charging a/c?

[p24-1953]

okay im getting close to finishing the installation of my a/c and am now needing to get the system charged. the local shops want $150-$220 to charge and fill the system. i have a r/12 guage set, and can acquire a 2.5 cfm vaccum pump, with all of this what else would i need to fill the system? should i just leave it to the profesinals? can you adapt a r/12 guage set to r/134a? how do i do this?

[jd52cranbrook]

Not sure about changing, but that is a good price IF it includes setting it on a good vacuum for a period of time.. The main problem with AC systems, (mine) is moisture in the lines.

Shops around here want into the 300 area for recharging, but it does include testing and drying.

Any moisture in the lines decreases cooling dramatically. It's something I would leave to a shop. Then never disconnect anything in the line again. Once it's opened, you just cost yourself a recharging fee.

BTW those cans you buy at the store, junk in my opinion. If your system was low to begin with, then you have a leak somewhere, and needs to be fixed and vacuum.

I made the mistake of charging the system before I was really ready. Make sure you can set your pump aside with the hoses still connected if you need to move it off the engine.

[jd52cranbrook]

Now having said all that. I am sure there will be post saying its a piece of cake, lol

[p24-1953]

this is a brand new "hotrod air system" so no leaks that i know of.

[jd52cranbrook]

this is a brand new "hotrod air system" so no leaks that i know of.

I have a vintage air system myself. You have to understand ANY air that gets into the lines, that means during installation too, carry moisture, and needs to be vacuumed first, just like any recharging.

I'm just talking from experience, I've went both ways, me doing it, and shop. If you want a good working AC system, let a shop charge it for you. If you want to say "I did it myself", well then go that route.

[P15Mike]

That sounds like a avg price for evac & recharge . The labor op for this is about 1.8 hr mech time @ shop labor hour amount . So considering they're using R-12 , sounds like a decent deal . As far as switching to r-134 i believe you just need to switch all the seals to accomidate r-134 , no changing of hardware . Hope this helps .

Mike

[dezeldoc]

You can buy a set of R134 gauges cheaper than you can change yours over. just make sure you have all the right seals where they go and everything is tight, add the right oil and amount in the pump and system, hook up the vac pump and pull it down. after you have it down leave it sit for an hour or so and make sure their are no leaks, you can do this with the gauges. if no leaks start the charging and let it go! don't worry to much about the moisture to much as that is what the dryer in the system is for. MAKE SURE YOU DO NOT CHARGE THROUGH THE HIGH SIDE OR BAD THINGS HAPPEN TO THE CAN OF FREON!! Remember high side is the small hoses and low is the big hoses.

Edited February 17, 2010 by dezeldoc

[kencombs]

and, to be sure you get the maximum amount of moisture out, you might consider heating the metal components with a heat gun after the vacuum is pulled. The moisture is removed during vacuuming because it lowers the boiling point of the water, turning it into a vapor and sucking it out. In cold weather and/or with a marginal vacuum level that can be assisted with a little heat.

Somewhere there is a table that shows water boiling point at various pressures but I can't find it now.

Also, be sure to purge the charge hose of air before opening the connection to the system or you will readmit air when opening the valve. I just open the connection at the system and open the can valve a little, lets the freon push the air out.

You can buy a set of R134 gauges cheaper than you can change yours over. just make sure you have all the right seals where they go and everything is tight, add the right oil and amount in the pump and system, hook up the vac pump and pull it down. after you have it down leave it sit for an hour or so and make sure their are no leaks, you can do this with the gauges. if no leaks start the charging and let it go! don't worry to much about the moisture to much as that is what the dryer in the system is for. MAKE SURE YOU DO NOT CHARGE THROUGH THE HIGH SIDE OR BAD THINGS HAPPEN TO THE CAN OF FREON!! Remember high side is the small hoses and low is the big hoses.

[Plymouthy Adams]

You can go to Harbor Freight and for 45.00 walk out with your own R134 manifold set...evac the unit as it is new for 15 minutes min. to a vacuum of 28 inches , close manifold and ensure that the vacuum does not leak down..if you lose vacuum you have a leak..check fittings...unit will show leak under vacuum much faster than under pressure...if you cannot find the leak by thightening or inspecting for a damaged o-ring on assembly..commmon..due use refrigeration oil to lube the so-rings on assembly..if stillunable to detect place of leak, charge unit to 5 PSI on the low side and use leak detector..if able to find leak and repair without voiding the integrity of your system..continue charge to correct level..

the R134 manifold at HF is decent enough setup..inpsect for good hose crimps before leaving the store..their backset valves and quick connect R134 system is very user friendly..

[p24-1953]

okay im finnaly to the point where i need to charge the system. it has held a vaccum for a 2 weeks while i played with other things. what i need to know is the factory recommend XX lbs of refrigerant, but i had to run longer hoses than what they supplied so i could mount the compressor on the drivers side of the engine. should i need to increase the amount of refrigerant to compensate for the longer hose.

[Harvey Tank]

what have you decided to use? R-12 or 134A? I suggest you don't use R-12.

if you ues 12 and you have to take it to the pro. shop some day by law they have to remove the R-12 and convert to R134A. Per EPA regulations

[p24-1953]

its going to be r-134a thanks for the offer ruth1932 i will tkae you up on that.