There aren't really any pics to add at this point since there is nothing new in pulling a vac and charging the system so from here on, its pure art & science. After filling the pump with oil and connecting it via the yellow hose it spat out a healthy wisp of white smoke within the first few seconds. The gauge also shot to -30 just as quickly. Obviously this did not meet the standard for "deep vacuum" so I let it run for an hour then turned it off.
The big question at this stage was if it would hold the vacuum so I let it sit for another hour..and damn if the gauge did not move. Thank you Nylog Blue !!
The 2 main ways to charge are by weight and pressure. Pressure requires way more finesse as the variables are ambient temp, humidity, compressor speed and I will get to more on this later. Weight is weight, so I pulled out my digital scale again. The full cans weigh exactly 1 lb (454.4 grams) and hold 12 oz of refrigerant. Add 90.3 grams for the valve since I knew that last partial can would have to be weighed with it. BMW calls for 900g of r134a +/- 25g. Basically, 31.5 ounces which is bang on the often quoted 10% reduction from the 35oz r12 charge. Keep in mind that these specs are for a converted system using the stock compressor which has either had the seals swapped or was installed w r134a compatible seals. Either way, those compressors were designed to run on r12. more on that later.
I found at that its best to not to fully open the valve on the can as it will freeze even when you set it in a bowl of fairly warm water. Patience was the order of the day. I went through 925g of refrigerant and given that I burped the gauge end of the yellow hose every time I changed cans to clear out any air, I figured I was right where I needed to be. When the pressure in the system equaled can pressure I started the car so it would pull in the rest and the good news at this point is that the compressor engaged and the gauges noticed.
The big question at this stage was if it would hold the vacuum so I let it sit for another hour..and damn if the gauge did not move. Thank you Nylog Blue !!
The 2 main ways to charge are by weight and pressure. Pressure requires way more finesse as the variables are ambient temp, humidity, compressor speed and I will get to more on this later. Weight is weight, so I pulled out my digital scale again. The full cans weigh exactly 1 lb (454.4 grams) and hold 12 oz of refrigerant. Add 90.3 grams for the valve since I knew that last partial can would have to be weighed with it. BMW calls for 900g of r134a +/- 25g. Basically, 31.5 ounces which is bang on the often quoted 10% reduction from the 35oz r12 charge. Keep in mind that these specs are for a converted system using the stock compressor which has either had the seals swapped or was installed w r134a compatible seals. Either way, those compressors were designed to run on r12. more on that later.
I found at that its best to not to fully open the valve on the can as it will freeze even when you set it in a bowl of fairly warm water. Patience was the order of the day. I went through 925g of refrigerant and given that I burped the gauge end of the yellow hose every time I changed cans to clear out any air, I figured I was right where I needed to be. When the pressure in the system equaled can pressure I started the car so it would pull in the rest and the good news at this point is that the compressor engaged and the gauges noticed.
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