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Discussion Starter #1
ok.. i know how the air regulator works and what it does..

im just wondering now about the shutter inside it.. does it move because it gets hot.. how does that work.. i know there is a heating element inside the unit.. can someone further explain it to me..
thanks
 

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ok, the shutter is connected to a bimetalic strip of metal coiled into a spiral spring.
as the coil heats up, the 2 metals expand at different rates, and the coil unravels (or rolls tighter, depending on metal placement), and moves the shutter.

the bimetallic coil is heated by both the engine coolant and by an electric heater connected to the ECU. so the AAR is open when the engine is cold, and closes either when the engine gets hot or after a specified time when the electric heater gets hot enough.
this also prevents the AAR from being open long on warm starts when the manifold might be cold but the coolant is warm.

i think the FSM or EFI bible describes its operation in more detail.
 

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Discussion Starter #3
well just so i know that the spring is what the heat affects.. i wasnt sure how exactly it worked.. thanks..

do these go bad very often.. i need to run some tests on mine to make sure its working ok.
 

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In simple terms the shutter opens when the air regulator is cold and closes when it is hot. Easy way to test is to place it in the freezer for about a half hour. The shutter should be fully open or close to it. Then take it out of the freezer and place outside where the sun can hit it or place back on the car and warm the car up to normal operating temp. At this point the shutter should be fully closed. It's not so much a problem if it doesn't open fully when cold, but mainly if it doesn't shut when warm. Reason is that if it is still open then it is sending the signal to the cold start valve to work which will inject extra fuel which under normal operating temp will make the car run rich. On the other side if the shutter doesn't fully open when cold it will just be a little harder to start on really cold days. No they don't go bad often but with the age of these cars more than likely they are bad. On my 77 I had to replace it two years ago. 25 years life for the part I think is pretty good. You might be able to use a junkyard part for quite a few years before it goes bad and they are cheap too. Good luck
 

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An easier test is to not put it back in the car after the freezer, but just hook some wires with alligator clips to the AAR terminals and a car battery. That way, you can see the flap close (and feel the heater working in your hand). It's also handy for testing the AAR. When the flap is fully closed, try to blow through the AAR. If you can, it's no good. My experience with these things is that they are almost all bad on older cars. I had two spares from parts cars that I tested before replacing the bad one on my '76, and they were both bad. So I bought like 5 or 6 of them at half-price day at Pick Your Part and all but one tested bad — that is to say, you could blow air through them when the flap was closed. The only one that worked, and which is on the car now, was a slightly different design out of a 280ZX.
Mpcapps is also correct that most AARs are also heated with a bypass line from the water jacket going to a little 'heater' under the AAR. The only year this is NOT done is on the first-year fuelies, the '75 280Zs.
 

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Just to clear up some stuff:

The AAR and cold start valve/thermotime switch systems are independent from each other. Malfunctioning AAR will not cause the cold start injector to squirt.

The AAR functions like a throttle offset, allowing more Metered air into the engine. The AAR shutter position is adjustable. there's a small post on one side with a small nut and washer. loosten the nut and move the post (it will pivot with spring loaded resistance); this moves the shutter around.
AAR adjustment:
so hook up the AAR to a battery and see if the shutter closes. if it doesn't, loosten the nut, and change the location of the post so you can't blow air through it anymore. then let it cool and make sure the shutter opens some.
AAR's probably don't go bad, the bimetallic strip proably just loses its springyness; and that's probably why they put the adjustment screw on there.
additional notes on the AAR's operation: the valve will close when it has enough THERMAL energy, or enough TIME has passed (letting the electric heater in the AAR close the shutter). Thermal. Time. sound familiar?


The Cold Start Valve works under certain conditions only, depending on the position of the ignition key, and on its partner component the ThermoTime switch. The thermotime switch operates as an enable for the cold start valve: if the engine is cold, and if the system has been powered for less than 7 seconds (if memory serves), the cold start valve is allowed to operate. the system (cold start inj and thermotime sw) only gets power when the ignition key is in the "start" position.
The seven seconds is to prevent flooding the engine with the extra injector during extended cranking.

The AAR has the thermo/time functions built in; the cold start injector is simply a fuel injector; it needs an outside component to control its operation.
 

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I learned something here

Mpcapps — Noticed that adjusting screw but never tried it. I will try to adjust some of my "bad" AARs now to see if I can make them close off properly. That is, if I have any left. I think I tossed almost all of them after above tests thinking they were all bad!
 

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I need to check blue's tech tips before i respond to questions now; it would have saved me a lot of typing.

Blue: is there any way to tell if the bi-metallic strip has rotated 90deg without opening up the unit? also, does the heater/strip/electrical connector assembly just pull out of the housing? can you rotate and reinstall to fix the 90deg problem?
 

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Discussion Starter #10
ok so i check out the link about the aar.. the metal does bend.. and pushes the shutter.. thats what i thought.. anyway mine isnt in the right position to open that.. mine is moved due to me opening it up.. time to run some tests and see if i can get it back to the right spot.. i cant open the stupid thing though.. so that makes it hard.
 

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Discussion Starter #11
i just got done messing with my car.. finally got it running good..

but.. is the air regulator supposed to close totally.. cause i found that when mine is closed all the way or just a crack.. my car wont run..

im sure the thing is bad anyway.. and when its real cold i will be catching the bus.
 

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If your AAR was disfunctional for a long time, there's a good chance that the previous owner (or you) overadjusted the idle screw on the throttle body.

when you reset your AAR properly it will most likely lower your idle. compensate by properly adjusting the idle screw on the throttle body.

hope that helps.
 
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