fluctuating high and low pressures.

[hvacstudent1234]

So I'm a 2nd quarter HVAC student and am working on a Evaporator plated belt driven system (a boxed version of those used in Schwan trucks). It was leaking so I recovered and evacuated the system. Charged it, but now both the high and low pressures are fluctuating like crazy. Was thinking i may have accidently overcharged the system. Any suggestions?

[VTP99]

Non condensables
What was your micron number ?

[hvacstudent1234]

It hit 500, and did rise up. But not by much..

[VTP99]

Did you purge your hoses when charging ?

[hvacstudent1234]

Looking back on it. I don't believe I did. (oops) Was in a hurry to get it charged, honestly. Would that introduce condensables into the system even when in a vacuum?

[Out in the cold]

You should always purge all hoses not evacuated but I doubt that amount would cause any extreme fluctuation. I haven't worked on any Schwans units but many other transport units. Most of those units have a charge plate telling you how much it holds, did you weigh it in? We need more info, what are your pressures? Is compressor tripping on a safety and shutting off? What refrigerant?

[TechmanTerry]

You had a leak? You fixed a leak? You have a SGMI? You got press/temp to go w/ that "fluctuating" press? Got a freon # to go w/ that? Got high head press to go w/ that "overcharge"? Jus sayin.