How to check cut-off valve for cabin heater radiater

You have air in the radiator system. If cool air was coming from the heater in the car, then the radiator fluid was not circulating through the heater and also the engine.

water from the engine cooling system enters a small radiator that sits behind the dashboard through the firewall look in the engine bay for 2 water pipes going into the cabin one of them should have a valve on it check if its working when u select warm at the controls sometimes the valve is behind the dash before the heater radiator

check coolant level and color if milk chocolate head gaskets blown.or bad thermostat stuck shut
any white stinky smoke coming from tail pipe?

don't know this van specifically, but some things to check, make sure cabin filter is replaced or clean, you didn't say if the blower itself works, if not, correct or replace. Check the hoses going to the heater core, if hot water is flowing thru the core, both hoses should be hot. Check the heater controls to make sure doors in the system are opening closing as they should, you may just be drawing in cold air and not going thru the heater core.

Hi James, If we're talking about the radiator for cooling the engine, check the thermostat and water pump. If we're talking about the cabin climate control, check the valve operation of the cabin temperature control. Regards John

It sounds like a heater cord problem .The heater cord is basiclly a small radiator on the inside of the cabin .On older vehicles sediment tends to fill it up so less coolant can flow through it their for less heat can transfer from the engine witch is the source of the heat into the cabin .Some vehicles also have a gate valve or ball valve that turns and shuts off the coolant flow the from the water pump witch drives the coolant every ware it needs to be in the entire system your control inside the cabin opens and closes this valve to let coolant into the heater core if you even have this valve .The best way to tell if the heater core is flowing is to warn the vehicle up to operating temp look for the 5/8 heater hoses going to the left side of the fire wall there will be 2 of them 1 is in 1 is out .One side should be much cooler with the heat on full if not its the core or the valve if you have one .

1-your thermostate is stuck open half way. thermostate is a simple device that made of enlarging metals when heat is applied. it suposed to be in close position to allow engine heat up, when specified temp reached it opens and let it flow and radiator tries to keep coolant cool.when it is broken it stucks or it acts slow or it wont acts at all. in your situation it is stuck open half way. it allows enough water to be heated but flow is limited to heat cabin heater.

2-if there are cabin heater selenoid/selenoids for two different temperature for cabin left and right, on some instance those selenoid valves to adjust cabin heater stuck open or closed like thermostate acts on first case. so heat is not enough to heat up cabin heater.

On most cars (all that I know of) the heater works by directing the hot water from the engine through a small radiator in the cabin and blowing air across it with a fan. If you hear and feel the fan blowing air then it could be that the valve that diverts the hot water to the small radiator is bad and no hot water is being circulated thus no warm air. In order to fix that you would have to locate the valve and replace it- many times they are in hard to reach places.
hope this helps

uh oh... you better hope its not in your heater core!! hoping its in thermostat.
I hate dash removal :(

Check the valve that controls coolant flow to the cabin