fairweather
Samba Member
Joined: August 26, 2007
Posts: 663
Location: Aspen, CO
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 Posted: Fri Sep 03, 2010 7:28 am Post subject: |
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The search really works though you might have to do some reading to find your answer:
| tencentlife wrote: |
Witless Joe was describing this earlier in this thread: the free-swinging "forced air flaps" (called that in Bentley) are supposed to be slammed shut when the fan on high speed builds backpressure before the heater core. You can hear them shut when you switch the fan on high, especially when the van is parked or moving slowly. When I had my airbox apart this year I deduced that the baffle plate is there to build more backpressure to cause the flaps to close. Either the engineers miscalculated, or perhaps they changed their sourcing on cores for one that was more open to airflow later, but one or the other I believe necessitated the addition of the baffle plate.
I have proof, by the way: I left the plate out of my airbox, and now when the fan is switched on high the flaps can't be heard shutting. Because I wouldn't know what effect this would have on heating before I reassembled my dash, I added a simple mechanism that allows me to close them manually.
One thing is clear, removing the baffle plate delivers both more and hotter air. The difference in my heat delivery is like night and day. |
This is from one of your other threads:
| tencentlife wrote: |
| I came to the conclusion that it was an afterthought add-on, because the heater core by itself did not present sufficient restriction to cause pressure to build behind it and force the free-swinging fresh air bypass flaps to swing closed at high fan speeds (that's the "THUNK" you hear inside the dash if you switch your fan on high all at once). It definitely can be omitted, and if your fan is healthy you will get increased volume of air at the defrost and heat vents by doing so. Whether those flaps swing closed or not makes no palpable difference in flow or temperature, I rigged mine with a manual closure for them in order to find out and can feel no change whether closed or open. |
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