Air compressor working when car is closed

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Dec 18, 2015 | 05:57 AM

Stanislaw

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Air compressor working when car is closed

Hi Guys...
98 Navigator 4x4.
I know I have a problem with leak from the front suspension (probably struds are worn), and I have apropriate code on the computer for this. This results the idiot lamp after a few miles... But so far I can live with this problem...

As for the rest of operations it works fine. It rises when started, it goes down when turned off...Valves working fine

But... I discovered something strange... Car is in park possition, keys in my pocket, car closed as usual for the night.... And every few minutes (5-7 I'd say) the air compressor starts. It is runing for a 20-30 seconds and switch off it self... After a few minutes it repeats... There is no valves sound and no change in height... Just the compressor works - not whole system...If i open the car (and whatever door) during the compressor cycle, it stops (as it should). The result is that after the night, my battery is empty...

For me, it looks like it doesnt know that car is parked and stopped. It thinks it is running... But how ??

Do you have any idea where to look ?

Dec 18, 2015 | 10:21 AM

alloro

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There is a minimum height the system will maintain. The leak is causing it to drop below that minimum and is triggering the compressor to pump it back up.

Dec 18, 2015 | 10:37 AM

Stanislaw

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I thought so... but it stays relatively high... It is not laying completly down... My leak shows only when parts (struds) move... When left alone - it keeps the height front and rear ok.
And... that strange pumping not causing any changes in height... selenoids and valves do not work then..only compressor.

Dec 18, 2015 | 10:51 AM

alloro

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Quote:

Originally Posted by Stanislaw

that strange pumping not causing any changes in height

Are you positive? It can be hard to judge by eye, I usually have to take measurements.

Dec 18, 2015 | 11:36 AM

Stanislaw

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Yes I'm... When Normal operation - I'm in the car, engin running and so on, pumping, means going up... But in the case I'm reporting, when car is left alone, pumping does nothing. No valves sound, and no any change - I did measurements... Not a single move then...Just compressor working...

Dec 18, 2015 | 01:28 PM

2trux

Mountain Pass

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From: Albuquerque

When I had a leak in the rear of mine it did the same thing. The compressor would cycle on/off until the battery was dead then the truck would drop all the way down.
Repair the leaking part before you spend too much brain sweat on this. The front air shocks on the gen1 trucks are not that pricey, plus you get new shocks to boot. The installation is also very simple, not much harder than just replacing shocks.

Dec 18, 2015 | 03:22 PM

pdqford

Logistics Pro

Joined: Jan 2001

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From: Central NYS

Quote:

Originally Posted by Stanislaw

keys in my pocket, car closed as usual for the night.... And every few minutes (5-7 I'd say) the air compressor starts. It is runing for a 20-30 seconds and switch off it self... After a few minutes it repeats...

Do you have any idea where to look ?

The air suspension system is live for 40 minutes after the ignition key is turned to "OFF". During this 40 minute period it may activate some components.

So wait 50 minutes after key "OFF" and see if it still happens. If it does, turn the air suspension switch to "OFF". If that stops the compressor from cycling you need a new air suspension control module.

If the compressor continues cycling with the air suspension switch turned off, unplug the air suspension relay under the right front headlight.

If unplugging the relay stops the cycling, you need a new relay. If it doesn't stop cycling with the relay unplugged, monitor the grey/red stripped wire that powers the compressor with your meter. It is shorting to power some place.

Good Luck!