So I know its the wrong time of year to hunt this down, but figured I should start looking before I need it...

I dont drive the van at all in the winter, trying to keep it out of the salt here in NY. But occasionally it needs to make a run to go get some stuff, and I noticed that the heat output is really not adequate. It gets warm-ish, but definitely not hot, and you need to dress seasonally or you would be cold on a road trip. Its set up as a 15 passenger van with a rear heater and AC.

I did have the coolant changed out last summer after we picked it up, so I thought something could be air bound, but I would assume that should have cleared itself out by now after several drive cycles and turning the heat on and off.

The gauge on the dash goes up with engine temperature, and I can see it fall when the thermostat opens up, so I presume that is working fine.

Are there any other places that I should start looking? Is a plugged heater core the first place to look? Is there a vacuum line that I should be trying to find? I do have airflow out of the vents, its just not warm when the outdoor temperatures are low.

 

Check the heater hoses going into the heater to see if they are both equally hot. If they are then it could be a bad blend door actuator.

 

Ill give this a shot next time I have it out and warmed up. If they aren't both warm is the control valve a common culprit?

 

I newly learned about:

Checking that the vacuum hose from the black approx. 5 inch round plastic ball under the battery goes to the T-fitting about 18 inches from there -- where one of the junction's hoses goes up to the blend doors and the other to the intake manifold - on the intake manifold side passenger side i think i recall.

Mine was completely disconnected from the VACUUM RESERVOIR/"vacuum tank" ("black ball" i called it above) AND, for me, everything OTHER than the thinner hard plastic hose that goes from the T-junction (noted above) to UP to the blend doors were in fairly rotted shape. The thin hard plastic hose gets hidden after about 8 inches i think as it goes up to under/behind the dash etc.

Pretty sure that little T-junction plastic bit has a one way valve in it as well. Can order from RockAuto etc.

Just a quick write - my best at the moment.


NOTE; i have a 2010 4.8L

 

Thanks for that tip.

Ill need to get in there and check the heater hoses to see that they are hot, and then see if the vacuum lines are all connected to the right spots. Appreciate the response!

 

Some info here:
climate-control-vacuum-tubing-issue-117027

some vans also have a vacuum operated valve on the heater hose.

 

NICE link - Super helpful !!!