So, back in the wonderful world of EAS issues. Dropped to the bump stops and compressor not running. New compressor and I find that something is calling for the compressor basically constantly. Gallery pressure is decent, slowly goes down but nothing is visibly leaking fast. So. I have the ID tool and I'm trying to figure out if I can use it to tell me what is calling. However I have tried looking at almost all live suspension values and nothing seems to indicate what is calling for the compressor to cycle. Any experts out there have any tips on how to locate the issue? Cheers.

 

...is your new compressor the same brand as the prior one?

 

Well the suspension computer would be calling for the compressor to run if you are on stops. Jump the compressor relay and see if it fires up. Also do you have lift rods installed?

 

Yes, same as the original.

 

I should have added more information. The vehicle did rise up to ride height and can cycle through all 3 heights. ID tool reads ride height at 0 across the board, no deviation. So I don't understand why compressor is still running. Something is calling for air. I guessing one of the valve blocks. I pulled out the computer fuse for the night. We'll see what the suspension looks like in the am.

 

I guess you need to describe things better. Also there are no "calls" for the compressor to run, so totally confused as to what you are even talking about. The valve blocks are just valves driven by the EAS computer with the center block ONLY allowing the reservoir to fill or empty.

The EAS on command checks heights and raises accordingly if request. Often it will start or end a cycle with an exhaust "fart" to bleed off gallery pressure first and allow the compressor to run without fighting the gallery pressure. Then within a half second it, once the compressor is running, the center valve opens to the reservoir and dumps air into the gallery to assist the compressor by supplying lot of air volume quickly and make height adjustments fast. If the reservoir is low the vehicle will take longer to raise. If its flat out empty you may even get "vehicle rising slowly" message. Once height is achieved the compressor continues to operate until the reservoir is filled back up for the next height change. That pressure is just under 250psi. This can take a minute or so. Then it shutdown, again often with an exhaust fart to bleed excess pressure in the gallery. If the compressor is running non-stop for minutes on end then I would suspect a faulty relay. If that happens the safety design of the exhaust on the compressor will work to bleed off the air being generated since the reservoir will be closed and so will the front or rear valve blocks.

 

If there are no "calls" for the compressor to turn on then how does it know when air is needed or not? Something has to be saying to turn on and off. If it is the computer then something is telling the computer. Otherwise there is no understanding of when it should cycle. My understanding is that gallery pressure is not a determining factor for when the compressor runs. Maybe it is reservoir pressure?

 

Ok, I've read through a few other posts on the forum about this constant running issue and have a few ideas to try.

 

The EAS computer monitors everything and triggers the compressor relay...... like pretty much any EAS system I have worked on in 20 years. There is nothing that "calls" and requests the compressor to run or tells the EAS computer to run. Its just sensors, there are no sub-systems. Reservoir pressure is not monitored. Gallery pressure by design bleeds out and is, as mentioned, vented at times. The only time pressure is monitored is when the compressor is operating, and that is done to evaluate several perimeters for system health and operation.

 

As always I appreciate your input and willingness to try and help. Thank you. Some set of circumstances makes the ECU decide to open the relay for the compressor to turn on and in turn to close it to make it stop. That is what I mean by call. My new compressor, even after it has lifted the vehicle to proper ride height will run until it hits max temp and then it will shut off. When it cools to operating temperature it comes back on again. Over and over. It won't stop running. I believe this is probably what burnt out the old one. It didn't always do this. I'm trying to figure out what is causing the constant run. Cheers.