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Full AC system evacuation.. how to recharge?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=59866		 Page 1 of 2
Author:  painemann [ Fri Apr 01, 2011 9:47 am ]
Post subject:  Full AC system evacuation.. how to recharge?
I took the condenser out to do the timing belt, now I need to recharge. How should I go about it, just go get some 134 at the parts store?
Author:  onthehunt [ Fri Apr 01, 2011 10:51 am ]
Post subject:  Re: Full AC system evac.. how to recharge?
Not meaning to offend/hurt feelings but judging by your post you should pay a shop to do it.
Author:  painemann [ Fri Apr 01, 2011 11:31 am ]
Post subject:  Re: Full AC system evac.. how to recharge?
onthehunt wrote:
Not meaning to offend/hurt feelings but judging by your post you should pay a shop to do it.

ha. all I was asking was if I need anything different for the KJ I have done it on other vehicles with the simple gauges but thanks for your help!
didn't know if the jeep required a certain pressure or not.
Author:  geordi [ Fri Apr 01, 2011 11:47 am ]
Post subject:  Full AC system evac.. how to recharge?
The first thing you should do is vacuum the system to eliminate any water or humidity that will kill your efficiency and possibly the compressor. Leave a vacuum pump on it running for 30 minutes to ensure a deep vacuum of 20 inches or more. A shop should be willing to do this for a small fee, a GOOD shop will do that as part of a normal charging process. From dead-empty vented like you have, add one small pressure can of lubricant and 2 cans of R134 (blue canned arctic freeze does work better than straight 134) with the engine running and on max ac. Check the pressures, low side should be between 25 and 45 for best operation, cold outside temps = lower low side pressure. High side should be 125-200, higher with hotter outside. The larger the spread between low and high, the colder your system will blow. It may take 3 cans to get the low side pressure up enough into the range.
Author:  GreenDieselEngineering [ Fri Apr 01, 2011 11:48 am ]
Post subject:  Re: Full AC system evac.. how to recharge?
If you have a shop do it, they will do a full evac of the system and put the correct amount of refrigerant in as well as the proper amount of lubrcating oil. Just adding the refrigerant yourself may not provide the correct levels and you will not be able to get out the trapped air since it was exposed to the environment. Ok...geordi just beat me to it!
Author:  painemann [ Fri Apr 01, 2011 12:46 pm ]
Post subject:  Re: Full AC system evac.. how to recharge?
Thanks, that's what I wanted to know! thanks guys.
Author:  Sir Sam [ Fri Apr 01, 2011 2:39 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
The system needs to be evacuated. If you just try to fill it with r134a it will not work at all.
Author:  warp2diesel [ Fri Apr 01, 2011 8:58 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
Yup, the vacuum boils all the moisture out of the system.
I do it for at least 1/2 hour.
To get the right amount of R-134A I have used a scale when I get it out of a big bottle and do the arithmetic if I am using small cans and stay with in the range. If the pressures are out of line when you put in the recommended amount, you may have gotten junk into your orifice tube.
Author:  tjkj2002 [ Fri Apr 01, 2011 9:00 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
Sir Sam wrote:
The system needs to be evacuated. If you just try to fill it with r134a it will not work at all.

X2........

Your system requires a specific amount of R134A which must be weighed as it goes in and it's not a even number.And the system must be evaced and hold 28-29 inches of vacuum for 30mins or more before even attempting to recharge.If 28-29 inches of vacuum can not be reached or kept for 30mins you have a leak.Oh and you must replace the o-rings on any line/fitting you disconnected or leaks will appear in that connection,must also use the proper AC o-rings as normal o-rings will not do and just leak.
Author:  BlackLibertyCRD [ Sat Apr 02, 2011 12:38 am ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
painemann wrote:
I took the condenser out to do the timing belt, now I need to recharge. How should I go about it, just go get some 134 at the parts store?



I'm a little confused, why take out the a/c condenser for the timing belt? Wouldn't that mean that you removed the intercooler and radiator also? I just did my timing belt and removing the fan and shod made enough room.
Author:  warp2diesel [ Sat Apr 02, 2011 8:56 am ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
tjkj2002 wrote:
Sir Sam wrote:
The system needs to be evacuated. If you just try to fill it with r134a it will not work at all.

X2........

Your system requires a specific amount of R134A which must be weighed as it goes in and it's not a even number.And the system must be evaced and hold 28-29 inches of vacuum for 30mins or more before even attempting to recharge.If 28-29 inches of vacuum can not be reached or kept for 30mins you have a leak.Oh and you must replace the o-rings on any line/fitting you disconnected or leaks will appear in that connection,must also use the proper AC o-rings as normal o-rings will not do and just leak.


I forgot to mention that I keep the gauges on and expect the vacuum to hold before I add in R-134A. When I was trained, we were told that it is easier to seal 1000PSI than it is to seal a vacuum. Getting your vacuum up to 28-29 in of hg gets rid of all the moisture that can cause big problems in your system. If the system is open for any period of time, I replace the receiver dryer too.New "O" rings are cheap insurance, I use the green or blue ones, not black on R-134A.
Author:  Wobbly [ Sat Apr 02, 2011 9:03 am ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
I think that the orifice tube is supplied as an integral part of the liquid line. The accumulator should also be replaced if its been exposed to the atmosphere. Moparpartsamerica wants more than $300 for the accumulator filter drier. It's available for less than $50 from online ac suppliers.


A mistake sometimes made is failure to purge air from the manifold gauge lines before connecting to the system. This will introduce non-condensibles into the system and make accurate readings impossible.

The air-powered evacuators sold by Harbor Freight and others are of dubious value.
Author:  Squeeto [ Sat Apr 02, 2011 12:51 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
Good information all around.
It would be nice to see a 'how to' in the tech section.

Wobbly wrote:
The air-powered evacuators sold by Harbor Freight and others are of dubious value.


What would be an example of an appropriate evacuator to use? Could this be bought for a reasonable price by the home mechanic?
Author:  geordi [ Sat Apr 02, 2011 1:21 pm ]
Post subject:  Full AC system evacuation.. how to recharge?
Flea bay is probably your best choice for affordable... I got a GAST electric vacuum pump with a self-oiling system for like $150, best purchase I've ever made. I had one of those air-powered units... Just don't waste the money. They don't suck...

I've never gotten a 28" vacuum from mine, but that is probably b/c I suspect the gauges are bleeding in at the car connection. It's possible that a larger pump would be able to overcome that by sheer volume, but I've also never had a problem with cooling leaking or weak performance with only a 22" vacuum for 30 minutes. I've done the same process on 10 different vehicles so far... All cold as ice after. I replace the orifice and drier if I am replacing the compressor, especially if the lines wipe out dirty with a q-tip. If everything was fine before you opened the system and it wasn't insanely humid (80% +) while the thing was open... Chances are that just the vacuum will be fine to evacuate any moisture that entered the tubes. The drier shouldn't have absorbed enough to even be concerned with.
Author:  Wobbly [ Sat Apr 02, 2011 2:35 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
I'd poke around the automotive ac forums for a vacuum pump suggestion. Check Craigslist for a used unit. It's important to change the vacuum pump oil before using the pump, since the oil picks up water and will prevent getting the best vacuum.

http://www.autoacforum.com/categories.cfm?catid=2
Author:  Joe Romas [ Sat Apr 02, 2011 5:05 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
Squeeto wrote:
What would be an example of an appropriate evacuator to use? Could this be bought for a reasonable price by the home mechanic?


A compressor from a refrigerator works well. I used one for years before I was given an old Atlas branded unit for service stations. Inside it has a refrigerator compressor :-)r
the only difference is the one I have now is in a nice plastic housing :seuss:

I was always told the system should be evacuated to 27 inches and it should hold it. And the longer the system was under vacuum the better :BANANA:
Author:  painemann [ Sat Apr 02, 2011 9:04 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
BlackLibertyCRD wrote:
painemann wrote:
I took the condenser out to do the timing belt, now I need to recharge. How should I go about it, just go get some 134 at the parts store?



I'm a little confused, why take out the a/c condenser for the timing belt? Wouldn't that mean that you removed the intercooler and radiator also? I just did my timing belt and removing the fan and shod made enough room.


I was having a hard time removing the fan nut with the hammer and adj. wrench method so I said screw it and took all the coolers out. Whats a few more $$ in this money pit!? A local shop that had already solved some wiring and ABS sensor issues said he would charge around $55-75 for a charge, not too bad.

Wobbly wrote:
I think that the orifice tube is supplied as an integral part of the liquid line. The accumulator should also be replaced if its been exposed to the atmosphere. Moparpartsamerica wants more than $300 for the accumulator filter drier. It's available for less than $50 from online ac suppliers.


A mistake sometimes made is failure to purge air from the manifold gauge lines before connecting to the system. This will introduce non-condensibles into the system and make accurate readings impossible.

The air-powered evacuators sold by Harbor Freight and others are of dubious value.


I did see the accumulator online for about $47, should I get one now, or just have it filled as soon as possible and try it out?



tjkj2002 wrote:
Your system requires a specific amount of R134A which must be weighed as it goes in and it's not a even number.And the system must be evaced and hold 28-29 inches of vacuum for 30mins or more before even attempting to recharge.If 28-29 inches of vacuum can not be reached or kept for 30mins you have a leak.Oh and you must replace the o-rings on any line/fitting you disconnected or leaks will appear in that connection,must also use the proper AC o-rings as normal o-rings will not do and just leak.


Good to know I need o-rings for the two connections, where would I find the correct AC o-rings? online?
Author:  tjkj2002 [ Sat Apr 02, 2011 9:06 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
painemann wrote:
Good to know I need o-rings for the two connections, where would I find the correct AC o-rings? online?

Any good parts stores will have AC o-rings kits for your vehicle,not that pricey either,there like $5-$10 here for the whole kit.You will want to pick up the correct PAG oil also to lube the o-rings,do not install dry and use only the correct PAG oil to lube them.
Author:  Squeeto [ Sat Apr 02, 2011 11:48 pm ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
:grim:
Hate to ask but what are the home mechanics using for refrigerant recovery?
Author:  Sir Sam [ Sun Apr 03, 2011 3:34 am ]
Post subject:  Re: Full AC system evacuation.. how to recharge?
I've had really good luck with my harbor freight venturi vacuum pump, that being said an electric pump IS better, one of these days i might spring for the $90 HF electric vacuum pump.

Squeeto wrote:
:grim:
Hate to ask but what are the home mechanics using for refrigerant recovery?


The ozone layer.
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