Would have been built for R12, can be converted to R134a.
Sounds like "heater core" is shot-any coolant leaks inside the car coming from under the dash?,Have check, replaced.Or could just be an air lock in coolant system, which is better easy fix.
how to replace a heater matrix in a toyota previa
Try and get someone to read the ECU codes, that will tell you if the problem is from the "Knock Sensor". If it is you will need to buy a new one and replace it. They are very expensive and can only be got from a Toyota Dealer. To fit your self Drill a hole under the front seat(Directly above the ...
The oil pump may be changed when the oil level light begins to glow. Buy the oil pump from the eBay motors and it will be replaced.
The location for the idle switch of a 1992 Toyota Previa mini van can be found in the Toyota Previa Auto Repair Manual 1991 thru 1995. This can be purchased from the Toyota dealership.