Need to know how to test air suspension compressor and relay relay

The rear end on my 1999 Expedition has gone down for the second time in 2 years. Last time I had this fixed it cost me $1300, so I want to be able to do some basic testing and resolution myself.

First thing I noted after the rear end had gone down was that the hose going to the driver's side rear suspension air bag had snapped off and was dangling. I cut this back to pliable rubber and re-attached it. I suspect that when this came off the compressor was working overtime and either it or the relay blew.

When I switch on the ignition I do not hear the compressor running. Also, just as an idiot test, I detached the hoses to feel for any air, but got nothing so assume that it is most definitely not running.

I have checked the fuses and they are ok. I have also checked the 50A relay and that is OK and proved it further by swapping with another one in the box.

I have located both the compressor relay and the compressor /drier. But I need to now know how to test these. From my searches online I discovered that the control box is supposed to send a ground to the relay to activate it, but I don't know which of the 4 pins this is supposed to be applied to.

I also get a reading of about 10.6 volts on the red wire to the compressor regardless of if the ignition is on or off so I suspect that the relay passes a ground to the compressor to complete the circuit??? The compressor has 4 wires, red and black, and blue and white. The relay has 4 connections labelled A, B, C and D

Could anyone provide a wiring diagram or instructions on how to test these???

I did search this forum but did not find any similar requests.

Thanks

I managed to figure out what was wrong. Using just plain old common sense I figured that the red and black wires going to the compressor were power so I jumpered these directly to the battery and the compressor ran, so I figured it was OK.

I tried to use a ohm meter on the relay to see if there were shorts but couldn't figure that out. I switched the car on and everything else seemed to run fine, all the displays looked OK, so I figured the computer was fine. I had already checked all the fuses so I figured that it had to be the relay.

I took a gamble on that and bought a new one for $129.99 (ouch - especially for such a small part). The gamble was that O'Reilly's don't exchange electrical parts after you buy them. But I replaced it and my problem is now solved.

Compressor relay location

Could someone tell me the location of the compressor relay on a 97 ford expedition?

If you look under the front passenger side wheel arch towards the headlight, there is a cavity. The headlight is on the front part of the cavity and on the back part you will see a small batwing shaped device with a finned heatsink. That is the relay. It is held on by two small nuts and has a 4 pin connector.

eohalloran said:

The rear end on my 1999 Expedition has gone down for the second time in 2 years. Last time I had this fixed it cost me $1300

Click to expand...

i paid $200 out the door for my coil spring conversion F&@# that air suspension and do yourself a favor and just spring the SOB

Hello "eohalloran" I was wondering if you could tell me where that relay is located that you paid 129.99 for?

I'm having all the same problems you were having but my truck is a 2002 Expedition (Eddie Bauer Edition). I figured I'd start changing all the small cheaper parts first I guess.

Thanks

eohalloran said:

... I figured that it had to be the relay.
I took a gamble on that and bought a new one ... I replaced it and my problem is now solved.

Click to expand...

I have had the same experience with the compressor on my '01. It runs with the relay bypassed. Very cold weather lately (single digits-20's) may be taxing this tired compressor. I am unaware of any air leaks.

How long did the replacement relay last for you?

I found one relatively cheap and am giving it a shot:
Amazon.com: Standard Motor Products RY319 Relay: Automotive

Putting off the inevitable conversion of this air ride for now.

as you all seem to do your own repairs I would suggest that you get a copy of,

Ford workshop manual on DVD. Can be obtained from seller "morpheousking" on e-bay. Cost about $10.00 Much better than Clymer, Haynes or Chilton and also includes wiring diagrams

Don't waste your money on a Clymer, Haynes or Chilton Manual.
It is well worth the $10.00 just make sure you get the DVD for your year as the seller has different DVD's for different years

Anybody have experience with Standard Motor Products parts?

I'm unconvinced the OEM compressor relay was a great part to begin with. There is a $122+ price difference. We're talking about a relay for cryin' out loud.

I have had great luck with $8 Ebay COP's in the past. Big risk/reward at the price. I think the ease of replacement of the compressor relay makes the gamble on the SMP RY319 equally worthwhile, especially if I have unknown compressor (or systemic) issues that could fry the more expensive OEM part. If the cheap relay lasts until warm weather arrives when I can better inspect and evaluate the air ride suspension I will be happy.

I'll follow up with results.

Replaced relay with SMP #RY319. The compressor runs and the system has held air for longer than 36 hours. If the air ride suspension fails again I will do the conversion.

I found conflicting information on the OEM relay. When I searched initially, I found OEM part for 2001 Expedition listed as F3LZ-2C013-B. This I cross referenced with RY319. When I took the factory part off the truck, the number printed on the relay read F3LB-2C013-AA. I did not have this information when I ordered the SMP relay. If I had the part number from the original relay I would have been tempted to try a used one from Ebay.

Anyway, it seems all three relays are appropriate for this application. So far so good on my repair. I hope this information is helpful to somebody.