360 AC Problem, High Low Side & Low High Side

Sounds good ..I reread your post and you said the low pressure gauge is good .. sorry I misread it earlier

Just for kicks ..when you do your test tomorrow with fans try it again with high pressure gauge while running





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So I confirmed .. the 360 uses the Delphi mechanical displacement variable compressor ..

So once the clutch is engaged ..it will run continuously.. no on or off .. that is controlled internally by pressure .. the higher the low side pressure the more aggressive the internal pistons pump .. once pressure is low the pistons hardly move

Look up Delphi variable compressor .. the number for your car is 6581290


If the pressures you mentioned earlier and in spreadsheet are accurate then I am going back to my original post of a weak compressor

Either way it is fairly cheap to evacuate and refill and see what happens ..that would pretty much leave a week compressor not pulling as hard / pumping as hard as it should ..


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Just a fyi .. I thought I had mentioned it here but looks like I mentioned in another thread ..with variable compressors and expansion valve ... looking at low side is not a good way to see if low .. you either have to use a sub cool calculation or evacuate and refill with exact weight .. what you did is a good test ..actually just recommended to on the other thread for a 458 .good job


In the end if you are low ..probably have a small leak..




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While it is old school to look at pressures it really doesn't tell you what the problem is or the condition of the 134a freon. The best place to start before you replace any parts is to:

1) evacuate the 134 from the system
2) vacuum it for 20 minutes and monitor the vacuum with a micro vacuum gauge for another 15 minutes with the pump off.
3) if it holds vacuum, then weigh in the correct charge.....pressures are irrelevant when you weigh in the charge.
4) then test the system and measure the pressures for comparison.

Anything else and you are starting in the middle and trying to guess what might be wrong. This same technique is the way any modern system (automotive, residential or commercial) should be charged.

Just so you know....I have HVAC licenses for Automotive, Residential and Commercial.

I know it is more expensive than simply adding 134 but if you like learning and you can afford a few tools.....they will pay for themselves. Plenty of online videos can show you how to use the tools. Also, in many places you can rent the equipment before making a major investment. At a minimum you need a set of gauges (which you already have), a recovery pump, a recovery container (to only be used for your 134), a refrigerant scale and a micro vacuum gauge.

 

The R3 is a great unit.

 

One characteristic of 134 or 410 is that an overcharge is just as bad as an undercharge when it comes to vent temperature. The way the gas compresses and expands becomes less effective in either condition. BMW systems are really sensitive. 10 oz one way or another and the vent temp is warmer.

 

@INRange

Thank you for your input and responses

I have a few questions that may come up later

Since the compressor was replaced and it is unknown if oil was calculated correctly .. any concerns suggestions there

Regarding oil ..how would oil be calculated when using the rg3 since I don't believe it separates refrigerant from oil ..should the process be run compressor for while before evac and then only evac from low side

Any insight would be great

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No concerns about the oil in the replaced compressor. If it was rebuilt or new it was filled with PAG oil (Polyalkylene glycol, or PAG, a fully synthetic hygroscopic oil made for automotive compressor components). If it wasn't the compressor would have locked up long ago.

Once upon a time, mechanics used to vent freon to atmosphere at an uncontrolled rate which caused the oil to vaporize as the freon escaped. Recovery machines are closed loop and evacuate the system slowly to ensure that the oil stays in the compressor.

I'm pretty sure you would have to take the compressor out of the car to drain and fill it. Overfilling it creates a new set of problems.

No need to run the compressor before evacuating it. I believe there is also a small dryer attachment you can get for the RB3 which will trap moisture, debris and any oil. I rarely find any oil in a dryer attachment.

 

Thanks so much

Any concerns that it is already too much oil in there .. improper replacement done ? If so any symptoms that would indicate overfilled of oil


Also I assume by your answer to evacuate from low side so that liquid (with oil in it) would not be a issue


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Not really unless someone put oil in there (via a service port) since it was installed. If that happened.....the only way to resolve it is to disassemble the system.

Just follow these instructions:

https://www.robinair.com/sites/default/files/570805.pdf

 

Thank you JD for your knowledgeable input here. This is one of the more instructive threads in a long time.

 

Yes thank you again ..have a good remaining of the weekend

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Ken

After hearing JD ..I would agree evacuate, change dryer , vacuum check for leaks and refill

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Need to find the leak

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That is after I believe Ken added some refrigerant so something is loose. As to finding it, if the system is still without freon I would keep a vacuum on it with a microguage and retighten the hoses and see if the loss stops. Unfortunately, these things generally leak at the compressor either inside the compressor or where the hoses attach on the back.

If he has already refilled it....the best way to find it is with a electronic leak detector. Don't screw around with propane....get a leak detector. It will make short work of the effort and not set you and your car on fire. The only downside is that you may have to evacuate the system again to solve the problem.

 

Ken,

In regards to flushing the system.......there is no reason to do that at this point. The only time I do that is when the compressor has gone boom. Once you find the leak....all will be good.

Oil to some extent is present throughout an in use system. The compressor has a reservoir and is usually filled at the factory or reman facility before it is sent out. The presumption they make is that there is no oil in the new system. When you replace a compressor on a residential unit....you always flush the lines before you braze on the new compressor. That removes any oil residue from the old system.

On cars it is largely the same story if you are replacing a compressor. The system cannot be flushed with the compressor attached.

 

Just to make sure.....you are pulling the vacuum through your gauges and when you reach 27-28 you close the valve on the gauge leading to the pump and switch the pump off? Just switching the pump off won't hold a vacuum. You would be surprised how many HVAC techs think that it will.