Where is the electrical switch for the tag axle air compressor? Is it a pressure switch on the high side of the two pneumatic controls on the dash? Thanks

On my 78 the switch is the Knob with the bleeder valve in the centre. Rotate the knob till it pops out and the compresser will start. Watch the appropriate guage till the pressure is where you want it and then push the Knob and rotate to lock it. If the pressure is to high the press the bleeder valve in the centre of the Knob. That's how mine works.

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On my '90 Regal SE, the only switch I've found is a pressure switch mounted on top of the comprerssor itself. If there's a manual control, I haven't found it. The pressure switch maintained the air bags at 40 lbs., more pressure than the manual recommends, but what seems to work best.

The compressor failed last year, and I jury-rigged a $15 Harbor Freight compressor. If I carry less than 40 lbs., on the tag, there's a noticeable difference in handling, despite having Firestone Ride-Rites on the drive axle.

Thanks for your info. The problem with mine is one of the valves is stuck on and the compressor run's constantly. I will probably connect a temporary switch.

Mine ran constantly too, but it was the compresor itself that failed, not a check valve.

There is no switch on either of my gauge/valve panels. The pump comes on whenever the pressure at the pump drops below the pressure switch setting. When the knob is pulled out, the pressure switch then reads bag pressure, and if bag pressure is lower than the pressure switch set point, the pump runs. The pressure switch is mounted on top of or next to the pump, reading the pump output.

Roy, mine also likes 40 to 45 lbs. On yours, where does the power on yours come from? Ign, chassis batt or house batt?

Bill, I've never traced it to the source, but it must come through the ignition, it only runs when the ignition is on. Furtherrmore, it pumps up both sides equally. I haven't found a way to vary the pressure side-to-side, though I have separate dash switches & pressure gauges.

The gnomes at the Barth factory sure found a lot of different ways to wire and plumb these rigs.

I would be concerned about the ignition switch carrying the current of a 10 or 15 amp pump. Maybe a relay would be better. My pump was hors de combat when I bought the coach, and the wire had been lost to the dark mists of history. I bought a 10 amp Thomas compressor and wired it from the battery via a momentary switch. I can vary it side to side depending on which valve is opened. There is one line leaving the compressor, then the air tees off with a line going to each valve, which controls each bag. My bags leak down slowly, so will probably need new ones.

Anybody got numbers or sources for new ones? I don't mind airing them up every day, but would really be unhappy with one failing far from home.

I found an add on fuse panel that is after ignition switch. There is a number of things connected to it one being the air compressor.
I would think there is a relay for that buss.
I'll try to find out. There is also a relay on the bracket above the alternator. Not sure what it powers yet. I ran my pump to one of the spare switches on the dash. Now I can turn it on when I need it and not have it running constantly.

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Originally posted by shtym:
There is also a relay on the bracket above the alternator. Not sure what it powers yet.

If the relay you mention is cylindrical with two heavy terminals and one or two smaller ones, it is most likely a start relay.

It's not a start relay. The wire's are too small mabey #10 or 8. I have to go to work for a few days when I get back I'l dig in and check it out.