Some kind of pump runs randomly when vehicle is parked

[Mizagorn]

Hello all! I have been searching for this problem for over 30 minutes and can't find anything. Perhaps I am just using the wrong search terms.

My son got a 2001 Eddie from his grandmother. Everything is just fine, except...

There is some kind of very loud pump or compressor (it sounds just like a small air compressor you might have in your shop) that randomly comes on every once in a while, and it's also doing that while the vehicle is parked and not running. While the grandmother never had a dead battery issue (as she drove it practically every day), my son does not yet have his license so the vehicle rarely gets started.

I tried to move the vehicle today, and had to jump it because something drained the battery again. I tested for leeches a couple of weeks ago but I found nothing, so I'm assuming it's whatever that pump-sounding thing is that comes on even when the vehicle is parked and no key in the ignition.

Apologies if this is a simple question but I'm making no progress on my searches. I'm not usually stumped!

Thanks very much for your time.
Terry

 

[EB4X]

The only thing that comes to mind would be some aftermarket add-on electric cooling fan that comes on immediately after shutting engine down.... some makes had that setup a while back. Not sure why someone would add that to an Explorer....but......
And as stated those would ONLY come on upon immediately after shutting off engine and just run for about a minute or so.

 

[Mbrooks420]

Look in the rear cargo area behind the cover on the side of the truck. Look for an air ride off switch, it’ll look like a circuit breaker.

Most likely you have rear air ride and something is leaking. Remove it all, and replace with standard shocks. Don’t forget the 5th shock.

 

[EB4X]

Look in the rear cargo area behind the cover on the side of the truck. Look for an air ride off switch, it’ll look like a circuit breaker.

Most likely you have rear air ride and something is leaking. Remove it all, and replace with standard shocks. Don’t forget the 5th shock.

Awww.....that's right.....I forgot about those being on some Explorers..... good call...

 

[Mizagorn]

Look in the rear cargo area behind the cover on the side of the truck. Look for an air ride off switch, it’ll look like a circuit breaker.

Most likely you have rear air ride and something is leaking. Remove it all, and replace with standard shocks. Don’t forget the 5th shock.

Thanks so much for this! And apologies for the delay. I will check that out as it sounds very reasonable. Very much appreciate your time!

 

[CDW6212R]

The ARC system was rear only in 99-01's, optional on all 4dr's, standard on none, unlike 95-98's. The rear shocks are still available, aftermarket or some people even have the OEM shocks(I think they made a ton of those). I've seen them for about $100 for a pair, which is a great price if they do what they are supposed to(top quality and don't leak(how old are they)). I installed two new ones from Ford at $90 each, in 2006, and after 77k miles, bought another pair from eBay for about $95 for two.

The leaking is likely going to be a small leak at the air line connections, and fortunately there are not many air lines on the 99-01's. The 95-98's had four air shocks, and long air lines, up to the front etc. The rear ARC system you can see everything all close together around the shocks and the spare tire. The line connections are small and have tiny seals in them, the same kind as many stock Ford air systems. So finding the little components may take some time, but they are serviceable.

The real keys at this age are the compressor, and the height sensor. If the compressor doesn't work, that's expensive and tougher to find. The height sensor is just a small group of parts, but fragile plastic with movement joints that can wear out, and those are really hard to find.

So for the rear only ARC, I suggest trying to keep it functioning, it is handy to be able to load heavy things in the back, and the ride height maintains the normal level all the time.

 

[boominXplorer]

Ive seen the abs modules short and do the same thing. Happen to mine before.

 

[OSUChE]

Ive seen the abs modules short and do the same thing. Happen to mine before.

Look in the rear cargo area behind the cover on the side of the truck. Look for an air ride off switch, it’ll look like a circuit breaker.

Most likely you have rear air ride and something is leaking. Remove it all, and replace with standard shocks. Don’t forget the 5th shock.

These models are equipped with a relay that cuts power to this and other electric systems after 40 minutes (time?) to prevent draining the battery. Might be an issue with this...