Ok I managed to connect my gauges to the high side and removed the low pressure switch to connect the low side. No reading at all, jumped the switch so compressor starts. Added one can of R12, low side goes to about 20, high side 25, added another can, low side stays about 25 and high side about 50, so now I used only two cans of 12. So the question is do I buy more 12 , convert now and take a loss, or am I overlooking something. Is it possible to add 134 to this system or is there consequences. I'm confused-------------

 

Think YOU"RE confused????????????????

removed the switch???what switch? you connect the low side gauge to the low side fitting on the dryer. Suction side.

Your high fittings are on the pressure hose to the condenser. That's where you connect gauges.

You "jump" the low pressure switch to get the compressor to run so you can add the 1st can.

If you did not evacuate the system, its a FAIL. You will never get the pressures right with air and moisture in the system.

R-12 and 134a do not MIX.

To change to 134a, you have to totally disassemble the system and flush everything. Get a new dryer, and change ALL the O-rings. New orifice too.

IIRC the systems takes 2.25 lbs of R12. These 'cans' are ONLY 12oz (3/4 lb) and THAT is a common mistake everyone makes ! ! ! One 'can' is not a lb ! Again, charge by pressures, NOT cans or weight.

Each year was a little different on how much gas they took, so check the FSM to make sure and make the adjustment if its a conversion....use less 134a than you would r-12.


people add 2 & 1/2 cans and wonder why its not cold yet. Because it still needs up to 1 more full 12oz can.....

This is why you charge by looking at the pressures.....

Its your call what to do now. You can add another can of r-12 and hope the pressure comes up. Or you can chuck the work and start over and go thru the conversion process which ain;t all that quick and easy.... or cheap. It'll cost you about $200 in misc parts, gas etc. And, about all day to so it.

Evacuate the system, everytime. Its not only about getting air OUT, its about pulling the system empty so its DRY inside. Moisture inside the a/c lines kills the cooling ability of the gas. It also causes corrosion when moisture mixes with the gases.

 

I just recently bought this car and the previous owner told me he charged the system by removing the low pressure switch at the evap and adding 12 there. The fitting on the dryer is either metric or some crazy fitting cause nothing fits not even 134 snap on's. So my gauges wre connected to the fitting where the low pres. switch would go and the high pressure fitting. I'd just like to get it to get sorta cool for the summer and do a conversion over winter. So i'm looking for the easiest and cheap way right now

 

It was probably filled with something like freeze 12 which is neither R12 nor R134a. Since it's an unknown, you really need to open it up and treat it as the unknown it is. Just putting R12 in it is wasting money.

 

I am sure I'll get flamed here but..... Get all the freon out with a vacuum pump then just fill it with 134a. If your ac system is operational you will have cold air. I have done this hundreds of times sine they banned R-12. Try it for yourself it is the cheapest way out. If it doesn't work you have spent very little compared to buying and installing all that extra stuff.

 

I have done the same thing. Adding 134A on top of an old empty R12 system without any of the recommended conversions. With a can tap, and old style 12 gauges, port adapters are not needed to do so.

It will not last!
The mineral oil that 12 uses for lubrication and PAG oil 134 uses are not compatible and will lead to compressor failure. The older cars using an A-6 compressor, {never used on a C4} will survive for a long time. The 80's R-4 compressor will die a quick death. It can be done and get you by for a summer. Considering 12 is not available over the counter, the choices are limited.

 

ok then I to believe that if I replace the accumulator and vacuum the whole system , that I can replace it with R134 and 134 proper oil---- without switching compressor.....

 

Back up a step....I assume you are adding refrigerant because the system was blowing warm air...consequently, that usually means a leak somewhere in the system.... if you take it in to a shop, they will also leak check the system which is important to do. I would go ahead and replace the compressor if it was an R12 system before and youre going to a 134A system now. Aside from removing the compressor and physically dumping the oil out of it, I dont know how to get the old oil out of the compressor.,, at that point, why not just buy a new or rebuilt unit? I just did my 93 Z28 system. I bought the compressor,dryer and expansion valve cost me $226.00 shipped to my door from Rock Auto. The shop I went to was another $145.00 to vacume, leak test and refill the system. I added the oil...1/2 goes into the compressor and 1/2 goes into the reciever dryer.

 

the place to ADD gas is on the DRYER, NOT the pressure line ! NOT the low pressure cycling switch ! That's new bubba rig and I'd guess wasteful if not dangerous.


The other fitting on the steel line going TO the condenser, is the HIGH pressure port. Never install a cheap 134a adaptor to that fitting/port. It strips that high pressure fitting and you can never use it again. That hose is around $50 IIRC....so use a GOOD adaptor that cost more than $1.50

You do NOT buy a new compressor to convert. you FLUSH the old one with alcohol or the flush stuff they sell. Its too easy.

all you have to buy is a $10 new dryer, with the 134a ports made on, a new orifice tube $5
a set of new O-rings $8 and $3 worth of rubbing alcohol.

Then you need your 134a and about 6 oz of oil.

That's ALL you BUY.

Rent the gauges and vac pump.

Take it all apart, toss the old dryer. Flush EACH section. Blow it clean with compressed air.

blow the compressor out with alcohol and air. Rotate the compressor with a socket to make damn sure you get ALL the fluid out. Flush it and put it all together.

Add 1 oz of oil at each place it connects, like the fittings, a bit in the compressor, some in the dryer. Be sure to ROTATE the compressor after you add a bit of oil to spread it to all chambers inside. Find out how much oil YOUR system takes. NEVER add more than it takes in the book. THAT is one of the BIG reasons why conversions FAIL,. Too much oil also kills compressors. your compressor cannot compress a liquid (oil). If the book says 6oz...add a total of 6oz...NO MORE. Pour 6oz in a cup and THATS all you get. Spread it around when the time comes to add the oil.

Reconnect it all and vac.
test the vac and make sure it holds at least 25hg for 30 minutes with the vac pump d/c.

Add gas.

So, you spent about $26 plus whatever your gas & oil will cost.

BFD and its done RIGHT.

the BS rumors about this need to end. Too many guys are screwing up because they do not have good information. $26 for parts to do a solid, and reliable conversion? It don't get any cheaper than that.

The only obstacle's are compressed air, finding a vac pump and decent set of gauges...
and......uhhhh damn! there is not one other good reason why this cannot be done on a Saturday afternoon and be done with it and have a GOOD working system. As good as 134a will ever do...

The charging port is on the DRYER. In fact, the NEW Dryer will come with 3 different ports to accommodate ANY of the new or old gasses...so there WILL be a port to connect the charge line to on the DRYER. Guaranteed.

The HIGH [pressure port (the one you do NOT want to blow off) is on the high pressure line close to the condenser. Add a screw-on 134a adaptor to this one. But DO NOT go cheap here. BUY a GOOD adaptor kit. The cheapo kits are a very cheap quality aluminum and they will ONLY allow you to connect ONE time then they are buggered up and will not hold the gauge fitting again...it will blow off and hurt you or who ever is close. The GOOD adaptor kits have fittings made of steel or high grade aluminum. They will last as long as that car does.
The 134a fittings will add another $7 to the cost. Sorry. Its now gone past $30 to do the conversion.

Follow these directions and buy this stuff, find the other tools and you CAN do this and do it RIGHT !

 

I agree with Leesvet.
Iirc you only fill with 85% of the system capacity when using r134.

Gary

 

Don't replace with 134A!...

R12 is designed for your system and cools much better!...

 

What's your hangup, GKK? Where are your facts? There have been thousands of successful conversions from R12 to R134A! Why are you adding to the confusion?

Leesvet, can you post a temp/pressures chart (low and hi) that shows the right way to determine when the system has the correct amount of R134A?

 

Most people will get the picture before trying the same repair on their car hundreds of times! But I guess there are a few slow learners. My condolences.

 

When all this changeover started, everyone was doing the expensive way to change over. Dupont's web site gave explicit directions on how. In about 4 months, they had changed their mind. Yeah, the two different oils used are not compatible, but, it will take 40 or 50 K miles for that to show up. By then, some other part of the system will fail. That is the time to replace and flush the system. If you just have a slow leak, put in some 134a. It will not cool as good as 12 does at low speeds. When the makers started using 134a, they got a LOT of complaints about cooling at slow speeds, they found out if they increased the size of the condenser by 30%, it made a big difference in low speed performance. Only down side was the cost of the larger condenser.

Check your system now for leaks (use a sniffer) if you don't have a big leak, add another can of 12.

 

I WOULD if I knew where I saved it....somewhere in the "docs" files in my PC...

IIRC, I found the chart by searching Google. I was looking for 134a min and max pressures vs temps or something like that. I was trying to figure out just how much heat was coming off the condenser on a hot day because the a/c was driving my coolant temps up by at least 25 degrees.

Roy, here are a couple that I found.....

http://rdl.com.au/doc/Pressure_Tempe...sion_Chart.pdf

Me posting THAT info from memory, in MY case is ill advised... Best to do the search !


I've found that the simplest set of words used when searching google will yield the best result.
ex:
R-134a pressure chart

For grins I also searched: R-12 pressure chart, so I could SEE the differences. It makes more sense as to why its not as good, but its close as you will see.

or perhaps

R-134a system pressure for automotive a/c -->which gave me this chart...

http://idqusa.com/faq/r-134a-system-pressure-chart

Somewhere there will be the info we're looking for ! Its just a matter of weeding thru all the 'stuff' ya don't want right now !
That's why my PC is such a mess, 'cause I'll save all this crapola for "later", whenever that is

Hope this helps

 

Dang!... Why so, angry?!

Facts, come from personal experience and information from a very reputable AC specialty shop in my area.

Had an 89 Vette with the R134A conversion which was done professionally and it Never blew ice cold!...I had it checked out numerous times by two different AC shops and they both said, air temps were normal for R134A.

I eventually bought my 91 Vette which had the original R12 system and had a Specialized AC shop go through it. I also, asked them about R134A conversions and they told me, they won't do them anymore because of customer dissatisfaction with the warmer air temps.

The tech also, showed me the difference between the R134A condenser and R12 condenser through a cut away core and explained about the difference in molecule size, extra load on the compressor, insufficient fan speeds, compressor Viton O-ring incompatibility, contamination if not evacuated correctly etc...

If the OP would've had a reputable AC shop check out the AC system, it could've already been fixed already and he wouldn't have wasted two cans of R12!...

I always, advise against the conversion because 95% of the conversions are done improperly (a proper R134A conversion will cost at least $800) and it's cheaper and less frustrating in the long run, to just fix the R12 system once and you'll enjoy ice cold air temps forever!...






.

 

I strongly disagree ! See post #9.

A good, proper and reliable conversion CAN be done for under $50 in parts plus the cost of the 134a and oil.
I've done it many times.

This includes Viton O-rings, new orifice (I prefer the "smart-tube") and totally flushing and sterilizing the system, firewall forward.

$800 shop conversions are $750 worth of shop LABOR charges.

Now, NOBODY said that a 134a conversion will cool as well as R12. That's impossible. The 134a has different properties and to accommodate 134a the system MUST be designed to use it. Cars that came with 134a will freeze your nutz off. Most conversions will NOT. A ford p/u with 134a will produce 30 degree air at the vents! Because it has a HUGE condenser and tremendous heat exchange it is extremely efficient.

I got a bigger condenser in my vette and did everything that can be done to a C4 to make 134a work and mine does produce air at the vents that's down around 40-45 degrees. but the C4 is not good for keeping that cold air so its easily lost. As long as I'm moving and do NOT crack a window I DO enjoy a cool, comfortable cabin. Previous conversions on other C4s did not work as well because they did not have the big condenser and self adjusting orifice tube...Loosing 5 degrees means a LOT in a/c efficiency.

Point is,
That a conversion that's cheap but effective CAN be done. Follow my instructions and I can assure you that the system will produce cold air. It will not be R12 cold, but it'll be close and it'll be cheaper to recharge when the time comes., Its a judgment call to switch or not. If R12 is available and easy to get, keep it ! BUT, if it is hard to find and too costly then convert and move on. I can tell you for a fact that even R12 fittings and adaptors are getting very hard to find. ALL gauges sets now come with 134a hoses and fittings and the r12 adaptors have to be ordered and bought separate.
That's another reason to think about changing...

 

Related question here. What's the switch on the aft side of the compressor? Is that a standard A/C part? (didn't come with my new compressor from Rock, for my '84)

Thanks.

 

Which is why I advise Not to do it!...Why take the time and expense for Less Cooling?!...

 

The switch, aft side of the compressor is the high pressure switch but didn't come with my new compressor from Rock, for my '84 and the old one was broken and is missing. Apparently, the newer designs use a different setup and the new compressor has a plug in that place.

All new parts, including seals, (exclude evap and condenser) were professionally installed. The system blew real cold (I was told) for a few days. It began cycling and produced warm air when I got picked up at PHX airport. Telephone call to the shop suggested a high pressure release of Freon (engine fan works).

Thx