A AC unit. The system’s fault may cause radical changes to the pressure figures indicated by the micron gauge. A root cause could lie in the YouTube video “HVAC Vacuum Issues: 5 tips for Monitor a Micron Gauge reading that’s jumping around!”
Water in the system is the main cause for fluctuations in the micron gauge of pressure. Water that enters the system at the point of exit of the vacuum pump could be drawn out leading to a sharp diminution in the pressure reading. Similar to this, the oil contained in the evaporator’s coil may trigger sudden changes in pressure. As it moves along both sides of the coil, oil can block space and cause tension fluctuations within the gauge of microns. An engineer should carry out an oil blowout procedure to solve the issue.
A dirty gauge for vacuum using oil may also trigger rapid pressure changes. This issue can be resolved through cleaning the gauge using alcohol. Pressure gauge issues with microns can be the result of intermittent leakage around the valves’ surfaces or pipes.