AAR Revisited

[Porsche80]

Hey, I have a similar problem only my car idles about 1400-2000 until the engine warms up. No other problems and during the summer it is not real noticable as the outside temp rise, the car warms up faster. My wrench said the AAR was bad. I have a 1980 911SC with 3.0 do you have a spare that you would be willing to part with?

[T77911S]

WOW! i have one off an 80, i just checked the price. WOW! and some are NLA.
i was gonna sell, i may have to re-think it.

[Xander1969]

Most issues here seem to be AAR not closing correctly. I have the opposite issue. Temperature out is in the upper 60s and when I pulled it from the cold engine, it was almost totally closed. I put it in the freezer for awhile and it opened very little, if any. Attached is a picture of it coming from the freezer. Certainly this thing should open further than that? If so, if I take it apart, are there any adjustments/modifications I can make so it will open further?

[jmancool]

My AAR is taking about 20 to 30 min to fully close. I check the voltage at the plug and it has 10 volts at the plug. The RPM starts at 2000 and takes about 20-30 min to go down to 900. Everything seems to be working OK but it just takes a long time for the idle to reduce to base idle. Any ideas?

[Bill Douglas]

Revisited and revisited...

A big thanks Ron.

Jmancool, my car (guilty AAR) was doing that. I pulled the AAR to bits and gave it a clean, not that it was dirty, a light lube, and put it back together, plus cleaned the electrical connectors - works fine

[l_turn9]

The OE Porsche AAVs are really expensive so I searched for an alternative (if rebuilding mine fails) and found this <> It looks identical to the Porsche AAV & I'm pretty certain there would be no difference. Afterall, we're looking for air flow control and nothing more. The little door that controls the air gets 12V and heat from the engine (that's why it rests on the cyl, head sheet-metal) and other than resistance in the wiring - which controls the speed of the movement of the little door - there's little to be different. Prices for these parts have increased recently -now to ~$100 where I found one last year for $60. You may be able to find a better source. Look for a AAV for a 74-79 VW Bus.

The link I included above will be removed - I found a AAV at germansupply.com pn 0 280 140 164. Good luck -

[Gunter]

Prevent confusion.

AAV is NOT AAR!!

AAV has no electrical connection!
AAR has an electrical connection!

Components for cold-start: WUR, AAR, AAV, TTS, CSV.

[Bill Douglas]

Some other cars have CIS, so maybe it's worth looking at Volvos and Saabs at junk yards (LOL, there's enough of them there) for AARs. I certainly wasn't going to buy a new one if mine didn't come right.

[l_turn9]

Thanks for pointing out my mistake. While the part I suggested is a AAR, I mistakenly said AAV. The AAR in linked looks very much like the ones on our Porsches. But I believe the bodies are made of plastic instead of metal.

[Xander1969]

It appears Pelican Wire Co no longer carries the exact wire mentioned to do this project. Is there an alternate that will work or somewhere else that carries it?
Thanks

[Vereeken]

I need to ask.

How do you get that plug out to gain access to the bimetal attachment?

Am I not afraid to say that I do not have an idea on how to get that plug out besides drilling it out but then I would need to make up a new plug...

Michel

[l_turn9]

those of us who are "thrifty" but less electrically talented as some here, I suggest checking out the AAR installed on many VWs - especially the late 80s Transporter. It is around $75 but would have to be checked to determine the opening temps and the delay for the WU Idle. But it's a LOT less expensive vs the 911 part number!

[groovydude]

I know the original post for this thread was a long time ago, but I think it's worth reviving. My belief is that the AAR in stock form is way too conservative, in other words it stays open too long. I think the OP had the same idea, and his alteration may shorten the time open, but it also reduces the air flow when cold. Wouldn't lowering the resistance of the coil be a better option? This would allow for the same position of the plate with the hole in it, but just close the plate faster. If a resistance of 17 ohms causes the plate to close at 2 minutes, and 33 Ohms causes it to close at 5.5 minutes, perhaps something around 28 Ohms would be ideal. Has anyone tried messing around with this?

[universeman]

Digging into my AAR...question - when it closes from warming up - does it close/block off completely ie 99% to 100% blocked? Or does a little bit of the moon stay open?

[boyt911sc]

Originally Posted by universeman

Digging into my AAR...question - when it closes from warming up - does it close/block off completely ie 99% to 100% blocked? Or does a little bit of the moon stay open?

Jason,

First measure the resistant value (Ohms) of your AAR. When cold, it should be about 1/4 to 1/3 opening like the shape of a quarter moon. When warm, it should be totally closed. Shine a light through the hole and verify it is totally closed after 4 - 5 mins. after supplying 12 volts to the AAR.

Tony

[iboughta911SC]

I've read this forum and think it is a very helpful thread. Interestingly, my 81 911SC AAR, the one with power, seems to "open back up" in very cold weather. What I mean is the car is kept in a 60F heated garage. This morning as an example, it was 30F outside. I started the engine, it idled around 1,500 for about 25 seconds, and dropped down to about 1,050. Leaving the neighborhood, idle was about 1,050-1,100. After a few miles of highway driving (6-7 minutes) in 30F temperature, as I pulled into the parking garage at the office, idle was back up around 1,400. As if the cold air overtook the temperature of the AAR surpassing the engine heat transfer and opened the valve back up?

When it is above 50F, my idle remains around 1,000 after initial 25 seconds of AAR additional air.

Thoughts?

['78 SC]

Originally Posted by iboughta911SC

... Interestingly, my 81 911SC AAR, the one with power, seems to "open back up" in very cold weather. ...

The AAR is not the only device that can increase idle. Have you confirmed the AAR is re-opening? A screwdriver, a mirror and a light are all it takes to remove a hose and confirm.

[1987 Porsche]

Anyone know where to order the correct resistance wire for the bi metallic strip? I know the OP said the pelicanwire company but another poster said they no longer carry it. Thanks


Lou

[ahh911]

Ron (mysterytrain),

This was useful. I too had the incorrect aar installed that exactly matched your situation, 1981sc usa. 209 aar when it should have been a 218.
Rather than take it apart, I simply added a roughly 7 Ohm, ~5W rated resistor, or thereabouts in series with the 12V power feed to the AAR. Then I pressed the pin in to close the air gate, after ~5.5 minutes it closes. What I'll do in the future is put the aar in the fridge and heat it in there and adjust the pin to the point where the element can close the door, that should be interesting. Anyhow, the car's idle on cold starts stay very nicely bounded between 1200 and 950rpm for the first 10 minutes of driving, thus far. (I had extra Bosch connectors lying around so I plugged in an extension to the original wiring with the 7 Ohm power resistor spliced in, no damage to original wiring).

Not sure if the heating element power is the only change between the later and earlier designs. Is the spring the same? Window on brass slider? Still one heating element? I'd think so. Curious to know if the spring is interchangeable? I like the door to stay open when a little warmer but no open so much when cold.


-Edit: Increased full range of temperature operation on the wur209.

Across the 7 Ohm resistor that is in series with the aar I added a relay that would time out after 3 minutes and then short the resistor thereby returning the aar to full heating capability. I assumed ~ 55C the door should still be open for my needs and knocked the pin accordingly. In Summary, wanted the door to close at -12C (operated the aar in the freezer) but still wanted open when fairly warm. The heating element was made to operate ~ 1/2 power for the first 3 minutes and full power the rest of the time to ensure the air door completely closes. The car can now sit for 2-3 hours after a heat soak and the rpms will not drop for the first several minutes of driving, it might rev slightly higher at low temps but so far so good, haven't resorted yet to dremmeling a slight notch into the 1/2 moon to limit cold temps rpm while retaining some pass through air at higher temps, and finally full closure over all temperatures. -


This work is for a very particular set of circumstances.


fyi:
The prior owner had a tapped screw in there that after reading your post I understood he used to pull the plug out.

picture below shows plug on end of aar removed by knocking out the tapped plug, sealed up the thread on re-assembly, but all this is probably not necessary for this job.
I don't suggest tapping unless you plan on cleaning the insides real good, my rivets were all intact, hopefully whoever did this blew out the chips.

[jrwilson]

Are there any tutorials anywhere on making your AAR adjustable? I'd like to mod mine to make the cold air hole size smaller.