Midmark® Smart Air Compressor Pressure Switch Test and Repair
During the Compression Cycle
When the storage tank is filled to the preset pressure the pressure switch will open and stop the compressor.
During the Purge Cycle
The pressure switch shuts off current to the compressor head(s) and the solenoid / purge valve. A mechanical valve on the pressure switch opens up to unload the compressor headlines. At the same time the solenoid opens, starting the purge cycle.
Cut-In / Cut-Out time
Cut-In / Cut-Out is the minimum and maximum discharge pressures at which the compressor will switch from unload to load operation (cut-in) or from load to unload (cut-out). The pressure switch controls Cut-In / Cut-Out times.
Pressure Switch Testing
Serial Number Range: V2200 thru Present
|
Model |
P21-050 | P22-050 | P32-050 | P52-050 | P72-050 |
| Serial Number | V2200 thru Present | V2200 thru Present | V2200 thru Present | V2200 thru Present | V2200 thru Present |
High Voltage. When testing components with power on, use care to prevent electrical shock.
1.Perform Adjustment. Refer to: Pressure Switch Adjustment
2.Turn Power off.
3.Remove pressure switch cover and verify there are no black/burnt melted wires. If there are, replace pressure switch. Refer to: Pressure Switch Cover
4.Turn Power On.
5.Set meter to VAC.
6.Bleed tank pressure down to less than 80 PSI. Pressure switch will make an audible click.
a.Check line voltage across L1 and L2.
b.Check line voltage across T1 and T2.
c.These voltages should be the same.
|
Meter Reading |
Status |
Required Action |
|---|---|---|
|
T1 / T2 = No Line Voltage |
|
Replace Pressure Switch. |
|
T1 / T2 = Line Voltage |
|
Pressure Switch OK. |
