i am working on a unit that is an INDOOR package unit. The condenser section is ducted with intake and exhaust vents. The evaporator section is open return. They are manufactured by Freidrichs,and their brand name is The Insider. They have a TXV and run on R-22. They are also heat pumps. The units are dated 1999. They are a RPITA to do anything to outside of change the filter. The unit was apparently really popular in Texas,but are now no longer made so any part is going to be aftermarket based on capacity and tonnage. The unit had a refrigerant leak which I isolated and remidied with new compressor at the owners request. the only thing is it had really foamy oil come out when I connected my gauges. i have seen this before but have never asked anyone what this is all about. I was told that someone put R-12 in this particular unit to fill up one of the leak down episodes. Is there any particular method or anything any one can recommend while doing these repairs. Keep in mind that replacement is not an option as I have already went over all the possible catastrophic failures that could go wrong. I had to replace the TXV in this unit too,which was discovered as soon as the replacement compressor was cranked up. This TXV was probally the culprit that took out the compressor.I flushed the lines and the coils thoroughly with rx11 and nitrogen and pulled a deep vacuum. I know some old timers and old schoolers will say "dont flush the coil "But if the flush is purged and vacuumed thoroughly all should be well. I weighed the charge back in according to the rating plate. The pressures are still fluctaiting but not as bad. I plan to remove the filter drier in three days and perform a triple evacuation and recharge the unit and see how it works. Right now even with the dancing pressures it is cooling ok. I just wanted some differing opinions on this.