HVAC - 410A Refrigerant In General Repairs

If the unit has no gauge glass or other means of level detection for the receiver, you may be relying on the liquid line sight glass. If the system charge is too low, there will be bubbles, and you can tell you have added enough liquid when the bubbles stop.

However, a plugged filter/dryer (or other restiction) can create the same symptom, and it may be hard to differentiate. If bubbles persist from these other causes, you might add too much liquid. If it backs up into the condenser, the discharge pressure will rise noticeably. Evacuating and recharging from scratch to the correct weight is precise, but time-consuming.

With the zeotropic blends like 410A, added refrigerant must be in liquid form (inverted canister or 2-valve cylinder).

Yes I understand what you are saying but is there any long term damage done to a 410A system that has lost some of its charge and all that is done during the repair is the charge added to the precise amount needed without a completely reclaiming, vacuum and etc.?

I have heard that zeotropic blends leak out at a different rates which can cause the balance of the refrigerant to be off enough that in the long term could cause early failure to the equipment.

I guess I am looking for proof, if there is any, that backs me up when I explain to the customer that taking the short way out doing the repair will cost more in the long run.

Good point. If the leak was liquid, the remaining composition shouldn't change, and simple replenishment would be okay. But if the leak was vapor, it was probably fractionated, and the remainder would no longer be correctly proportioned.

Evacuation/recharge avoids that problem as well the problem of guessing how much to put in. It costs a bit more, and you should be prepared to explain the reasoning to customer.

Thank you for your answer, we have been telling our customers that we should evacuation/ recharge to do the job correctly. I now know by your answer for sure that if the leak happens in a vapor state it would probably be fractionated.

Thanks for the info it is much appreaciated.

I have heard that zeotropic blends leak out at a different rates Since it is a blend of two refrigerants you can explain the temperature glide concept during boiling and condensation. For a non technical customer it will be very difficult to understand this. You have to explain in simple common terms.

If you have a leak from an R-410A system, does the entire charge have to be replaced, or can the system be topped off?

Since R-410A acts very much like a single component refrigerant, any change in composition due to a leak is minimal. The system can be topped off, without removing the entire charge. There is no practical limit to the number of times a unit can be topped-off or the refrigerant recovered from a unit. However, we do recommend that all leaks be repaired before topping a system off. Excessive superheat is an indication of low charge, and the possibility of a leak in the system should be considered.

http://www.epatest.com/R410A/manual/manual.jsp#s

This should answer your first question. Secondly, with certifications & cost of special tools, it should reduce the number of shadetrees.