I bought a can of the self-proclaimed "best" a/c refrigerant do-it-yourself kit from Advance Auto, and this is my experience...

I got the top-of-the line $45 20oz version that comes with the built-in pressure gauge and follow the instructions to the letter. It took a long time to empty the can (20 minutes?) and the pressure never changed on the gauge (25 psi). According to the gauge and instructions the a/c system should have been full at around 42 psi.

I took it to my local independent Land Rover repair shop and mentioned it to the owner. He said that the can of freon is worthless because it doesn't have enough pressure to get into the rover's system. He charged me only $75 to evacuate the system for 1/2 hour and put the correct (measured) amount of freon in (along with a dye for any future leaks).

For me, this is a no-brainer: Pay $75 to have it done properly by professionals, or pay $45 to open up a can of R134a into the atmosphere and waste my personal time.

 

I always use cans. There is plenty of pressure in them for the task of recharging. What I don't use is the cheap gauge-hose combo thing on those quick charge setups. They are garbage. I use a cheap-o harbor freight manifold gauge set so that I can see pressures on both sides.

The problem with having a 20+ pound tank of r134a is that if you get a leak you lose it all. If you have cans you are much less likely to lose everything because of a leak.

 

Your LR specialist was slightly mistaken. Correct the can did not have enough pressure to fully charge your system. Once the AC system pressure equals the can pressure (all based off of ambient temps) - that's it - no more r134a will go into the system. But if you Put the can of R134a into a pot of hot water to increase the pressure inside and boil off the remaing liquid Viola!! more pressure inside the can of R134a. You need to increase the pressure inside the can to boil off the liquid r134a into a gas (pressure).

Or charge the system w/ liquid r134a which is the suggested method of charging R134a systems.. Turn the can upside down and pump in liquid.

There's more to maintaing a refrigerant system than what these " A/C Pro" people show on YouTube. It's complex chemistry. I always suggest taking into a certified licensed refrigerant facility

 

The pressure in the low side is reduced by the suction of the a/c compressor. When the compressor turns off you'll see the two side equalize eventfully, and you'll see what pressure the r134a is without being compressed or suctioned. The pressure of the low side is much lower than the pressure inside the can. There is over 100 psi at the can, and the low side is maybe 40-50. If you want to get even more out of the can, coors is right, you can heat the can with warm water. I also like to rev the engine up a bit to bring the low side pressure down a little more, then I turn the valve off, idle back down, and remove the "empty" can.

 

He lied to you, using the do-it-yourself cans is a great way to go and as for the pressure comment he made, those cans have the same pressure that his 5 pound bottle has.
He screwed you and if it were me, I would let him know you know it, and of course, never use him again.

 

I have to agree with disco mike.

Further R134a has a "0" ozone depletion rating. However, this stuff is not all glitz and glamour. that's how the unlicensed average joe can purchase a can off the shelf.

 

Remember if u overcharged it its bad like expensive bad it will destroy the comprossor .....yes you can do this yourself but if your low get the leak fixed ok ...I don't use cans j use thr 30lb tank





QUOTE=Duke;410421]I bought a can of the self-proclaimed "best" a/c refrigerant do-it-yourself kit from Advance Auto, and this is my experience...

I got the top-of-the line $45 20oz version that comes with the built-in pressure gauge and follow the instructions to the letter. It took a long time to empty the can (20 minutes?) and the pressure never changed on the gauge (25 psi). According to the gauge and instructions the a/c system should have been full at around 42 psi.

I took it to my local independent Land Rover repair shop and mentioned it to the owner. He said that the can of freon is worthless because it doesn't have enough pressure to get into the rover's system. He charged me only $75 to evacuate the system for 1/2 hour and put the correct (measured) amount of freon in (along with a dye for any future leaks).

For me, this is a no-brainer: Pay $75 to have it done properly by professionals, or pay $45 to open up a can of R134a into the atmosphere and waste my personal time.[/QUOTE]