![]() ![]() ![]() According to him, modern R134a unit no longer uses PAG oil (they use POE instead). Star882 have commented that this may be related to the use of PAG oil. However, what I've heard from some engineers it that, when using R134a, bubbles may continue to appear in the sight glass despite the system has the adequate amount of refrigerant what may lead to refrigerant overcharging event. Regarding the bubbles that I mentioned previously, I meant that you should add refrigerant until you stop seeing bubbles in the sight glass. We're not going to raise the SC and SH every time you have replaced system components or servicing. Once you have refined the refrigerant charge, maintenance procedures are based on the charge weight. Despite it's the most accurate way, raising the SC and SH is a procedure only valid for refinement of the refrigerant charge calculation used in the development of the system. Why do you see bubbles in the sight glass? What are these bubbles in fact?Ĭorrect me if I'm wrong. I disagree, measuring SC and SH is the most accurate way. PAG is not really used much anymore for refrigeration, since it absorbs moisture even easier than POE. Modern R134a units use Ester (POE) oil, not PAG. High-side system pressure below 240 psi (1640 kPa):p>:pSummarizing: R-134a is very hard to adjust the recharge rate to so it's usually weighed into the system rather than depending on the sight glass method.:p:p High-side system pressure below 240 psi (1640 kPa)=1500 rpm).(It's normal for some bubbles to appear in the sight glass of R134a systems in low fan speed). The "sight glass charge inspection" can be used if the following conditions are met : The result is that the sight glass looks slightly cloudy even if the system is fully charged, except at very cool outside temperatures". ![]() PAG oil does not fully emulsify the way the mineral oil used with R12 would in the past. It uses a different type of oil, polyalkaline glycol (PAG). However, this is not applicable for R-134a. I've googled the subject and most of the technical articles have mentioned that in the days of R-12 refrigerant, the sight glass on top of the receiver-dryer would look clear when the system was right, indicating liquid refrigerant with no vapor bubbles. The weight of the complete refrigerant charge is the most accurate way to charge the system. ![]()
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