R22 comp was running R417a now filled with R404

[Ronjon]

Hi guys and gals hope you can give a bit of advice

Just a quickie.

Have a custom split air con system which had a compressor stamped for R22 which I know for a fact was filled with and running on R417a out of the factory(No problem there then) until it crapped out while they were in the arse end of nowhere.

It was then vacuumed out and refilled with R404 (It was all they had at the time) which it is currently running on reasonably well now. Any ideas how much trouble we are going to be having in the future with this scenario? No oils or system components were changed just a quick pump out and refill.

Any insight would be great, forewarned is forearmed and all that.

Many thanks

Joe

[nike123]

Compressor doesn't care what refrigerant it is pumping.
His only consideration is right oil. If it is in factory charged wit r417a and POE oil and than changed to R404a than everything is OK regarding used gas. But you could have problem because of inadequate capillary length and therefore excessive or insufficient superheat which lead to problems with capacity and possible overheating or liquid in compressor.
If it is mineral oil inside, than you have serious trouble with R404A.

[Ronjon]

So with all that in mind seeing as it would have been bought as an R22 compressor and filled with the drop in replacement gas R417a I am guessing they wouldn't have bothered doing anything to change the oil the compressor would have been filled with from the factory.

Basically forgetting about it ever being filled with R417a would the oil it would have been supplied with for pumping R22 be suitable for use with R404?

We are getting liquid or extremely wet gas back to the compressor as the casing is sweating, is there anything non invasive that can be done to prevent that like reducing the charge a bit?

[Ronjon]

Forgot to ask what happens if it is the wrong oil, what is the eventual result?

[nike123]

Basically forgetting about it ever being filled with R417a would the oil it would have been supplied with for pumping R22 be suitable for use with R404?

Nope!


We are getting liquid or extremely wet gas back to the compressor as the casing is sweating, is there anything non invasive that can be done to prevent that like reducing the charge a bit?That is explained here:


But you could have problem because of inadequate capillary length and therefore excessive or insufficient superheat which lead to problems with capacity and possible overheating or liquid in compressor.

You need skilled service technician to resolve that issue. I would charge it with original amount of R417A.

[nike123]

Forgot to ask what happens if it is the wrong oil, what is the eventual result?
No return of oil in compressor and eventually dead compressor.

[Ronjon]

Well many thanks for all that, my only refrigeration experience is with ammonia systems so capilarys and tiny tin can compressors are a black science to me, I like it big and smelly, dirty great 3.3kv compressors with names like howden and 440v Grasso, huge flash vessels and surge drums, big clanky old pumps, expansion valves you can barely lift.

Trouble is this system is out of my control but what i can do is go back to them and let them know we are heading for a whole heap of trouble, I know liquid back to a comp is bad news, lack of superheat etc... but was wondering what the eventual symptoms would be.

I would be interested to know what happens if the wrong oil is used as in my case, does the oil migrate, become acidic, become denser or thinner, lose its lubricating properties, carbonise, disentigrate etc...

With what has been done on here will the system be alright after simply being pumped out and refilled with the correct amount of R417a? or will more need to be done? if so then what?

[hyperion]

If, as has been presumed, the compressor was originally made for R22, then it most probably will have been filled with mineral oil. Changing to R417A is a normal routine and does not always require an oil change.
However, as far as I am aware, R404A requires POE oil as it is not miscible with mineral oil. Eventually oil mist will be pumped over and dropped out somewhere in the circuit, probably in the evaporator.
As R404A is not miscible with the mineral oil, the oil will collect or pool, thee will possibly be reduced cooling performance and eventually the system will starve the compressor of oil with the end result being a seized compressor.
This problem may be agravated by the fact that you mention the potential of liquid getting back to the compressor and further diluting the oil.
Reclaim the R404A as soon as possible and charge with the correct amount of R417A or R22R.
Be aware that during the reclaim process you might also end up removing some of the oil.