Hello, Check the 2 heater hoses on your Firewall. When you engine has run and is warm, both water lines should be the same Temperature IF the heater is turned on.
If the water hoses are hot, then you have a problem with the Ductwork under the dash. One of your ductwork doors is not opening to let the air go through the heater core.
But if the heater hoses are not the same Temperature, you are not getting water flow through the heater core. You need to find the water valve for the heater in this instance. It can be operated by a cable from the dash or by Vacuum.
The cable can slip its mounts and when you set the heat, only the lever is moving; nothing under the dash is moving the water valve. You would either mark the position of the water valve or have a helper observe if the part moves when the dash lever position is changed.
The Vacuum type can be checked by disconnecting the vacuum line and then starting the van and see if there is a vacuum leak on this removed line end. If you are not getting Vacuum to this control when the dash lever is set for heat, the plastic valve associated with this is bad. If you have a remote Vacuum source like a Vacuum pump, you can try to pump Vacuum to the Heater valve which should open it. The Vacuum pressure should maintain itself unless the water valve leaks the Vacuum pressure out of the valve.
A clogged core is a possibility and without removing it you would disconnect the water valve and the remaining heater hose and attempt to force water from a garden hose through the heater core. You can attempt to backflush the core by forcing water into the water line that runs to the front of the engine. The water line from the top of the engine usually pushes the flow from top to bottom.
You do not need to run the engine, you would have a mess and lose all the coolant for this last procedure. Just catch the Antifreeze leaving the heater hoses initially and backflush the heater core. Hopefully you will not need to backflush the core or complete this last procedure.
Answers & Comments
Hello, Check the 2 heater hoses on your Firewall. When you engine has run and is warm, both water lines should be the same Temperature IF the heater is turned on.
If the water hoses are hot, then you have a problem with the Ductwork under the dash. One of your ductwork doors is not opening to let the air go through the heater core.
But if the heater hoses are not the same Temperature, you are not getting water flow through the heater core. You need to find the water valve for the heater in this instance. It can be operated by a cable from the dash or by Vacuum.
The cable can slip its mounts and when you set the heat, only the lever is moving; nothing under the dash is moving the water valve. You would either mark the position of the water valve or have a helper observe if the part moves when the dash lever position is changed.
The Vacuum type can be checked by disconnecting the vacuum line and then starting the van and see if there is a vacuum leak on this removed line end. If you are not getting Vacuum to this control when the dash lever is set for heat, the plastic valve associated with this is bad. If you have a remote Vacuum source like a Vacuum pump, you can try to pump Vacuum to the Heater valve which should open it. The Vacuum pressure should maintain itself unless the water valve leaks the Vacuum pressure out of the valve.
A clogged core is a possibility and without removing it you would disconnect the water valve and the remaining heater hose and attempt to force water from a garden hose through the heater core. You can attempt to backflush the core by forcing water into the water line that runs to the front of the engine. The water line from the top of the engine usually pushes the flow from top to bottom.
You do not need to run the engine, you would have a mess and lose all the coolant for this last procedure. Just catch the Antifreeze leaving the heater hoses initially and backflush the heater core. Hopefully you will not need to backflush the core or complete this last procedure.
Check the heather core to see if it is pluged