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How much oil to replace after compressor change?

ScotY on Tue September 15, 2009 3:38 AM User is offlineView users profile

Year: 88
Make: Suzuki
Model: Samurai

I have an AMA a/c kit. There is currently nothing wrong with the system, it works fine. I want to replace the Seltec compressor with a used NipponDenso unit. I am planning an engine swap so need to use the ND compressor.

I will flush the ND compressor first and drain out as much of the old oil as possible. My question is how much new oil should I then put back into the ND compressor? What kind of oil to use to flush and replenish the system?

Are there general guidelines as to how much oil to replace when changing a compressor, condensor, evaporator, drier?

Thanks, Scot

HVargas on Tue September 15, 2009 2:00 PM User is offlineView users profile

There are guideline's to go buy when replacing individual parts and what amount of oil to add. However there is no real way to know how much oil to add other than to flush all of the major components and add the full system charge again. You are just playing a guessing game. I will never recommend using a used compressor either. Used compressors are so hard to tell the condition they are in and sometimes it is too late to tell if they are bad or not after they have contaminated the system. With the 134a system you can use either our BVA Auto 100 oil or the recommended viscosity pag oil to flush the compressor. To flush the other components we recommend our Hecat flush. We use it here and it works fantastic. That is the only way you are going to get the exact amount of oil in the system you need. Otherwise you could have too much/ too little and both are going to affect cooling performance.


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ScotY on Tue September 22, 2009 3:38 AM User is offlineView users profile

Hi Adam,

Thanks for the info. I've been reading about the Hecat flushing system...very interesting but a little expensive for the home enthusiast. Would you happen to know of any less expensive alternatives for flushing? I have one of those yellow Karcher power washers and it has a tip that pulsates like the Hecat unit. Not sure about running water through the components though.

I noticed on your website that you have universal filters but I didn't see one that you could put inline in barrier hose. Does such a filter exist? I have no hard lines in my a/c system.

I understand about a used compressor. Like a lot of people, especially in this economy, I need to attempt to save money. I read about the flushing procedure here using oil to flush out contaminants. It's a risk so I have not yet decided if I want to take the chance.

HECAT on Tue September 22, 2009 6:17 AM User is offline

A little expensive? - So is doing it over and over. Some DIY jobs require more than the skills. Just because you can DIY does not mean you can do it without the minimal proper tools or following the required procedures, does it?

Less expensive alternative? - It's got to be clean. Consider replacing the parts you are not going to flush.

Pressure Washer? - Potential pressure damage and water contamination. I would drop that thought.

In line filters? - The filter available here is for a hard line splice. There are none that I know of that will go in a hose. However there are some available that would screw into a connecting port or a screen for the suction port of the compressor.

Oil flushing? - This procedure is for rinsing oil oils out of a compressor and not a method to flush contaminants out of the rest of the system components.

How much oil to add back? - There is factory specifications for your vehicle called "oil balancing". This is the OE's method to replace a part on the assumption that the current oil is the correct quantity and is clean; basically a virgin system.

There is a lot of risk you are contemplating here in short-cutting the repair in an attempt to save money. Surely you would not be planning on draining the old engine oil and saving the oil filter, to use in the replacement engine; to save money.

Somehow we always find the time and money to do it again when our shortcuts come back to bite. Sometimes we can also be more lucky than good.


HECAT: You support the Forum when you consider for your a/c parts.


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