Midmark® Smart G-Vacuum Float Assembly Test and Repair
The switch has contacts that remain open until the liquid in the separator rises, causing the float to rise until the magnet contacts the switch.
When the magnet contacts the switch, the open contacts inside the switch close.
When the top float switch closes, the vacuum pump stops running until the bottom float opens and the cycle starts again.
The upper and lower floats interact as a latching circuit with the internal relay to release upon drain below the bottom float. The magnet in the float is to activate the switch within the stem.
Running pump with float wire connection removed from base other than to briefly troubleshoot can cause damage to the pump.
When working on Twin units, unplug parallel harness.
To check float switches
1.Turn power off at on/off switch and main power supply box.
2.Remove gasket on separator lid.
3.Lift lid/float assembly out of tank and lay across top of tank, put floats in down position.
4.Remove electrical panel cover.
5.Turn supply power and unit ON.
6.Set meter to Ω.
7.Lift bottom float to closed position. Measure resistance from Common to Bottom, Present, and Top at J6 on PC board. Repeat for the top float.
8.With both floats closed, lower the top float to the down position, then the bottom float. The motor should not start until the bottom float is down.
Verify readings are within range. If not, check float harness continuity.
| Check | Meter Reading | Required Action |
|---|---|---|
| With float up | < 5 ohms | Ok |
| With float down | OL |
Ok |
| Float up or down | Out of range | Check float harness continuity |
To check float harness
1.Turn power off and unplug float harness.
2.Lift lid/float assembly out of tank and lay across top of tank.
3.Move floats to down position.
4.Set meter to Ω. Probe end of float harness, each pin 1, 2, and 3 to pin 4.
5.Lift float to closed position.
6.Measure at the harness between pin 4 and the pin of the raised float. Verify readings are within range. If not, replace float assembly.
Motor should stop after top float switch is raised.
| Check | Meter Reading | Required Action |
|---|---|---|
| With float in closed position | < 5 ohms | Ok |
| With float in down position | OL |
Ok |
| Float up or down | Out of range | Replace float harness |
