[Elfer]

Any thoughts on the Autozone off the shelf recharge kits?

http://www.id-usa.com/how_to_recharging.asp

[hoophead]

Lame. They are just measuring the pressure, which is a poor indication of the state of charge since it varies as a function of temperature and humidity. You might get it to sort of work, but it will not be optimal.

I don't claim to be an AC expert, but to really do it right, you need to purge the system and then charge with a scale (by weight).

There are also high/low pressure charts (if your car manufacturer has them) as a function of temp/humidity that will get you close, but weight is the preferred method.

[Lupin..the..3rd]

With a/c charging "close" isn't good enough. A little low is OK but not optimal. But if you over-charge by just 10%, efficiency of the system drops by 40%. It really does need to be exactly the correct amount, something that's impossible with the $20 DIY kit.

This is one of those things I pays my $ for a professional to do it.

[Potomac-Greg]

Originally Posted by Elfer

Any thoughts on the Autozone off the shelf recharge kits?

http://www.id-usa.com/how_to_recharging.asp

Call me crazy, but for $22 I used such a kit to fix my 944's A/C last week. Maybe I got lucky. Best $22 I've spent in quite a while.

[Vicegrip]

If pressure/temperature measurement of state of charge is lame then I and many others in the HVAC industry are screwed. You can charge via pressure / temp just fine in most systems. (Some such as small cap tube systems often seen on cheap cube fridges are better total charged and if the system wad dead empty you should leak test and pull a vacuum first) I do HVAC work every day this time of the year and test and charge via pressure and temperature all the time. Humidity has little influence unless you have a evaporative cooling tower on the roof. When you have 45 pounds of R22 in a single loop and 6 loops to a singe roof unit and 5 roof units on one roof you can't pull and charge via weight.

Read the directions and follow to the letter.

[Noah]

Originally Posted by Vicegrip

When you have 45 pounds of R22 in a single loop and 6 loops to a singe roof unit and 5 roof units on one roof you can't pull and charge via weight.

i have no idea WTF that means

[Potomac-Greg]

Originally Posted by Noah

i have no idea WTF that means

Me neither. But for $22 and a 15 minute investment of time, I now have A/C.

And I think he is agreeing with me. The "can" setup I bought had a decent gauge, and when hooked up it was basically zero, and after pumping it into green/blue, I sweat less.

[BlackTalon]

Originally Posted by Potomac-Greg

, and after pumping it into green/blue, I sweat less.

Lemme get this straight... If you pump this into Green and Blue students you will sweat less?!?

Holy cow, all the instructors will be buying cans of this stuff!

[Vicegrip]

Originally Posted by Noah

i have no idea WTF that means

Originally Posted by Vicegrip

When you have 45 pounds of R22 in a single compressor loop and 6 loops to a singe roof unit and 5 roof units on one roof you can't pull and charge via weight.

I will type slow for you. It means it would take all day to remove a single charge and store it. Your home air conditioner is a single loop system and has about 3 pounds of R22 in it. The HBL Mercedes shop alone has 5 roof top units. Each unit has 6 compressors and each compressor moves about 45 pounds of R22. It is like 6 "souper" big house systems in each unit and 5 of them on the roof. I have about 450 home AC units worth of refrigerant in use on that one roof. Each unit is is big as a metro bus and you can walk around in side the filter compartments. When it is over 100 deg on the roof I have been known to take a break inside a blower unit. A bit loud and the 50 mph wind will suck the paper out of your shirt pocket but oh so nice and coooool.

[BlackTalon]

Originally Posted by Vicegrip

I will type slow for you. It means it would take all day to remove a single charge and store it. Your home air conditioner is a single loop system and has about 3 pounds of R22 in it. The HBL Mercedes shop alone has 5 roof top units. Each unit has 6 compressors and each compressor moves about 45 pounds of R22. It is like 6 "souper" big house systems in each unit and 5 of them on the roof. I have about 450 home AC units worth of refrigerant in use on that one roof. Each unit is is big as a metro bus and you can walk around in side the filter compartments. When it is over 100 deg on the roof I have been known to take a break inside a blower unit. A bit loud and the 50 mph wind will suck the paper out of your shirt pocket but oh so nice and coooool.

Better not be dropping the access panels onto the roofing membrane...