MAC5200: safety valve goes off/cut-out pressue does not seem to be working properly. Is there a way I can test/adjust the pressure switch to resolve the problem.

This is an easy fix.. you need an new safety valve or a new switch.

If the safety valve releases pressure before the max pressure replace it.
the switch has a cut in pressure of 120 psi (this means compressor will start when pressure falls to 120 psi.
The cut off pressure is 150 psi. This means the unit will shut off at 150 psi.
You need to watch supply pressure to see if it exceeds 150 psi. If it does replace switch.


Safety Valve Part Number:AB-9415379
Pressure Switch Part Number:AB-9415626

maybe you are reading the gauge wrong
the tank gauge and the regulator gauge will read the same but the gauge that reads when you adjust the regulator is the out line pressure to be n maintained during tool use

Check your Safety Valve. It is on the back of the tank sometimes on one of the pressure switch ports or on the air manifold. It has a ring on it to pull to relieve pressure from the tank. The spring in these can get overheated so they don't hold air unless the tank gets over 165 psi. When the motor is running hold the center pin in to see if you have the same results. If the valve holds air until you let it go, replace it.

Plunger inside the regulator could be stuck or adjustment knob stripped. Let the air out of the tank and take the regulator apart, lube with light grease (no kit available for this reg.). The factory part is expensive so replace (if needed) with generic, careful with size however because there is not much room under the panel and between the gauges . Easy temporary fix. Remove the safety pop valve and install a tee (or check under the pressure switch for spare port) re- install pop valve on the tee fitting. On the second port of tee fitting install a quick connect valve for full pressure. Generic regulator is sold at Lowes that can be installed on the temporary port.

The pressure switch (on / off switch) must be adjusted or has failed. A qualified Bostitch Technician can determine if the switch can be adjusted or must be replaced. Each model is different and without the model number I cannot give you a more precise answer.

where the plug in goes into the pressure switch you can take the cap off and you will see the electrical points and on the inside of the plastic cap it will you show you the two screws to adjust there. one screw will be to raise or lower the min and max pressure equally and the other is to adjust the differential between them. But make sure not to exceed recommended pressure of the compressor or you will blow safety valves, the safety valve will say what pressure it will go off at

Sounds like the unloader valve is not working properly. The unloader typically is at the end of a tube going to the pressure switch. The unloader is tripped when the pressure switch cuts off. The purpose of the unloader is to bleed the pressure from the cylinder when the compressor cuts off so the next time the compressor cuts on it will be starting in an unloaded condition.
when the compressor cuts off you should hear a discharge of air for about 3 to 5 seconds if the switch is working properly. The unloader can be adjusted if necessary by loosening the jam nuts and adjusting the unloader towards the lever on the pressure switch.

do you mean the relief valve. it is factory set for your safety and the sefety of the equiptment. also known as the safety relief valve.

if you are talking about working pressure you need to adjust that with the air regulator.

if you are talking the cut out pressure sensor, again this is also factory set for safety. if your equiptment is designed for 110 psi then when your resivor reaches that set point it should cut the motor off and stop running.

The adjustment for "Cut-In" and "Cut Out" can be found under the pressure switch cover, if available. Some switches are sealed to prevent tampering that might compromise safety.
If you remove the cover you will see the four electrical connections and one or two screws with springs under them. Most times if the adjustments are accessible you will find a set of instructions under the switch cover. One screw will adjust both the "Cut-In/Cut-Out" pressure and one to adjust the "Cut-Out" pressure only.

However you need to remember some important issues regarding these adjustments. The first is that the "Cut-In/Cut-Out" pressure is set at the factory and is set there for a reason. The only reason to change these is because over time the adjustments can change or you are installing a new switch. The other thing to remember is that the safety relief valve is set just above the "Cut-Out" psi. So any meaningful increase will only trigger the safety valve.

If you need to readjust your compressor back to factory settings make sure you do it with small adjustments. 1/4 to 1/2 turn of the screws. Run the compressor and check both the "Cut-In" and "Cut Out" psi setting before making another adjustment.

Hope this helps, good luck and please be careful.

Your power cord should go into a plastic box (the pressure switch). Your on/off switch is probably on the same box. Unplug the unit, remove the cover of the switch, and you will find one or two adjusting screws. The main adjustment is usually a silver or gold screw (NOT the terminals with the wires on them).
Turn clockwise to increase pressure, counterclockwise to decrease pressure.
If the differential (the difference between cut-in and cut-out) needs adjusted, there is sometimes a second (usually plastic) adjusting screw behind and to the left of the main screw to adjust the cut-in without adjusting the cut-out.
You won't get the differential any tighter than maybe 25-30 PSI.
Test run while bleeding off a little air, and see if further adjustment is necessary. If so, you can adjust with the power plugged in IF YOU ARE CAREFUL - the wire terminals in the pressure switch are exposed and they will have voltage that can zap you.
Make sure you don't overpressurize (run higher than rated pressure) the unit, or your motor will overload, or the safety valve will pop off.
Let me know if this helps!