Air Compressor Power Issue

[freedombro]

Over the winter the rear suspension air compressor on my '86 345 stopped working. I typically start the rig and inflate the airbags once or twice a month when in storage. The motor isn't getting power. I show 12v to the air pressure switch, but get nothing when I jump the switch and go direct to the compressor. I applied external 12v power to the motor and it fired right up. My multimeter shows nearly 12v on the line I jumped to the compressor. I made sure it was grounded properly...nothing. I'm a novice where 12v power is involved. Any suggestions would be greatly appreciated? Thanks for your time!

[Magnet18]

They ran a really long skinny wire from the battery to the dash back to the compressor, the wire isn't thick enough and is failing, my 310 unit had a similar failure

Mine is now powered by a toggle switch in the battery compartment, you can also try re-running heavier gauge wire to the dash/adding a relay

[mayco]

A good deal of folks here have rewired their compressor when they install a replacement.
A common way to do that is to run a fairly heavy wire (#8 or 6) from your battery to the compressor compartment with an inline fuse. Use your existing OEM wire as a trigger or switch wire with both feeding a combination relay/pressure switch like this one. https://www.amazon.com/VIAIR-90110-P.../dp/B000FQ1HM4
It will give some flexibility on the size and amp draw when choosing a new compressor. Pretty easy job once you get into it. Thos relays are well marked as to which wire goes where. Good luck.

[Isuzusweet]

+1 on the heavier gauge wire direct to the compressor, and using the existing 20 amp wire as a solenoid trigger.
My ARB twin cylinder compressor came with an internal pressure switch that you power with the wire from the dashboard fuse block.
I also mounted the compressor much closer to my batteries, so the less wire, the better.

Cheers
Sidekick Tony

[freedombro]

Thanks to all for your input.

The culprit was a failed spade connector in the front fusebox. It appears a PO had run a heavier wire from a toggle switch on the dash (I always wondered why?) It currently goes direct to a small aftermarket (85-105) pressure switch. (small round in center left of picture below) I don't see any connection between a relay or solenoid before the pressure switch? The power out of the pressure switch does split and and one leg goes to what looks like a solenoid while the other leg feeds direct into the compressor. Nothing leaves that solenoid. Should that concern me? Here's a pic. Seems like there are several old switches/relays/solenoids not being used. https://drive.google.com/open?id=1D4...kY4_D35JSg11Po

Of course, once I got the compressor working the front air conditioner immediately quit. It's Classic Airstream Whack-A-Mole, as usual.

Thx Again!!

-ko

[mayco]

It looks a bit complicated but if it works...muy bueno! The compressor looks like it's been upgraded. I'm not sure I get adding a switch at the dash for the compressor. It already operates off the ignition switch, or did from the factory. You could probably clean it up a bit but if it's working for you..."if it ain't broke...."