Running R404a with mineral oil.

[Brettox]

Help Please! I don’t have an oil test kit at the moment. Is there an ester oil that looks like mineral oil? A long story short! I have just checked through some refrigeration machinery after a major service. Checking the oil sight glasses of all R404a low temp systems the oil is clear yellow like mineral oil. What problems will occur with running R404a and mineral oil?

[old gas bottle]

all sorts of things "maybe"waxing up in expansion devices,blocking of filters,oil problems etc, or just maybe none !,early systems i have seen used mineral oil with little or no problems.by the sounds of it you have got what you have got.if its running ok why worry,if its giving problems pull it out and change it,but if its a old system that can bring other related problems.

[Brettox]

Thanks for the reply. It is a 5year old system previously running on ester oil. the so called ref tecs while doing the service put mineral into all the units. I need advice as to what is the best way forward and what I should inform my customer.

[D.D.KORANNE]

Mineral oil does not get mixed with r-404a

[monkey spanners]

Does the liquid line sight glass go milky every now and then? (might not if the system has an oil seperator) this can be a sign of too much mineral oil in a hfc system.

I got called to a site where the customer had bought a second hand cold room, compressor was an old R22 unit but the system was mow running on R404A! it ran for a few weeks or a month till it snapped a conrod due to a lack of oil return, so if there is any doubt as to what oil they put in your system, i'd change it just to be safe, cheaper than a new compressor

Jon

[lowcool]

if in doubt throw it out

[Magoo]

R -404A and mineral oil will result in chemical reaction and system failure, nothing surer.

[old gas bottle]

well if it had ester oil in to start with it needs comming out asap.why would they have done that .

what i was getting at was when R404A was first put in service was ester oil available ? i seem to remember not, so mineral oil may have been used for a short period.but then again i,am not exactly sure.maybe someone here knows.i can only speak of what i have encountered.