Low oil level in the refrigerant

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Low oil level in the refrigerant

Postby Charles5654 » Sun Oct 18, 2020 5:50 pm

On my 2002 Civic SI R134 refrigerant was added in two occasions:
- The first time the leak could not be found. Refrigerant was added, but I don’t know the quantity. Oil was not added
- The second time it was determined that the evaporator was leaking and it was replaced. I don’t know if oil was added to the new refrigerant. The bill does not list any oil

Today I have used the ENVIRO-SAFE Pittstop R134A Oil Checker to try to figure out if I have enough oil in the refrigerant. According to the Pittstop Checker the oil level is very low and the A/C should not be used before adding more oil. I have been using the car a few weeks after the evaporator was replaced and I am of course very concerned about my compressor locking up and contaminating with debris the all A/C system.
Could somebody make a recommendation about how to proceed?
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Re: Low oil level in the refrigerant

Postby Al9 » Mon Oct 19, 2020 3:13 am

Don't know how this test works, but it likely checks for how much oil is circulating together with the refrigerant, and a low oil circulation rate can also be caused by a lower than normal refrigerant charge.

That said, having a FSM at hand would be the best option, but anyway Denso states (here) that a reference value of 20% the system oil charge normally resides inside the evaporator. For a 5 fl oz system oil charge, that's 1 fl oz. So a sound reasoning would be to add that 20% back (in addition to any amount that was recovered together with the refrigerant) when changing an evaporator only. And that's what likely applies only for a leak-free evaporator and a correctly charged system.
Once a leak develops, things get more wild guess than sound reasoning, some say 1 oz, others 2 oz to be sure, it gets nothing but a wild guess. Especially a leaking evaporator, a part that is able to store and then leak a huge amount of oil. The best option would be to flush the entire system and add the whole system oil charge back inside the compressor, but it has to be done carefully so to not leave any residual flush agent inside (evaporative flush solvents are the best option), and it can get time consuming, especially when the expansion device can't be effortlessy removed from the firewall/from a line thereby exposing the evaporator's piping/flange (as with my car). That's what i'd recommend you to do, or have someone competent enough do.

In my own experience, shops rarely go that deep when doing AC repairs, unless explicitly instructed/almost "babyed" by the customer into doing things the right way (i had one fit a new compressor to my car, and had i not provided them a hollowed out second hand TXV that fit on my evaporator, they would have been unable to flush, lacking the necessary adapter/s in their flush kit; had i not provided them the right oil, they would have used the wrong one; had i not instructed them to fill the new compressor with oil through the drain hole as required by the OEM manufacturer, they would have filled it from the suction port).
They just want to cut corners whenever possible.
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Re: Low oil level in the refrigerant

Postby Charles5654 » Mon Oct 19, 2020 10:22 am

As you stated, the Pittstop r134a Oil Checker checks for for how much oil is circulating together with the refrigerant (some general information on this product is available on Amazon.com)
Many thanks for the excellent information and advice that you provided in your post. Because of the age of the compressor and because there is a good chance that it has been used with insufficient oil for quite some time, I am considering replacing the compressor as well.

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