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Cleaning out old R12 A/C lines

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44 years of crud in my evaporator, condensor and A/C lines, any thoughts on flushing them out?  New compressor.

What if I put a 5 gallon can of gas on a ladder and siphon it down through each item, then blow them out with air?

I'd like to start with a nice clean system. 

The process

The items to do it with

My first question is are you putting 12 back in or converting to 134? If the systems was closed the whole time and the compressor did not melt down then a simple conversion is all that is needed, although a flush would not hurt but if staying with the original hoses you really should not flush since the old oil is what is sealing the original hoses. If you are going to flush and convert it would be a good idea to go with new 134 compliant hoses. Then be absolutely sure to look up all the specs for the right amount of oil for each component. The compressor is usually filled but you have to find the specs for the dryer, condenser and evaporator and add the appropriate amount of oil. I does not hurt to drain the new compressor into a measuring cup just to be sure it comes out close to the proper amount just to be sure.

And you ARE replacing the dryer and expansion valve aren't you?

I wouldn't use gasoline, acetone maybe but I would definitely replace the hoses.

I have used this on a couple of retrofit jobs.
Cools well and doesn't seem to have any issues.

For flushing....Buy the solution made to flush systems.  Any left over gas fumes could be bad news under pressure and heat.


That stuff is butane and is not at all recommended to put in an automotive system. Any leak at all is a recipe for an explosion! And the temperatures in the high pressure side of the system are far above the ignition point of the butane. There were all kinds of bulletins put out when R12 was being eliminated and these hybrids started hitting the market.


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