A/C Flush?

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A/C Flush?

Postby mike8668 » Tue Jun 28, 2005 5:11 am

Hey guys...My father in law has a 92 cavalier that we want to retrofit to 134. my neighbor has a Robinair evac,recycle and charge machine that he will put on for us. he knows the basic operation of it, but he is strictly a BMW tech and he really does not know about the older systems like this. Now what is the flush procedure? What do we use to flush the system(we have access to nitrogen from a home HVAC tech)? I plan to change the acc and OT. Emptying the oil out of the compressor is straight forward right? Tip it over and over to get thte oil out?
Any help is greatly appreciated....MIke
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Postby James » Wed Jun 29, 2005 4:49 am

You might also want to replace all the orings with r134 compatible ones (hnbr, the green ones), they're cheap and good insurance. You can buy flushes on the market, many people just use mineral spirits, lacquer thinner, or brake parts cleaner. Pour through components, except compressor , mufflers, Ot, etc. (basically just plain lines, condensor, and evaporator). Then blow all out with plenty of dry shop air (the nitrogen you mentioned is even better).. If you remove the components (which makes flushing and drying easier) from car; flush, blow, bake in the sun for a while, and blow some more with plenty of air or nitrogen. Just before you install the orings let them soak in compressor oil for a couple of minutes. Also apply some oil to the thread connections. As far as the compressor goes do the following: Take the compressor and turn it upside down to let the old oil run out of the line connections (this may take 1/2 hour, oil flows slowly). Then the following is how you flush it using new oil, and only new oil nothing else; pour about 4 ounces of new oil in it, turn the whole compressor in all different directions (each one lasting about 10 minutes). The goal here is in a sense to wash out the compressor. Then turn the clutch (shaft) about 20 times and turn it upside down to let the oil run out again for about 30 minutes. Then fill the compressor again with about 4 to 5 ounces of oil from the systems recommended total, tape over where the line connections go, and stand it up on the clutch for about 30 minutes. These steps will help to get the seals well lubricated. Once it has stood on the clutch for about 1/2 hour it is time to install and connect the lines. Once done, then turn the clutch (shaft) for about 30 times this will additionally help oil the seals and move the oil out of the compressor and into the lines (oil sitting in the compressor upon startup can damage it). When you go to vacuum the system, pull it for about 30 minutes and let it sit for a good long time to make sure there are no leaks (preferably overnight). If no leaks then pull good a vacuum for atleast a good hour, more like 2 and charge. If you have any more questions feel free to post.
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