a/c evac help

[JTL]

I rebuilt the compressor 1 year ago so the r-12 and most of the oil is gone. The dryer should probably be replaced due to age the the system being open during my clutch job last winter.

I want to charge the system with 134a. I have a stand alone vac pump and a manifold gauge set. What is the evac procedure and specifically how do the gauges hook up?

Any tips on charging other than the obvious warnings etc. would also be appreciated.

Thanks, jt
-84 targa

[Hugh R]

Do a search on Jim Sims and A/C and you'll find everything you ever wanted to know. You should put 134a valves on the compressor and hose, read up on it and wear safety glasses. You always introduce it as a gas to the low pressure side. If you open the high pressure side while the can of 134a is connected with the charge valve open, it can explode in your hand. Best to get someone who knows what they're doing to help you.

[JTL]

Thanks-I did some searching last nite and got the basics. However, there is a lot of info which is pretty unclear. A bullet-pointed checklist would be ideal rather than a ton of 'if you don't know what to do let someone else do it or else boom' stuff.

For example: the two hoses at the compressor look pretty much the same size. Which is the hp side. Couldn't find a pic or nothin'. I'm surprised Griffiths.com didn't really help either.

Car hasn't been at a stealer for anything else so why this?

jt

[rfuerst911sc]

One of the hoses at the compressor should be larger in O.D. than the other and the larger one is generally the suction side ( low ).Your gauges should have 3 hoses a red,yellow and blue. I'm just going by memory but blue is low,red is high and yellow is for vacuum and refrigerant charge.Yuo will want to replace the drier and while out put an ounce of oil in it to help get oil distributed in the system.If you have additional questions feel free to PM me.

[ruf-porsche]

Originally posted by JTL
I rebuilt the compressor 1 year ago so the r-12 and most of the oil is gone. The dryer should probably be replaced due to age the the system being open during my clutch job last winter.

I want to charge the system with 134a. I have a stand alone vac pump and a manifold gauge set. What is the evac procedure and specifically how do the gauges hook up?

Any tips on charging other than the obvious warnings etc. would also be appreciated.

Thanks, jt
-84 targa

Don't do it. Keep with the R12. If don't have any R12 I can swap you even for 134A. Only my PORSCHE use R12 and I have enough to last me a life time. My other cars all use R134a which I need to buy in order to recharge the system. You are local in Chicago so I wouldn't have to ship the stuff.

If you need help in evacuating the system and charging the system I can help. PM me.

[Hugh R]

HP side is the one going to the condensor under the rear deck lid. With 134a you pour in an ounce or so of oil made for 134a, ask at the parts store, I don't remember which one. I bought a 134a receiver/drier for about $25 from a local NAPA place that fit fine. Your old R-12 hoses may prematurely leak out the 134a, it a smaller molecule (supposedly) than R-12. Never open the high side valve with the can tap open, that is what blows up the can in your hand. If you turn the can upside down, you will introduce a liquid slug of 134 into the compressor and can hydrolock it, which means it can break your compressor. Fill with the deck lid closed down and the hoses stick out, watch out for the fan. The reason for this is to semi-cool the read condensor, otherwise you can over pressure and blow your hoses, expansion valve, whatever. You may not be able to use R-12 gauges without a 134 adapter, or 134 hoses with fittings. Some gauges have both 12 and 134 hoses , ditto for the can tap, I think they're different. I took my condensors off and flushed them with isopropyl alcohol, it scavenges moisture and evaporates without leaving a residue, lots of crap came out of the condensors. Don't flush the evaporator, to delicate with the expansion valve, your liable to jam some dirt into it. pull a vacuum for at least 1/2 hour and see if it holds for another 1/2 hour before trying to recharge.

Wear Safety goggles. Refrigerant can blind you.

[JTL]

Thank you all for the replies.

I let the vac pump run for about 30 mins, closed the valves and let it sit. The low gauge still reads 30" after 6 hours. This is with the old dryer still in place. I did this to check for major leaks on the rebuilt compressor.

Advance autoparts has a dryer for $69 which appears very similar to the one Griffiths is selling. I'll check Napa too. The rear condenser is easy enough to flush; good idea. My gauges don't have adapters for 134, yet.

I guess it would be possible but prolly not the greatest idea to use the single hose/gauge that came with the kit to charge. When that gauge reads full then hook up the twin gauges for a more accurate reading.

Thanks for the R-12 offer Ruf. I don't really want to be dependent on something thats not available now or even less in the future, especially knowing for certain it will leak out of a 911.

Hugh, I will go at this with gloves, safety glasses and caution.

jt

[Goth]

If you fill with 134a, you may want to hook up the dual gages before full on the single gauge. I think 134a only requires ~75% of the volume vs R12.

I over filled mine and learned the hard way (busted hose). Now I have dual gauges.

[ruf-porsche]

Whether R12 or R134a you should always use the two gauges for the low side and high side.

[kuehl]

Originally posted by JTL
I'm surprised Griffiths.com didn't really help either.

Geeez ...... I fella can't even finish his beer without being interupted!

What are the basic steps to converting to R134a ?
The "basics" (general terms) are discussed at "Griff's" site:
http://www.griffiths.com/achelp/achelp3.html
The reason the details are not discussed on the site is obvious (GTI does not promote DIY with charging procedures because most DIY's don't have the equipment or experience). Simply, there is too much to cover in terms of the step by step procedures for recovery, evacuation, charge, test and troubleshooting. The FAQ list would eat up the server's hd.

Understand that I am not trying to discourage you. I'm simply telling you the facts:
A) there is much disinformation out there, and
B) there are a few marketeer's peddling "half-a" products to retail or end consumers; the products (such as canned refrigerants, ac system sealers, cheap service hoses and gauges, inadequate instructional materials and no tech support whatsoever) at big box autoparts stores.

But there are two very good sources for training manuals, which explain theory and practice, you can obtain which are invaluable, and that will get you up and going quickly:

1) Snap on Training Manual Air Conditioning ...ACT 279C, 1999 Available from local dealer, for local dealer information call 877-740-1900
2) MAC's, The Mobile Air Conditioning Society
http://www.macsw.org/selfstudy.php

Buy either one of the starter manuals noted above. Read it thoroughly a few times and then approach your car and equipment and I guarantee you, you will have far fewer questions when you reach the end.

Most importantly, if you do DIY, DO NOT try to save a few bucks buying inexpensive equipment. You get what you pay for and unfortunately on the professional side today the market is being flooded with chinese junk. This is not to say that if its stamped "china" it won't work. It means the a/c market in terms of tools is now being hammered down so much in pricing that the major distributors are not thinking, they are simply buying (importing) and distributing the least expensive products they can to stay "competitive" with (cough) Ebae ... and it is starting to bite back.

This year we started 100% inspecting and testing all R134a charge port adapters after we received a few field complaints of schrader valve failure "out of the box". There are basically two design types and most are being imported from the west. The U.S. importers or distributors, though "ISO" certified, are clueless to quality standards. These parts are being hammered out by old Brown and Sharpe screw machines or even new CNC machines, however the guts are being assembled by kids sitting on a dirt floor who are paid a dollar a day. The parts are then split amongst a few key western distributors and imported here in the states by another handful. They (the US importers) take what they can get and they don't complain about quaility because they are "playing the odds". And the same goes for the fittings you find crimped on the hoses. There are two major players in the U.S. One is an import for sure, its quality (configuration and tolerance) varies with every shipment.
The other (a well know U.S. firm) says they make them all here in the states, B.S. they are importing and the quality shows (I know first hand because we ship them back the rejects after another 100% screening program).

This week we returned two service manifolds to a distributor. Most of the service manifolds, flooding the market, available today come from the "west" perse and from only a few manufacturers. One service set was incorrectly mark for use with R134a however it did not have 1/2 acme threads, it had 1/4' flares for R12. The second manifold set had snap on couplers that were incorrectly designed: had a service tech used them he would be sucking air into the system unknowingly. And last month we returned to another supplier two low side gauges because they would not "zero out": meaning you could not determine how deep the vacuum was nor could you repeat what you did before; hence you would not know if you evacuated the system down low enough.
If you want to have some fun, take your typical service gauge set and look at the low side gauge and tell me if you can determine or read the difference (accurately) between -28" inhg and -28.5" inhg. You need a electronic digital gauge to tell the difference and a measurement in the micron scale is better than the inches of mercury scale when you are dealing with 40 feet of hose, two condensers and a evaporator and drier..... and you don't want any air mixed with your refrigerant.

So, before you start your DIY ac project, just don't know how to use your equipment, "know" your equipment.

[Jim Sims]

"Which is the hp side. Couldn't find a pic or nothin'.'

If you can't figure this out almost immediately upon inspection of a 911 engine compartment then you don't know enough of mobile A/C basics to be doing this job. Educate yourself and get some experienced help. The first time I did this job, I had a experienced person show me how to do it plus I understood how A/C systems work both by reading a refrigeration engineering text and a basic mobile A/C servicing text. It ain't rocket engineering but you have to understand what you are doing (open the wrong valve at the wrong time and you'll make a mess or worse) and you need the right equipment.

[Goth]

Originally posted by Jim Sims
"Which is the hp side. Couldn't find a pic or nothin'.'

If you can't figure this out almost immediately upon inspection of a 911 engine compartment then you don't know enough of mobile A/C basics to be doing this job. Educate yourself and get some experienced help. The first time I did this job, I had a experienced person show me how to do it plus I understood how A/C systems work both by reading a refrigeration engineering text and a basic mobile A/C servicing text. It ain't rocket engineering but you have to understand what you are doing (open the wrong valve at the wrong time and you'll make a mess or worse) and you need the right equipment.

Outstanding advice.... Get an experienced buddy to help.

May want to check out this site: http://www.epatest.com/manual609.html#TableList_6

It's a "A Self Study Course for EPA 609 Motor Vehicle A/C Certification ".

[JTL]

My ultimate goal is to get the car to go faster. I hear a good way to do this is to reduce weight? Maybe I should pull the entire a/c; it's gotta be worth a couple of hundred lbs. I mean - it's never going to work too well even in new/perfect condition. This way I'll save some dough and aggrevation, and won't get blown to bits while attempting to work on it.

Seriously speaking, I have a buddy lined up to help and just need to pick up and install a new dryer.

jt

[Jim Sims]

"it's gotta be worth a couple of hundred lbs"

more like 80 lbs