Used refrigerant manifolds

[FronteraRepairs]

A friend offered me a manifold but the high red colored side is not exactly calibrated. It shows like 10 or 20 PSI. The Blue low pressure guage is right on the money "0".
 

My question being, for typical residential fridge repair and maybe small window A/C, is the high side going to screw me up? Or am I going to depend mostly on the low side for accuracy?
thanks

[Koi Guy]

I can't common on ALL manifolds, but most will have a calibration adjustment. Remove the cover lens and use a screwdriver to dial in the gauge. The rubber seals on the ends of the hoses can be replaced if worn.

Not often I use high side, but sometimes it is necessary, especially when there is a possible partial restriction.

[FronteraRepairs]

Thanks for the heads up. I'll keep an eye out fo that adjustment screw!

[abaesemann]

You should calibrate them by a known refrigerant pressure and temperature, not just by atmospheric pressure.

[AccApp]

You can buy new gauges from a supplier like Johnstone for around $25.00 each.The more correct information you have will always help you make better decisions and assessments of a unit's condition. What refrigerants do you plan to be working with? I have a manifold gauge set dedicated to r134a, one for 410a and another for R22 and the odd 414a/b (R12 replacements) job i do.