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Jun Air Condor MDR 21-EA-11 has bad connection

Published Categorized as Air Compressor Pressure Switch Guides, Air Compressor Wiring Issues, Jun Air No Comments on Jun Air Condor MDR 21-EA-11 has bad connection

by Sam
(New York

I have a JUN-AIR compressor with a Condor MDR 21-EA/11 pressure switch. The pressure switch appears to have a bad connection: when pressure builds up in the switch, part of the moving switch gets pushed away from where it should be.

Condor MDR 21

When the switch gets thrown back and forth, the electrical connection is lost and the pump does not get power to run again. Occasionally, the switch will start smoking (Note char marks on box).

The loose connection is clearly visible sticking out of the side (see picture). I have another Condor switch of exactly the same model (but broken in its own way) and the connection is not falling out.

I looked for some screw or something to open up the guts of the pressure switch, but it appears to be completely solid. If I hold the loose connection just right, the switch goes on and off perfectly. But I use the pump sometimes continuously for days on end and I am uneasy about leaving the pump unattended with a bad connection. I am tempted to fix the switch with just a piece of tape to keep the connection from falling out.

What do you suggest? Do you have (or can you find) a schematic of the internal parts of the switch? I don’t mind trying to fix it myself, but I can’t see what’s going on inside.
Do you know of a congenital problem with this switch? (As I said, it’s not the first Condor switch to die on me…)
Can I replace the switch with a different model/brand? Can I just match specs for ports and pressure cut-in/cut-out?

If I do need to replace with same kind of switch, do I need to replace the unloader valve as well? I don’t think the valve is broken (tank hisses for just a split second).

Many Thanks,


Sam, for the typical cost of a new compressor pressure switch, I recommend that you don’t try to fix yours, install a new one.

No, it doesn’t have to be the same brand, although the Condor MD11 is a well reputed switch, as long as the cut in and cut out pressures on the new switch are close to your present switch settings, and if the switch on your present compressor operates the unloader valve you will want to ensure that the unloader valve will function properly with the new switch.

Sometimes, it’s easier just to replace the old with the same make. If that is the case for you, contact Jun Air to locate your local distributor.


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By Bill Wade

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