My 1990 Volvo 240 overheats when the ac is on whats wrong?

Answer 1

Engine overheats When a car or truck overheats idling, in town, on the highway, while towing, etc. it is important to find out the reason to prevent engine damage. First, with the engine cold, make sure the radiator is full of coolant; if it is low, fill it and keep the radiator cap off while the engine idles to insure all air is bled out of the system. Check the coolant level daily; if the coolant goes down without visible leaks, it may be a head gasket starting to leak which will also cause the heater to blow cold air due to the lack of available coolant. If the coolant stays full, but the car continues to overheat, the next step is to replace the thermostat in the engine and flush the cooling system if that has not been done over the last few years.Buy a thermostat at a parts store and a PRESTONE flush kit which has excellent directions on the package.After completing these steps and the vehicle still overheats, have your cooling fan sensor/switch ( if equipped)checked out to insure it is coming on. Water pumps are seldom the cause as they are mechanical and will continue to work until their bearings give out. Finally, the radiator itself is often the problem as it tends to build up corrosion internally which prevents it from transfering engine heat to the coolant. Remove it and have it 're-cored'. One of these steps will solve the problem.