Air Suspension Compressor constantly running

AUSTIN LEIVO

MEMBER
2001 FORD EXPEDITION
5.4L
V8
4WD
AUTOMATIC
189,500 MILES

Hi there, I have been replacing the air suspension system on the vehicle listed above I have. It’s the Eddie Bauer model with the 5.4. I recently snagged a 1999 Lincoln Navigator air suspension compressor and installed that to replace the OEM one, we just used the same old drier which I know functions because the rear air springs would lift up after the faulty compressor decided to kick on. What I’ve noticed is that the replacement compressor constantly runs, but it’s not filling any air to the rear air springs that I just replaced about a week ago. The connector to the Air Suspension Relay was melted so we had to rewrite a new connector piece from another expedition up to it. When plugged into the relay the compressor runs, when unplugged it shuts off, and there’s no other way to turn the compressor off at this rate. I’m trying to figure out why the compressor will constantly run and not fill up air to the rear air springs.

7 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

This is going to be tough because you changed the system. However, let's give it a try. When you indicate the rear won't pump up, are you certain there are no leaks? Also, have you tried a mechanical or electric reset?

If you look below, the first two pics are the mechanical reset. The last three are the electronic reset.

Let me know if you have already tried this. As far as the compressor running, if there is a leak and the rear height isn't reached, the height sensor will keep it running.

Take care and let me know what you find.

Joe

See pics below.

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Thursday, September 9th, 2021 AT 6:43 PM

AUSTIN LEIVO

MEMBER
4 POSTS

We tested the air lines and found no leaks. Before the system change the rear would pump back up no problem until the compressor stopped functioning. The solenoids do not click consistently when messing with the ride height sensor in the back. The one under the driver door stopped clicking but the air springs still click on attempting to allow the air in.

After rewiring the connector to the relay the compressor stopped running constantly. Only when the doors are closed on the car. I’ve read that this is normal until it reaches optimal ride height, however since the back will not lift, the compressor will just keep running now. That tells me the system is communicating with the compressor and the relay properly, unless that’s the exact opposite of what that means.

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Thursday, September 9th, 2021 AT 7:02 PM

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

What you are saying makes sense. Do me a favor. Take a look through the diagnostics below. They are specific to the rear air suspension failure. See if there is something there that helps.

It will require a scan tool that can actuate the compressor system.

Let me know.

Take care,

Joe

See pics below.

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Thursday, September 9th, 2021 AT 7:49 PM

AUSTIN LEIVO

MEMBER
4 POSTS

This is going to be troubling since all I have is an OBD reader that can reset codes and test other categories. I’m not sure if it can test air suspension but I’ll check it out in a bit.

If I do not have the tool, what would be my next course of action for diagnosis/fixing?

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Friday, September 10th, 2021 AT 4:20 AM

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

That's a good question. If you follow the diagnostics, it should lead you to the problem.

Let me know if you are able to get a scan tool that can do what is needed.

Take care,

Joe