Hobbs Switch Adjustable?

[chimpvalet]

Hello,

I've a Hobbs M-4009 15, AKA Stewart Warner 76062 more recently, and it lists as N/C with opening fixed at 15psi. There is what appears to be an adjuster screw with locking nut dab marked with red Loctite on the top of its case. Anyone know whether the set point might be adjusted lower?

Steve

[jsgarage]

I adjusted one for an '80s Ford A/C. You'll have to kluge a tee fitting up to apply pressure with a gauge, to see what the effect is, turning the screw either way. Do not expect it to be linear- 1/8 turn might vary 1 lb while 1/2 turn might be 4 lbs.

[chimpvalet]

Hey thanks! It figures the thing could be adjusted, given the screw/nut mentioned. That it would be non-linear is understood.

Cheers

[bill jones]

---here's my story about adjustable pressure sender units from some years ago

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