Demystifying Vanagon heater & fresh air controls

Capt. Mike

The following is a transfer & consolidation from archives.

7/22/99 (2:18 PM)

I'm in need of a tip.

This used '88 didn't come with an owner's manual. Need to know how to control the fresh air intake. Will someone kindly explain the controls for the vent/heater?

Probably been covered in a prior post somewhere, but after 20+ hours of searching, no luck.


And thanks.

-- Chris

Robert Gavan (

7/22/99 (9:52 PM)

Top lever - right defrost, second lever - right heat, third lever - left footwells, fourth lever - left roof outlets in rear compartment, right and left front air inlets - levers down

Hope this helps.

Capt. Mike

7/27/99 (11:39 PM)

I posted this a while ago, but don't remember where. Bob's right, but it's a little more complex than that.

Simplest lever first, the 2nd controls the amount of heat. But the hot air to the windshield is mixed with some fresh so it's never as hot as cabin air.

The amount of fresh air that comes in is fixed and always "on." The top lever determines what percentage goes up to the windshield or down to the cabin. Of the amount that goes to the cabin, the 3rd lever determines how much of that goes to the foot wells. The amount that goes out the dash vents is controlled by their individual grill levers. So if you shut them off, you get more to the feet -- remember, fixed amount, subject to vehicle speed, coming in.

Finally, of the lower cabin air, the 4th lever siphons some off to the vents over the sliding door. This rear cabin air is never heated.

The A/C vents do not control any fresh or heated air. Conversly, no A/C comes out of any heat & ventilation system ducts.

Engine and vehicle speed affect air temperature and flow. So what is a good setting at highway speeds goes to pot in town.

To shut off all outside air, for example with A/C on: top 2 levers left, bottom 2 right, dash vents closed.

For maximum defrost, all levers right, dash vents closed.

Best cabin heat compromise and start point for personal adjustment, top lever 1/4 from left, 2nd & 3rd l/4 from right, bottom full right.

Capt. Mike

Something often forgotten in trying to get that elusive perfect level of heat is fan speed vs. temperature. We like to think that cranking everything to max with maximum fan is going to be the most heat, but often it's self-defeating. Since the heat inside the cabin is a matter of getting that incoming air warm as it passes over the heater core. If it's moving too fast, it can't pick up enough heat and you not only have colder air, it feels even colder from the same skin cooling effect as standing in front of a fan makes you feel cool.

So pick a lower fan speed that gives you the the hottest air if you want heat, and a higher one if you want ventilation and air movement. In the water-cooled Vanagon, usually 1st or 2nd is your best choice. Especially defrost where cold air is mixed in -- too much fan speed there never gets warm.

The same is true of A/C but has to be tempered with preventing freeze-up. If the cold air isn't removed from the evaporator quickly enough, it will ice up. There, pick a thermostat setting that matches the fan speed. Max cool + max fan, or lower cool + slower fan. Max cool and slow fan can cause that ice-up.

Capt. Mike

Sometimes, through bad engineering, things have a way of evening out. VW's abominable Vanagon defrost system is a case in point.

Since VW adds cold outside air to the heated air going to the defrost, it is never hot and often not even warm. In the meantime, the rest of your body is getting the hot air from the dash vents or footwells. Soon, you've got that stiffled feeling from breathing hot air.

Try this tip -- move your defrost lever full right to increase the cooler defrost air to the windshield, then tip your visor down about 20° from horizontal. This has the effect of directing some of the colder windshield air right into your face.

Personally, I like to have cool outside air in the face while the rest of the car is warm. MBenz has that option on one set of dash grills, and the old German Ford Capris (circa early '70s) had a through-the-instrument panel vent that put unheated air in the driver's face. Good ideas, both. Too bad VW isn't that smart, but their lousy defroster can make up for it a little bit!

[This message has been edited by Capt. Mike (edited 12-24-2000).]


New member
I have an 88 Westfalia, and have a couple of questions regarding the heater controls. All of the stuff I have read indicates that the 1st lever controls air to the defrost vents, 2nd lever controls coolant flow through heater core. On my Vanagon, the top lever does both, 2nd lever does nothing. If I want heated air at the dash vents or the footwell, I need to move the top lever to the right, and temp goes up as air at defrost vents increases. I can think of no reason why the previous owner would have configured the controls this way. Any thoughts on this before I restore them to the 'standard' configuration? Thanks...

Capt. Mike

You may find it wasn't something the PO did, but is the result of the two levers getting stuck or damaged and moving the cable together. They are sheet metal arms on a common axis. Returning to stock makes sense, despite the flaws in design. It's better than the alternative.


New member
Previously, I sent a post regarding my heater controls, specificall, the top lever doing nothing, and the 2nd lever controling both temp, and windshield air. well, it turns out that the P.O. had both control wire connected to lever 2, as it has holes in both positions. simply moving the offending control wire to it's correct lever solved the problem. Simple, eh?

Capt. Mike

kallen123 Junior Member posted August 14, 2002 08:54 PM

Can someone shed some light on this? I have a pop-top weekender so I have no A/C vents running up the middle. However, along the passenger side there is a vent that runs above the sliding door. It doesn't appear that these are routed to the A/C unit. And I took a peek inside and there are actually wires/cables and some foam inside?!

Is this vent for show or can I get the A/C to blow through it. It sure would be great because the A/C doesn't reach the passenger/driver area too well.

Thanks for any insights!

kallen123 Junior Member posted August 18, 2002 07:57 AM

Mystery Vent on a '90 Westy

19 reviews and no reply...can someone at least let me know if the vent in question has any function in their Westy? Thanks.

MWS Member posted August 20, 2002 03:23 PM

I may stand corrected, but these 2 vents above the rear sliding door are linked to your heating system. If you open your passenger door, you will see an a hollow channel running through the middle of it. This provides an air channel linking the rear vent to the front distribution boxes. Your bottom heater slider controls the airflow to these rear vents.

I don't know whether you can link it up to the AC. European Westys rarely have it - it's cold enough here already! Should be possible with the correct ducting.

TJ Hannink Member posted August 20, 2002 05:41 PM

The vents above the sliding door are connected to the fresh air intake at the front of the van via the heater control box. They are fresh (outside) air only outlets and use the openings in the door and the pillar behind the door to route the air to the vents. The flow to those outlets is controlled by the bottom lever of the heater control, all the way left is open, all the way right is closed.

On a non-Westfalia Vanagon, there are functional fresh-air vents on both sides of the van above the sliding door and middle window. The ducting system is also in place on the drivers side of a camper, but the vents haven't been cut in the cover where the light mounts and the flow of air into the door should be blocked by a sandbag inside the duct directly under the fuseblock.

I toyed with the idea of routing the outermost passenger side A/C duct into the rearmost fresh-air vent. In fact, I mocked up a duct out of plastic that connected the two openings. I turned on the A/C, opened the passenger door and felt the amount of airflow coming out of the vent in the door jamb and wasn't impressed, so I gave up on that idea.

This is what I have done so far to my camper to help the AC to work properly in hot weather (in no particular order):

1. I removed the upper rear cabinet and the evaporator cover panels, then pressure washed the evaporator from the inside of the van, clearing out all of the dust. I did mine while it was in place without disconnecting any of the freon lines, using a lot of plastic sheeting to protect the interior. I installed filter material between the evaporator and the rear intake grill on re-assembly to keep it clean.
2. I also make sure all the fins on the input of the evaporator are straight.
3. Make sure both evaporator fans are working.
4. Re-sealed the plastic evaporator housing panel mating surfaces with new weatherstripping and stainless duct tape.
5. I added some foam inside the vent housing to channel all the air to the front vents.
6. Cleaned the radiator and condensor from the spare tire well-out.
7. Filled the open area of the poptop to keep the cool air from getting lost in the opening. I use a windshield sun screen for an RV. It also blocks the sunlight from the skylight.
8. I keep my my back curtain closed in an effort to keep the area behind the back seat as cool as possible.
9. Get the darkest tint possible on all the windows.
10. Make sure the rear heater is turned off.
11. Make sure the front heater is turned off.
12. Block off all the air flow through the front heater/plenum. I have some foam rubber blocks cut to fit in the openings of the heater vent cover in front of the shifter.
13. Insulate the floorboards, especially the area in front of the shifter.
14. Park in the shade wherever possible.
15. Get an indoor/outdoor thermometer and mount it where you can see it easily, and monitor how the system performs. Mine will cool off at an average rate of 3F degrees per minute. That seems great until you get in the van after work at 5pm and the inside temp is 135F and the outside temp is 109F because its been parked in an unshaded asphault parking lot all day. My van is comfortable at 77F-80F so it takes a while to get to that point. I find that opening the roof vent about 1" and rolling down the front windows 1/2 turn will keep the inside temp around 120F on the hottest days here, so I try to remember to do that when I park for a long period of time.

Tim Hannink
Winter Park, Florida
Goldibox - 1987 Vanagon Camper, Wolfsburg Edition
[url[/url] Vanagon Album


New member
My spin on this thread: as a Van newbie I've scratched my head (in the dark) at the lack of backlighting for the heater/vent controls and auto transmission shift position indication. Is this lighting missing from the design, or do I just need to get tear into the dash and shift lever housing and replace bulbs? If there's nothing back there, are there any proven (and cost-efficient) procedures for adding backlighting in these two areas?

[This message was edited by Museeuw on November 20, 2002 at 10:49 PM.]

Capt. Mike

What year & model? See site Guidelines. I presume Vanagon, which has dash lights to illuminate the heat/vent controls per the wiring diagram in the Bentley for your year.

The factory A/C does not have a light. How to install one is posted as a separate topic on this forum.

A/T tranny lights, wrong forum.


New member
87 Vanagon Wolfsburg. Tore it apart since I posted the original and found the the two blown bulbs in the shifter housing and one set of dead leads behind the heater/vent control panel. The latter will have to wait until I have time, patience, and daylight to get behind the dash with my Fluke. Thanks.


New member
After about 10 years of driving my '85 Westy, I realized that the knobs on the 2nd and 4th heater and fresh air control levers have a sharp ridge on each side. The sides of the 1st and 3rd control knobs are smooth. This is real handy to know when you're fumbling with the levers in the dark or can't take your eyes off the road.


New member
I have an '80 Vanagon with only three controls on the heat adjustments. I think I have figured these out somewhat. However, the heater boxes were unhooked when I bought the vehicle and I hooked them up today. So far so good. I have heat. However, when I first drove it after hooking up the heaters the box where the heat comes out make a terrible racket and some acorns and such came out. My question is this. How much air flow is normal coming out of these vents? I have heat coming out of them now, but little air flow. I also wish the fresh air on the defrost would be different, but as in previous posts I guess it is just something they did on these things. Fred


New member
Got a lot more acorns out of the duct work and now have good heat and air flow. The guy I bought it from didn't drive it in the winter and had left the heat unhooked (?). I did block off the fresh air flow vent to the defrosters and such. Is there a downside to doing this? Fred

Capt. Mike

Transferred to consolidate like topics.

Fresh air gaskets/door channel

elwhawoods Junior Member posted March 01, 2004 04:08 PM

I find no more specific category for this question: Is there supposed to be a louvered vent "gasket" on the latch side of the driver's-side door opening (where the latch edge of the door contacts the opening in the body panel. I'm told not. It looks to be the same type of air-passage opening as on the passenger's side where my '85 Westy DOES have the louvered gasket. I would not question that the gasket is intended except that on the hinge side of the driver's door there is a COVER on the body-panel opening with an electrical wire pass through. Also, why is the driver's-side panel opening (on the fore edge) covered while the same thing on the passenger's side is not. Thanks for any enlightenment anyone can shed on these questions.
Posts: 2 | From: Elwha ,WA,USA | Registered: May 16, 2003

magowanc Member posted March 01, 2004 09:54 PM

Elwhawoods, This vent is for the fresh air vents to the rear of the van (vents on the passenger side of the vehicle along the top rail).

The air flow is controlled by the bottom lever on the heat controls. Note: The rear vents do not carry hot air, just air from outside. The way it works is the air is collected through the front grill, goes through the doors, and up into the vents.

On the standard vanagon, these vents were on both sides of the van, thus the air corridors through both doors. On the westfalia version there are no vents on the drivers side, so the vent is blocked off at the front of the door. There is no louvered cover for the drivers side door. The louver is to aid the air in making the 90 degree turn to go up the pillar between the passenger door and the sliding door.

With that said, get your dealer to look at illistration 93 on their parts fiche. Parts 13, 16, 15, and 17 will all fit on the drivers side of the van if you are wanting to find plugs for these holes.


icarus Member posted March 02, 2004 12:10 AM

A little further info. The drivers side door vents are plugged (cover with the wires) Therefore all the fresh air is directed to the passenger door and then to the rear overhead vents. (I have also discovered that my rear overhead vent duct was plugged with foam plugs,I'm not sure why) I have entertained the idea of opening up the drivers door vents and directing some of the fresh air to the fridge coils, but haven't figured out how to do it yet.


elwhawoods Junior Member posted March 02, 2004 05:46 PM

Thank you Corey and Icarus. I understand it all now. I appreciate your generous and thoughtful responses. You help make this forum a wonderfully helpful resource to the rest of us Westy folks. Thank you. ...BobB


New member
I have created a one-page cheat sheet for running the Vanagon heating, ventilation and air conditioning. I asked Capt. Mike to look it over, so it should be pretty accurate. I have it as a PDF so it should print on a single piece of paper regardless of computer or printer.
Vanagon HVAC cheat sheet


New member

I just bought a 83 Vanagon and when I looked in the dash I discovered to my horror that some one had unhooked all the climate control cables. Is there a schematic or pic that can help me put this mess back together?


New member
Turn my knobs

Heater Fan Control Knob - 1990 Westfalia

Okay so I've just bought a new to me 234k very well kept westy (interior is immaculate, plastic still on stove!). Unfortunately in a recent 50mile trip I went to turn down the fan speed from 3 to off, but it wouldn't turn past 2. When I turned it back to 3, it turns off, but turns on when turned to 2. I don't want to force it, as I'm freaking afraid it'll snap and I'll wind up having to pull off the entire dash. I'm ordering the Bently Manual as soon as I finish typing, but any help would be greatly appreciated.

PS What/where is the switch for "REAR HEAT Change ON / OFF only seasonally"