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Question DetailsAsked on 6/20/2014

I just had my outdoor condenser unit replaced with 410a. The condenser had r22. Do the lines HAVE to be flushed?

We had our furnace and coil replaced 4 years ago but not the condenser unit. We had that replaced on Saturday and it's not working properly. I'm meeting with the manager this afternoon. Is the line supposed to be flushed when changing over or is vacuuming enough?

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4 Answers


I have been told that the coil in the split system must also be replaced and copper lines replaced or flushed. Did your installer do those things or not? If not, waht was his reason?

Source: Experience

Answered 5 years ago by PoppyRoss


Response to Poppy, there is a debate on numerous forums on both sides each of which are pretty adamant that they're right. It sounds more of a peeing contest. I have yet to see an answer that sounds convincing on either side. One side says R-11 or other flushing materials are actually harmly. Others say they are essential.

Source: My opinion

Answered 5 years ago by BuddysDad


We have been installing R410a replacement systems since 1997, when carrier introduced them. There is no need to flush the linesets,nor will the flush cause harm,if used properly.

Purging the lineset with nitrogen ,to remove any excess mineral oil is advised. Then of course proper install and vacuum,etc..

You will find your issue is something else,


Answered 5 years ago by BayAreaAC


As other comment said - getting the old lubricant (which was with the R22) out of the system is important - especially as it can pool in the low parts of the system, and it is NOT compatiblewith most new gas lubricants, so ithas to be removed. Vacuuming will NOT remove it - needs to be blown out. As - was it BayAreaAC - said, can be done with the "cleaning liquid" or by blowing out with compressed nitrogen, but you do not want to just leave it in there.

I have seen some very gunky messed because of old and new gases being mixed without cleaning out the old oil - can turn to a gel that plugs the system and does not properly lubricate the compressor.

My recommendation - have it fllushed with the cleaner specified by the manufacturer - not only to get the old lubricant out, but also because without proof of that flushing itemized on the invoice you warranties on the entire system are probably useless. SOOO many contractors fail to adhere to manufacturer requirements for installation (roofs, appliances, HVACequipment, etc), saying it is just not necessary - and void your warranty for you in the process. I recommend not cutting corners.

Answered 5 years ago by LCD

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