that thermostat is open and and ensure the fluid is circular all around of the radiator and hoses. Waite engine cool down, then open the radiator cap and check the coolant fluid level. If the level is low then add more coolant. Do not fill the coolant pass the full Mark's point. If the coolant fluid is still the same as in full mark then it is good.
Continue to check the coolant fluid for next couple day. Besure that it is at the full level mark.
you may have added the wrong type of antifreeze or you just need to flush the system
By using water
Power flushing?? Any kind of flushing of the cooling system will clean the heatercore. They both use the same source of antifreeze.
above heater controls center of dash
Toyota Owner's Manual and Automotive Repair Manual say Previa with 2TZ-FE (non-supercharged, which is the case of 1990 Previa) cooling system total capacity is 13 U.S. qt.
look in how to bleed air off cooling system
Where is the fuse for the cooling and heating air conditioning system on a Toyota prevla 1994?Read more: Where_is_the_fuse_for_the_cooling_and_heating_air_conditioning_system_on_a_Toyota_previa_1994
I recommend flushing the system and replacing Dex-cool every 5 years or 100K miles.
Deon
Usually if it's not serious, check the cooling system hoses.
A "professional flushing of antifreeze" is when a mechanic or other paid professional connects a hose assembly to your car radiator while at the same time opening the release valve (usually located at the bottom of the radiator) and forces water thru your car's water cooling system. The effect is to cleanse the system of old and rusted water and old antifreeze. This procedure is usually done just prior to adding new antifreeze to a car's cooling system, most often before the winter driving season. The end result being a more effective cooling system for the car. Hope this helps.
It means you are having a problem with the charging system. Have the alternator and battery checked. Good Luck!!!