Most likely cause is an airlock in the cooling system
Personally I do not know about a G20 1990 Chevy Van but the basics of heating are, the thermostat, heater control valve, heater fan and heater matrix. Does the van overheat at all, engine wise? Could be possible the system just needs a flush out. When you turn the heating dial (presuming it is a dial) you should hear a clunk which normally indicates the heater control valve switching over. Other than that, I've said all I can. Hope to be of some help, hope you get it sorted out.
Yes, the Ford E-350 van typically has two heater cores. One is located in the front of the vehicle for the passenger compartment heating, and if the van is equipped with rear heating, an additional heater core may be installed in the rear area. This setup allows for more effective heating throughout the van, especially in larger models. Always consult the specific model's manual for precise details.
If your van has rear heating it will have hoses and a heater core back there, that is most likely the source of the leak.
if it has rear heat--it has hoses and a heater core for the rear heating system--could be any of this
Hi, If you have an extended van with heating and cooling in the back portion of the van, that is an auxiliary pump that is use to help circulate coolant to the back of the van. This is used by the heater, in the rear.
If your van is equipped with the rear climate control heating/cooling option, then YES, there are two heater cores.See "Related Questions" below for more
if the heater stoped working it sounds like a restriction or total blockage in the coolant lines, or its your water pump. take it to a shop as this can kill the motor through over heating.
probably because its old. take it to a garage, they'll tell ya ....check the heater control valve.and thermostat..................and the other answer is a waste of time.....................
can I buypass the rear heater valve and run two heater 1986 gmc van
It is possible that there is an issue with the blend door actuator or the heater control valve. These components control the temperature distribution between the front and rear heating systems. I recommend checking these components to see if they are functioning properly.
Sounds like your thermostat is done for. The water in the hoses is probably heating up from being close to the hot engine. This continued to happen to me after i replaced the thermostat twice thinking maybe i had bought a bad thermostat turns out it was the heater core. Both the front and back were pluged.
it is located inside the heater control box up in behind the centre of the dashboard,to remove and replace the dash has to be completely removed.