Air susp compressor survey....How often does it cycle?

allroadbryan · 05-27-2005, 06:28 AM

I've searched the archives and I cannot find a clear answer as to what is normal operation on the air compressor. I have complained to 2 different dealers 4 times now that I felt the air comp ran too frequently and kind of buzzed. They both told me this is completely normal operation. Here are my air comp symtoms:
1. No drop in height even after 7 days sitting in parking lot so I don't think I have a leak anywhere.
2. When I accelerate gently or hard, the air comp turns on when speed reaches 25 MPH. I can hear the faint comp buzz for about 1 min or so and gradually disappears unless I come to another stop and comp stops.
Can you guys share your observations on your AR with the air compressor please.
Thank You

happy allroader · 05-27-2005, 06:31 AM

gragravar · 05-27-2005, 06:35 AM

allroadbryan · 05-27-2005, 06:43 AM

happy allroader · 05-27-2005, 06:46 AM

But 99% of the time, I've got the radio on. Even with the radio off, the A/C makes too much noise to hear the compressor.

Have I ever heard it? Yes, but it is rare. If I go level 1 to 4 to 1 and use all the air in the tank I can force the pump to come on and then I can hear it.

Oddest sound is when I park the car, unload a heavy load from the back and it "passes air" to level itself.

Some folks have reported buzzing and have tried to find where the compressor is touching the body. I just typed in "noise compressor" in the search box (only allroad) and found 97 posts. You might read those, get some ideas of where to look to see if it is buzzing against something.

paulroad · 05-27-2005, 07:05 AM

Is your system set to manual or auto?

Mine will come on when it cylces but only after it lowers or raises, when the pressure is low in the air tank. But not as often as yours.

allroadbryan · 05-27-2005, 07:17 AM

It's definately something electrical that is going on and off. I come to a stop the noise goes away. You can actually tell when it shuts off. I accelerate and comes back on once it reaches 25 MPH.

glidar · 05-27-2005, 07:20 AM

If my tank is low, it can be noticeable as it turns itself on and off in stop-and-go traffic. If the tank isn't low, I don't notice that the compressor isn't running, so I can't tell you how much it runs.

It's possible you have a leak from the tank upsteam of the suspension valving, so the compressor cycles often without any effect on the suspension level. AFAIK, no one has reported that as a confirmed diagnosis.

paulroad · 05-27-2005, 08:17 AM

Park the car.. raise it up to #4 then down to 1 and up to 4 again...do you get the same sound as you do at 25?

Or: Pull the fuse for the compressor and see if you get the noise at 25 again.

want · 05-27-2005, 08:22 AM

The pressure will increase when the vehicle speed increases. The pressure will decrease when the vehicle speed decreases by opening the release valve.
'001 '006
Term15 Term30 Speed Starter Compre. PressureRelease Accumulator
(V) (V) (0-250) (ignition on) temp. (0-20) valve valve
V V km/h C bar
13.17 13.76 28 Term 50 Off 36 11.39 OFF OFF
13.17 13.76 19 Term 50 Off 36 11.39 OFF OFF
13.17 13.76 12 Term 50 Off 36 11.39 OFF OFF
13.25 13.84 5 Term 50 Off 36 11.39 OFF OFF
13.1 13.69 0 Term 50 Off 35 11.39 OFF OFF
13.17 13.84 0 Term 50 Off 35 11.39 OFF OFF
13.25 13.84 3 Term 50 Off 35 11.39 OFF OFF
13.02 13.54 11 Term 50 Off 35 7.16 ON OFF
13.02 13.32 24 Term 50 Off 35 5.53 ON OFF
13.17 13.84 34 Term 50 Off 35 4.23 OFF OFF
12.95 13.47 46 Term 50 Off 35 14.65 OFF ON
12.95 13.47 58 Term 50 Off 36 14.65 OFF ON
12.88 13.39 67 Term 50 Off 36 14.65 OFF ON
12.95 13.39 77 Term 50 Off 36 14.65 OFF ON
12.95 13.47 82 Term 50 Off 36 14.65 OFF ON
13.02 13.47 87 Term 50 Off 37 14.65 OFF ON
12.95 13.47 87 Term 50 Off 37 14.97 OFF ON
13.02 13.54 84 Term 50 Off 37 14.97 OFF ON
12.95 13.47 78 Term 50 Off 37 14.97 OFF ON
13.02 13.47 73 Term 50 Off 38 14.97 OFF ON
12.88 13.39 68 Term 50 Off 38 15.3 OFF ON
12.95 13.47 60 Term 50 Off 39 15.3 OFF ON
12.95 13.47 54 Term 50 Off 39 15.3 OFF ON
12.95 13.47 47 Term 50 Off 40 15.3 OFF ON
12.95 13.47 39 Term 50 Off 40 15.62 OFF ON
12.8 13.39 26 Term 50 Off 41 15.62 ON OFF
13.17 13.84 18 Term 50 Off 41 4.23 OFF OFF
13.1 13.69 11 Term 50 Off 41 4.23 OFF OFF
13.17 13.84 5 Term 50 Off 41 4.23 OFF OFF
13.1 13.76 1 Term 50 Off 42 4.23 OFF OFF
13.17 13.84 0 Term 50 Off 41 4.23 OFF OFF
13.25 13.84 0 Term 50 Off 42 4.23 OFF OFF

05-27-2005, 06:31 AM	#2
happy allroader AudiWorld Senior Member Garage is empty, add now Join Date: Apr 2003 Posts: 826	Don't know because I can't feel or hear mine running. __________________ http://forums.audiworld.com/picture....ctureid=134225

05-27-2005, 06:35 AM	#3
gragravar AudiWorld Super User Garage is empty, add now Join Date: Apr 2003 Posts: 17,262	2nd. __________________

05-27-2005, 06:46 AM	#5
happy allroader AudiWorld Senior Member Garage is empty, add now Join Date: Apr 2003 Posts: 826	Driving slowly on quiet street w/o radio, yes I can hear it. But normally not. But 99% of the time, I've got the radio on. Even with the radio off, the A/C makes too much noise to hear the compressor. Have I ever heard it? Yes, but it is rare. If I go level 1 to 4 to 1 and use all the air in the tank I can force the pump to come on and then I can hear it. Oddest sound is when I park the car, unload a heavy load from the back and it "passes air" to level itself. Some folks have reported buzzing and have tried to find where the compressor is touching the body. I just typed in "noise compressor" in the search box (only allroad) and found 97 posts. You might read those, get some ideas of where to look to see if it is buzzing against something. __________________ http://forums.audiworld.com/picture....ctureid=134225

05-27-2005, 07:05 AM	#6
paulroad AudiWorld Super User Garage is empty, add now Join Date: Oct 2003 Posts: 18,425	How do you know its the compressor that is going on? Is your system set to manual or auto? Mine will come on when it cylces but only after it lowers or raises, when the pressure is low in the air tank. But not as often as yours. __________________ 4/23/11: S4 Premium Plus, S'Tronic, Nav, Titanium body Original Ride: • Bought New May 2003 allroad 2.7t 6 Speed • Sold @ 217,856 miles on April 23, 2011 -Mod/Repair Log 2400 Miles 5/28/11 New Conti Extreme DWS A/S Tires--smooths out the ride OEM Dipstick--Need to see and smell the oil OEM Rubber Mats--Look better than Stock Carpet and last longer

05-27-2005, 07:17 AM	#7
allroadbryan AudiWorld Senior Member Garage is empty, add now Join Date: Dec 2004 Posts: 1,104	What else is back there that cycles on and off like that? It's definately something electrical that is going on and off. I come to a stop the noise goes away. You can actually tell when it shuts off. I accelerate and comes back on once it reaches 25 MPH. __________________ 2002 Atlas Gray/ 3rd row seat Tint: 35% front/ 15% rear & cargo 402 mod: lowered 10mm front / 8mm rear APR 5.0 ECU 91oct/stock Summer Wheels: 18x8.5 RS6 reps ContiExtreme 245/45/18 96W Winter Wheels: OE 17x7.5 w/Dunlop Winter Sport M3 Family Hauler: me, wife & 3 kids 2002 Honda Odyssey EX-L RES (no mods)

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05-27-2005, 06:43 AM	#4
allroadbryan AudiWorld Senior Member Garage is empty, add now Join Date: Dec 2004 Posts: 1,104	Not even a faint humming with windows up, no radio and on quiet street? __________________ 2002 Atlas Gray/ 3rd row seat Tint: 35% front/ 15% rear & cargo 402 mod: lowered 10mm front / 8mm rear APR 5.0 ECU 91oct/stock Summer Wheels: 18x8.5 RS6 reps ContiExtreme 245/45/18 96W Winter Wheels: OE 17x7.5 w/Dunlop Winter Sport M3 Family Hauler: me, wife & 3 kids 2002 Honda Odyssey EX-L RES (no mods)

05-27-2005, 07:20 AM	#8
glidar AudiWorld Senior Member Garage is empty, add now Join Date: Jan 2004 Posts: 792	It's much easier to hear with the back seat folded down. If my tank is low, it can be noticeable as it turns itself on and off in stop-and-go traffic. If the tank isn't low, I don't notice that the compressor isn't running, so I can't tell you how much it runs. It's possible you have a leak from the tank upsteam of the suspension valving, so the compressor cycles often without any effect on the suspension level. AFAIK, no one has reported that as a confirmed diagnosis. __________________ - glidar ---------------------------------------- My fuel log \| Factory trailer hitch installation guide \| VAG Locator \| allroad FAQ \| Where is we? Repair/Mod Log 11/2008 111000 mi: Replaced window lockout switch block in armrest. Replaced power steering pump. 7/2008 108000 mi: Steering pump bolts left loose after TB change caused bolt to shear and bracket to break, causing ribbed belt to come off. Drilled out & replaced bolt, reinstalled belt. Replaced rotted BPV control hoses. 3/2008: Replaced front axles (Raxles) 12/2007: Continental Winter Contact 225/55-17. 6/2007: Cleared recurring ABS code (by SCR). 4/2007: Replaced turn signal stalk, hazard relay, and clock-spring connector. 2/2007: Replaced EGT sensors. 2/2007: Replaced broken mirror switch. 12/2006: Replaced left front CV boot. 10/2006: Replaced right front air spring. 9/2006: APR. 8/2006: Kumho ECSTA ASX 225/55-17. 7/2006: Changed timing belt, water pump, etc. 4/2006: Replaced leaking coolant expansion tank. 2/2006: Replaced front rotors & pads (Zimmerman plain & Mintex RB) 11/2005: Falken Ziex 512 trashed at 15,000 miles 3/2005: Left front air spring, compressor & control unit replaced under warranty. 2/2005: Installed H-sport sway bars. 8-12/2004: Left front fully deflates 50% of the time; remains inflated 50% of the time. 8/2004: First suspension deflation (left front). Reinflated fine; no codes. 7/2004: Replaced tie rod ends with ECS heavy duty. Installed trailer hitch. 6/2004: Falken Ziex 512 225/55-17. Front lower left control arm replaced by dealer -- didn't fix squeek. 4/2004: Front mud flaps 3/2004: 710N BPVs 3/2004: VAG-COM 2/2004: Servotronic 605 relay removed 1/2004: 2001 allroad 2.7T 6-speed Highland Green with third-row seat Squawk List as of 10/2007 Lumbar adjustment inop on driver's side Safety switch on armrest for rear windows won't stay down. Missing lines in DIL. Instrument panel/glareshield squeek. Intermittent HVAC fan noise. Peeling passenger armrest. Erratic rear wiper. Fart sound from (yes) the rear. A/C smell. Rear bumper paint chipped by backing into sign. Sun visor plastic bearing broken off. Clunk from rear suspension. Windshield washer doesn't spray driver's side much. Slight on-center play in steering. Speaker in both driver-side doors cut out intermittently.

05-27-2005, 08:17 AM	#9
paulroad AudiWorld Super User Garage is empty, add now Join Date: Oct 2003 Posts: 18,425	I suggest: Park the car.. raise it up to #4 then down to 1 and up to 4 again...do you get the same sound as you do at 25? Or: Pull the fuse for the compressor and see if you get the noise at 25 again. __________________ 4/23/11: S4 Premium Plus, S'Tronic, Nav, Titanium body Original Ride: • Bought New May 2003 allroad 2.7t 6 Speed • Sold @ 217,856 miles on April 23, 2011 -Mod/Repair Log 2400 Miles 5/28/11 New Conti Extreme DWS A/S Tires--smooths out the ride OEM Dipstick--Need to see and smell the oil OEM Rubber Mats--Look better than Stock Carpet and last longer

05-27-2005, 08:22 AM	#10
want AudiWorld Senior Member Garage is empty, add now Join Date: May 2003 Posts: 1,024	I think that "how often" is dependent on the road conditions. The following is one of my log data. The pressure will increase when the vehicle speed increases. The pressure will decrease when the vehicle speed decreases by opening the release valve. '001 '006 Term15 Term30 Speed Starter Compre. PressureRelease Accumulator (V) (V) (0-250) (ignition on) temp. (0-20) valve valve V V km/h C bar 13.17 13.76 28 Term 50 Off 36 11.39 OFF OFF 13.17 13.76 19 Term 50 Off 36 11.39 OFF OFF 13.17 13.76 12 Term 50 Off 36 11.39 OFF OFF 13.25 13.84 5 Term 50 Off 36 11.39 OFF OFF 13.1 13.69 0 Term 50 Off 35 11.39 OFF OFF 13.17 13.84 0 Term 50 Off 35 11.39 OFF OFF 13.25 13.84 3 Term 50 Off 35 11.39 OFF OFF 13.02 13.54 11 Term 50 Off 35 7.16 ON OFF 13.02 13.32 24 Term 50 Off 35 5.53 ON OFF 13.17 13.84 34 Term 50 Off 35 4.23 OFF OFF 12.95 13.47 46 Term 50 Off 35 14.65 OFF ON 12.95 13.47 58 Term 50 Off 36 14.65 OFF ON 12.88 13.39 67 Term 50 Off 36 14.65 OFF ON 12.95 13.39 77 Term 50 Off 36 14.65 OFF ON 12.95 13.47 82 Term 50 Off 36 14.65 OFF ON 13.02 13.47 87 Term 50 Off 37 14.65 OFF ON 12.95 13.47 87 Term 50 Off 37 14.97 OFF ON 13.02 13.54 84 Term 50 Off 37 14.97 OFF ON 12.95 13.47 78 Term 50 Off 37 14.97 OFF ON 13.02 13.47 73 Term 50 Off 38 14.97 OFF ON 12.88 13.39 68 Term 50 Off 38 15.3 OFF ON 12.95 13.47 60 Term 50 Off 39 15.3 OFF ON 12.95 13.47 54 Term 50 Off 39 15.3 OFF ON 12.95 13.47 47 Term 50 Off 40 15.3 OFF ON 12.95 13.47 39 Term 50 Off 40 15.62 OFF ON 12.8 13.39 26 Term 50 Off 41 15.62 ON OFF 13.17 13.84 18 Term 50 Off 41 4.23 OFF OFF 13.1 13.69 11 Term 50 Off 41 4.23 OFF OFF 13.17 13.84 5 Term 50 Off 41 4.23 OFF OFF 13.1 13.76 1 Term 50 Off 42 4.23 OFF OFF 13.17 13.84 0 Term 50 Off 41 4.23 OFF OFF 13.25 13.84 0 Term 50 Off 42 4.23 OFF OFF

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05-27-2005, 08:22 AM
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