Capturing freon for remodel job

How do I overfill the condenser (like when the unit was first installed , charged with enough freon to fill 25' tubing) before I break the connections to relocate unit. I heard you let the compressor pump against a closed liquid / discharge valve then close suction valve and stop the compressor,
Thanks
Jim

NO! This is how you smoke a compressor.

Do you have an EPA license to handle refrigerant? The fine is $15,000 and they do track you down!

This is not a DIY job.

1. You can't even buy some of the restricted refrigerants, and if you could they are very expensive.

2. It takes special equipment to install a refrigerant system. That equipment includes special refrigerant recovery systems and vacuum systems to get the air out of the system.

You are going to hire someone to make the system work. You are better off hiring them before you mess it up and waste a lot of expensive refrigerant.

Unfortunately, a license to work on refrigerant systems is a license to stick it to unsuspecting customers and charge 100%++ markups on equipment. You should get in touch with several vendors and get quotes on the whole job.

If it is not fairly new equipment you will probably get a better deal, and better and more efficient equipment, if you replace the system.

30 lbs of R22 has been running about $79 to $99 . But Dupont has already announced that the retail price going forward will be more like $199. This is in advance of 2010 when the phase out of R22 begins in earnest.

I've never heard of a condensing unit being "pre-charged" with refrigerant. Every unit I've seen has been delivered empty.

If your compressor has isolation valves, the compressor can be removed without discharging the system. I don't like this method, because a small amount of air does get in. But that doesn't address any additional lineset tubing required for the new location, and adjustment of the charge. HVAC isn't like MVAC where every vehicle uses a specified amount of refrigerant; each house is different, so each system will use a different amount of refrigerant.

Legally, you DO need to recover the refrigerant. You can recover the refrigerant without a recovery machine, but it requires a LARGE tank under vacuum. The refrigerant would then likely be treated as hazmat and appropriate disposal fees would apply. Many shops recover everything into a waste tank (and pay the appropriate disposal fees) rather than lugging around multiple recovery machines for each refrigerant. Most likely, you will need EPA 608 certification to purchase the refrigerant... hey, don't blame me, I don't subscribe to all the environmental BS either.

Also as a practical matter, many HVAC suppliers also will not sell to the public.

Condensors are often precharged for about 15' of line set, but that is because the positive pressure assures you that it was clean, and no possibilit of air/moisture intrusion. It does NOT eliminate the requirement to take a vacuum down on the system, to clear the lines; or the requirement to set system temps and pressures with a proper guage and thermometer set up.

They probably don't precharge systems anymore, but many years ago (70s?) they did. I put in a sears central air system and everything was precharged. You could not cut the tubing so you had to work with their lengths. But when it was installed you just flipped the switch. Very handy for DIY.

The Trane a/c unit I had installed last year was precharged at the factory. They had to pull a vacuum on the evaporator and lines, but then just opened up the valve and checked the charge.

Many split a/c units come with both the compressor and lines pre-charged. SOrt of like the hose for an air tool...snaps in place. No need to do anything except route it, anchor it, then snap it into the socket and you were ready to turn it on.