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How to add oil to OTR?
Looks like it is time to top off my OTR with freon (134a) again. Still cooling but just barely. Last time done in 2017. Obviously, there is a small leak but I’m ok with having to top off every three years.
Now my question: Oil level at compressor seems at the low mark. Is there a simple way to add POE oil to the OTR while recharging? Would like to avoid vacuuming down the entire system.
Gerald
Edited to indicate that OTR requires POE oil, not PAG oil.
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8 Replies
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I’ve seen it sold in little 4 oz pressurized cans and installs like installing a 12 oz can of freon.
But maybe it comes in a larger size??
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Oil injector for AC systems, on Amazon.
https://www.amazon.com/gp/product/B01N95O7UZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
I have one similiar to what David posted. Got it at NAPA years ago. Haven’t used on bus but worked great for adding oil to auto R12 systems that I could only find non-pressurized in quart bottles.
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I was not aware of the little hand-cranked oil injectors. It will take a few fills but it should do it. Thanks for all the responses.
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I just looked up the Carrier 05G approved oils for R-134a. They all seem to be POE oils (Castrol Icematic SW-68C, Mobil Arctic EAL68, Emkarate RL68H), not PAG oils.
I double checked in the Prevost maintenance manual. POE oil is required, either Castrol SW68 or Mobil Arctic 1.
So. our OTR requires POE oils not PAG oils (in case someone reads this in the future).
Gerald
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I am in this boat right now. I need to add some POE oil and I came across a thread with the Carrier manual for the compressor. If you look on the left side of the compressor (as viewed facing the front of the bus, so on the port side), there is an angled boss with a plug in it that you can fill the oil from. It did not explain whether you can do this with the system charged though. It appears to be on the bottom side of the pistons, so it would make sense that you could close the service valves to the compressor (for a little added protection from loosing refrigerant) and add it there. Also, it said that POE oil is extremely hygroscopic and to prevent it from coming into contact with air as much as possible. Has anyone added it through the oil fill hole with the system charged?
See item #6 on page 1-2
https://carrierscrewcompressors.com/product-files/05G-models.pdf
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See your Prevost mx manual. In mine its Section 22, 8.1.5 on page 22-23, and 7.4 on page 12-16.
He’s a link to mx manual for 1990-2000 XL: LINKGood Luck -
I think the compressor’s sump will be fully pressurized as the high and low side equalizes after you turn off the compressor. You’d have to pump down the refrigerant into the accumulator before you open up that service port.
The little oil injectors are much easier to use as long as you don’t have quarts to add. There are injectors that use refrigerant to push the oil in, others just screw in to force the oil into the system.
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Thanks for the help. I think I am going to have to pump it down so I can repair the suction side valve at the compressor anyway. It leaks as soon as you start to turn it. I’m afraid if I pump it into the accumulator, I might introduce air through the leak when I reach negative gauge pressure on the low side. I have been thinking about purchasing a Robinair recovery machine to fix this and maintain my and my family’s passenger cars. I already have a vacuum.
As a result of the leaking suction valve, I can only measure the high-side pressure, and it is only getting to 150 psi. I need to work through section 8.1.4 in the maintenance manual before I go too far.
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