The AAR gets 12 volts anytime the engine is running. It operates both on engine temperature and the heater speeds up the process from a cold start. It operation is very slow so it is not the cause of any erratic operation. Do make sure the wiring is not swapped with the throttle position switch if it uses the same connector. If swapped the switch is now toast and with the AAR connected to the switch connector the ECU will always think the throttle is closed. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Skip
Sent: Wednesday, August 29, 2012 9:05 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Auxiliary Air Regulator - Testing - Digijet

'84 Westy, Digijet, 1.9L case with a 2.2L GoWesty kit

 I've often suspected a less than ideally working AAR.  My cold idle is sometimes wonderful, sometimes choppy, sometimes "wandering" (up and down).

 It's so darn hard to reach the AAR connector without taking out half the right side of the engine ancillaries.

So I have a used spare on the bench, as well as a charged spare battery.

Question:  How can I test the open/close mechanism of the spare AAR?  Can I simply power it by connecting leads from the battery to the "Heating coil terminals" on the AAR?  And when I charge it, should the "gate" close or open?

Please advise and thanks!

Once I have the answer I'll dig into the one on the engine and check the installed AAR.  Bentley 24.28 provides cryptic instructions (and I need to wait for the engine to cool to "pinch the hose").  Regarding 24.28, what is the voltage measurement that I should see when I check the connector, and ("with the engine running") should the engine be warm or cold when I measure voltage?