Scroll compressor free#

Is that what is going in here? Maybe, but if so, it's only part of the story. Do certain fusite terminals short out more easily than others? I'm sure some are more susceptible than others. There are scroll compressors that use them there are reciprocating compressors that use them, the ice cream truck that plays that obnoxious music driving through your neighborhood probably has one-on the refrigeration compressor. There are many different types and designs of Fusite terminal, just as there are many different types and designs of compressors. So, when we say “fusite,” we are using a ubiquitous term for a sealed glass to metal compressor terminal feed through. All of the literature mentions arcing, and I spoke to more than one tech rep who mentioned the “fusite” plug arcing or being damaged.įirst, Fusite is a brand name and one of the companies in the Emerson family.

It will overheat and fail to lubricate properly, but that isn't the only reason or even the primary reason. The totally obvious reason is that the compressor itself isn't designed to run in a vacuum. That is a bad idea on any compressor, but it's even worse on a scroll. In addition to that, there are lots of threats and warnings about running a scroll while it is in a vacuum, as in if you had just evacuated the system and then accidentally turned the system on. There is an audible increase in sound when the scrolls start unloading.” This is to prevent the compressor from pulling down into a vacuum. Either they are equipped with a low-pressure cut-out or some sort of low-pressure/low compression bypass like the one shown in this USPTO drawing.įor example, Copeland AE4-1303 states: “Copeland Scroll compressors incorporate internal low vacuum protection and will stop pumping (unload) when the pressure ratio exceeds approximately 10:1. Add in some extra nastiness, and you are at risk.įirst, many scroll compressors won't even allow you to pump them down into a vacuum.

Scroll compressor free#

Free metallic particles due to copper leaching (acids), small metal pieces left from copper fabrication, or metal from compressor breakdown due to other issues such as overheating, flooding, and improper lubricationĪll of this to point out that tolerances are tight in a scroll, to begin with.Some of the factors that can decrease resistance further and lead to problems are: Another thing to consider is the scroll will read lower ohms to ground when it is cold than when it is running due to higher refrigerant/oil density at a lower temperature, and, of course, you are generally doing a meg test when a scroll has been off, so that makes it tricky. Besides the fact that this makes a scroll difficult to successfully meg (essentially impossible with a tool like the Supco M500 because it only reads down to 20 Mohms), it is a clear indication that a scroll compressor is running tighter resistance tolerances and a higher risk of internal arcing due to many factors. Copeland states in bulletin AE4-1294 that megohm readings as low as 0.5 megohms to ground are acceptable. The motor's location at the bottom is the biggest thing. That results in closer tolerances/distances between the electrical components and the other metal parts. A scroll has a more compact and balanced design, as there is no need for “suspension” as in a reciprocating compressor.When the compressor has been off and is cold, there can even be some liquid refrigerant in the compressor. In a scroll, the motor is located on the bottom, which means that the motor is immersed in refrigerant and oil.There are many differences between a scroll and a reciprocating compressor, but let's focus on the few that are pertinent to this conversation (or at least the pertinent ones I can think of). These points have been confirmed with Copeland (Emerson) as being on the naughty list this Christmas.Ī scroll is like any other compressor in that it has a motor and a compression chamber “hermetically” sealed inside the shell. Don't do any megohmmeter test with a scroll under vacuum.

Don't run a high voltage megohmmeter or Hi-pot test on a scroll (As a general rule, don't go over double the rated running volts).

Don't pump down a scroll into a vacuum.

This tip will be like an episode of Columbo we will start with the what and who and then get to the why.