A/C question
 

Recharge day.

Which side is the Low pressure Which side is the High pressure?

Is the low pressure the COLD side and the High pressure the HOT side when the A/C compressor is running???

If you are not trained at working on A/C you might want to leave it to the professionals.

I just had a very good friend taken to the emergency room when he was fiddling with a A/C hose and it burst on him. Got a full shot of gas to the face and blinded him for a while. This system can hurt you if you make a mistake. He was out of work for a week over this...

The high pressure side is the one coming out of the compressor with the smaller tubing or hoses. Low pressure side is the one coming out of the compressor with the larger hose or tubing.

ALWAYS USE GAUGES IF YOU ARE NOT 100% SURE OF WHAT YOU ARE WORKING WITH! Hooking a freon container up to the high side will turn it into a hand grenade. They are well known to explode if not done correctly.

Not trying to scare you but do not need another person going to the ER over A/C repairs.

The low side gets cold and the high side gets hot. I agree with Joe that you better have a good understanding of what you are doing if you intend to mess with the AC. If you are just a bit low on refridgerant, a recharge may be the ticket (assuming it still blows "cool" and it has been awhile since a recharge), but you still should monitor the pressures as you top it off, otherwise you wont know how much to put in. I fixed a leak in my '79 SC and recharged over 1 year ago with 134 and it still is working fine, but I did have a vacuum pump and gages to use.

Re: A/C question
 

Joeaksa has pointed out some good warnings for you.

But, to answer your question: in a normal running system, a/c system on (both center floor console knobs turned fully CW... to the right),
engine running, and <b>engine deck lid down</b>:
..... we'll take you to a safer area to fut's around here: if you open your front trunk, pull back your carpets and open the trap door (aka "smuggler's box") you will find the evaporator box. On the driver's side of the cavity (LH side when sitting in the car) you will see two rubber hoses, the smaller diameter one with the 45 degree fitting connecting to the expansion valve, which has a round "hat" on the top and a few copper coiled tubes coming from it. This line coming into the valve is from your receiver drier. This is going to be the liquid high side line. With the system running this line is usually warm to hot.
Just below the valve is a larger diameter rubber hose that has a 90 deg fitting attached to the evaporator outlet.
This is the low side of the system.... this hose runs back to the suction side of the compressor. This pipe or hose connection should be cold ... usually sweating. And, if the system is running very well you'll find back at the compressor the fatter suction hose Joeaksa mentioned will be cold or sweating too (watch out when you poke around the engine pulleys when the thing is spinning, I saw a fella lose a finger one day).

And you have the receiver drier located against the back side of the driver's LH front wheel well. With "floating ball " driers and R12 the system is "about" full when the refrigerant floats the ball just about to the top of the round site glass. With simple non-floating ball site glasses its full when the glass gets full. With R134a you don't use the site glass but rather you use the P&T or Pressures and Temperatures method of charging which is more accurate for overall system peformance...... which leads us to the question.. Do you really want to approach this job or would you rather be cutting the grass? Not trying to kill a fun day for a DIY project its just that some DIY projects require more tools and working knowledge than others.
2 cents.

Search around Pelican here and you'll find lot's of reasonable posts for the DIY on a/c. But at Joeaksa pointed out.... sometimes, for the once in awhile ac recharges it simply is not economical to pursue, but you can have some fun chasing the problems.

cool, thanks for all the info. One more question....

I was told by a HVAC guy that you can mix R12 and R134a. After reading a few sites, It would appear that only in USA you cannot legally do that. But physically it is fine

Am i correct?

pmajka..please wear good eye protection at a minimum..and long sleeves, etc. that will help protect exposed skin. i've also known of someone badly injured fiddling with theirs. i just don't mess with a/c anymore unless the system is already discharged. r12 and r134 are different size molecules..don't know of any advantage to mixing these.
ryan

Do NOT mix these two gasses, they are totally different. I could care less about legally, these two gasses are not to be mixed. As well the oil needed for a R134 system is not the same as the oil used with a R-12 system. Legality is one thing but compatibility is another.

It needs to be one gas or the other.

Also, Kuehl does A/C work for a living and knows what he is talking about. He also builds several systems and add-ons that make the 911 A/C system work much better, so he is a good source of information. I am a trained aircraft mechanic and pretty good at A/C but this is his world.

thanks again for the info...i always ask here at Pelican before touching the car. Think i am going Enviro safe. will have to delay AC till next week..

I have used ES-12 for years on my cars and have no problems with it. Am not going to say anything more as I do not want to try to influence you one way or the other but no matter which gas you use in your A/C, pls either know what you are doing or get someone who does to help you with it.

My $.02

Listen to Joeaksa... He knows what the hell he is talking about!

Quick note to add that I haven't run across here Joe...
After running almost a year with spectacular performance of the ProCooler r/d and Industrial ES12, my cooling was not quite up to par this summer season... Most likely to the original refrigerant hoses still being in place. You know, the ones with microscopic pin holes...

The refrigerant charge was slightly down... I mistakenly thought that by just topping off the system with more ES12 woould do the trick.... It made no difference... Brad form Redlands told me to evacuate the system, and put in a fresh charge... Lo and behold, I actually read the instructions on the can, and it said the exact same thing! I did it, and the performance has returned. Something about there being a specific mixture for ES12. Only a certain portion of that mixture escapes through the pinholes, and adding new messes up the exact combo of gas? Eventually, I will step up and purchase new barrier hoses, and that should eliminate the issue... However, for $18 to fill up an empty system....

One thing that Patrick mentions is the molecule size and pin holes. R-12 and ES-12 are about the same sized molecules I believe. R-134 is much smaller in molecule size, so if you have the original hoses and system it tends to leak out faster.

ES-12 is different from the other gases. In the old days we would shoot R-12 in the system until you did not see bubbles in the sightglass. Cannot do that with ES and have to go by weight. Also if your system takes 3 pounds of R-12, it DOES NOT take 3 pounds of ES. Talk to who you buy it from, they can help you here.

yep..take it from a guy with a degree in organic chemistry here..what joe says is true - r-134 is a much smaller molecule and thus far more prone to leak out of the original non barrier-styled hose. if you don't have barrier-style hose and wish to upgrade to r134, consider this upgrade even though the recharge cost is much less with r134.

btw, welcome to the '5-figures club' there, joe.. :)
ryan

joe, pat, where did you buy your ES 12 and

How many cans to fill up an evacuated system???

This is EXCELLENT advice.

Autorefrigerants.com

Per Joe's suggestion, I used the advanced industrial ES12a.

2 to 2.25 cans should do it...

Per the sticker in the engine compartment of my car, R-12a capacity is listed at 39oz.

6oz. of ES12a is equivalent to:

16oz. of HFC-134a
18oz. of CFC-R12

Ryan,

Thanks and did not realize that I was over 10k posts until just a bit ago!

Glad you have a degree like this, its hard for me to to fly airplanes for a living, let alone work with chemistry formula's!

Got the first batch off of Ebay then found a guy locally here in Phoenix. Easiest to look on Ebay or do a google search and you will find it.

Patrick covered the amount you need. I would buy 4-6 cans and that way you are covered for a long time.

well, as you know, joe..i miss flying the lear like crazy. a decade in aviation and it still stings to be apart from it. i flew commercially on southwest these past cpl weeks to spend time in new hampshire with my gf for the first time in several years. i cannot tell you how emotional it was for me to be sitting there and staring out the side windows for a change. on the way back, at night, i could still identify al the major cities by the runways as we'd pass over. hurt.. :( enjoy it, soak it all in for me, buddy..
ryan

If you review the EPA's website and locate the SNAP approved and disapproved refrigerant list,
start here:
http://www.epa.gov/Ozone/snap/refrigerants/macssubs.html
other reading material
http://www.facm.umn.edu/BAS/refrigprogram/FMRegRefrigerantPolicy.pdf

you will see some brands are a combination of different refrigerants. The question is how much of this or that makes a working combination. If you intend to shoot in some "X" brand or type refrigerant to make up a low charge of "Y" refrigerant..... you can run into problems related to pressures .... which leads to trouble when you try to diagnose a problem and mixing refrigerants is a "no no" (legal or otherwise) especially when you take the car to a service facility and they don't know what you did and they evacuate the mixture and it contaminates their recovery machine .... this tends to get the facility owner really annoyed, so don't bother doing it.

With regard to refrigerants other than R12 or R134a, our focus is strictly those two types for various reasons. So I'll leave the discussions regarding the other refrigerants to the peers here.

Let me know if you need help otherwise and we'll see if we can resolve your issues.

The day is done. Time to throw the dog in the pool and rough up the kids.

Enjoy your weekend.

I could not help myself. I had to post this picture again.
What a pisser!
Understand, this is NOT a promotion for fire extinguishers however I'd love to get the copyrights on the shot.

http://forums.pelicanparts.com/uploa...1153090323.jpg