I have a Puron 2.5 ton condensing unit, I also have a 2 ton air handler (r-22), and I have a txv kit to switch the handler to Puron. Will this unit work at all in a small 800 sq. ft. cabin. I know it not designed as such but I already own these pieces and would like to use them. thank you.

The prior rely - "oh yeah" will lead you into trouble.
1st, if the R-22 is not correctly removed Completely from the system the new compressor with Puron (R-410A) will have a greatly reduced life expectancy.
2nd, matching a 2-1/2 ton condenser to a smaller 2 ton evaporator is not recommended - may work, but charging & efficiency is off the the charts.
3rd, WHY do you need a 2 or a 2-1/2 ton anything for 800 square feet? All I can assume is the is NO insulation, or it is all glass.

Suburbob should be thouroughly confused now that (2) Senior Experts/APP Volunteers have given conflicting advice.
Hello icehouse
There is a product produced by Nu-Calgon called Rx-11 Flush. this is one of the products produced with is spoke of in the following helpful article.

Tech Tip: Flushing Refrigerant Lines For Use with R-410A
07/15/2008
by Kevin O’Neill
When you replace an air conditioner or heat pump and upgrade from R-22 to R-410A, the ideal solution is to replace your refrigerant lines. This is because the mineral oil used in R-22 systems is not compatible with the new R-410A refrigerant and oil. (Note that about 3 to 5% of the compressor oil is circulated through the system, with the rest remaining in the compressor.
count = 'square300' + ++square300count;randomness = Math.random() * 100000;document.write('')R-22 is a hydrochlorofluorocarbon (HCFC) with an affinity for mineral oil, because of the chlorine atoms in the refrigerant molecule. R-410A is a hydrofluorocarbon (HFC) and it has no affinity for the mineral oil. There’s no chlorine in it, so the mineral oil in the system (refrigerant lines) that’s left over from the old system tends to hang up in the refrigerant lines and the new indoor coil. This reduces efficiency by reducing heat transfer in the coil. It can also cause unwanted chemical reactions with the new refrigerant.
R-410A uses synthetic oil called polyolester (POE), which is chemically derived from an alcohol. Moisture left in the system with the old oil breaks the new oil down and it changes back to an alcohol, ruining its lubrication properties, causing the new compressor to fail.
Customers would go through a real hardship to replace refrigerant lines, so some companies have developed flushing agents to remove the old oil and other contaminants from the refrigerant lines. Technicians can flush the lines by cutting the indoor coil loose, and then soldering the lines together indoors. Next, we inject the flushing agent into the liquid line port outside, with a hose connected to the vapor line port outside. The hose connected to the liquid line port outside discharges into a bucket or other container. We follow the flushing agent with nitrogen under pressure to make sure the flushing agent and contaminants are forced out of the system into the bucket. After the flush, we pull a vacuum on the system with a vacuum pump to evaporate any flushing agent left as well as to remove the nitrogen and any remaining air or moisture.
Flushing lines may not be absolutely necessary in all cases, but it’s inexpensive insurance against problems, similar to installing a new liquid line drier every time you open the refrigeration system.
Kevin O’Neill, CM, is the co-owner of O’Neill-Bagwell Cooling & Heating, Myrtle Beach, SC. He has 31 years experience in the HVAC service business, is a 24-year member of RSES, and was a finalist in the 2005 NATE Certified Technician Competition. Kevin can be reached at 843/385-2220; email koneill@ sc.rr.com.

The recommended pressures for the r-22 coil are lower than for 410-a (puron) so you will be more prone to a leak failure but I can tell you for sure that it will work because I have done it (shh! don't tell the manufacturers). Obviously it is recommended to replace both pieces of equipment but yes it will work just make sure your expansion valve matches your condensor and make sure your subcooling is right (10-14 degrees) and the most important thing is to make sure you are not flooding back refrigerant, this should not be a problem if the subcooling is right but it needs to be checked and it will depend on your return air temp. you should have a chart in the installation instructions of the condensor. Of course all this advice does you no good unless you have guages thermometers and an EPA certification.