1951 & up, Air conditioning recharge

[Richardonly]

Gentlemen,

I had my air conditioner retrofited and recharged last summer and it need another shot to bring it back to the cooling it is capable of.

There is the high and low fittings of which I connected the can to the low side.  It did not appear to take any new coolant.

To the font of both of these fittings are two tin caps.  Behind these tin caps is a type of rod that looks like it can be turned.  MUST this be turned/opened to allow the new coolant to enter the system?

This old picture of the engine and air conditioning unit shows the caps (tin) facing the front of the car, and the low side nipple closest to you.

Thank you, Richard

[Dave Shepherd]

Usually converted systems have blue and red caps, maybe they will not fit the older cars, anyway it should be charged thru the low side which is the larger of the lines in the system, is this 134 or just an retro fit from the 50's with r12?

[dadscad]

Those are service valves, yes you turn the valve open to let the refrigerant in system until your charge is correct. Then close the service valve, next close the valve on your refrigerant container, then slowly loosen the connecting hose just a little to bleed the pressure in the hose.

Before you open the service valve, with the hose connected, leave the hose slightly loose at the service valve to allow a small amount of refrigerant to purge the air from the hose. Open the refrigerant container valve slightly until you hear a hiss at the compressor service valve, tighten the hose fitting then start the car turning on the A/C. Open the service valve enough to let the refrigerant in.

HTH,
David

["Cadillac Kid" Greg Surfas 15364]

Richard,
The valves on your compressor "appear" to the original (for that style compressor) back seating service valves with the R-134a adapters screwed on the original 1/4 inch flare connections used for R-12.
The "tin" caps screw off, revealing 1/4 inch square (at the ends) valve stems.

The valves are called back seating because when you turn them all the way out (counter clockwise) the service port (where you see the R-134a adapters) is shut off, allowing you to connect your hoses and guages.   With the hoses and guages connected and connections tight, slowly turn the valve stem clockwise (usually less than 1/4 turn will do it) and you have opened the service port of the valve to the system.
After you perform what procedure you will be doing, be sure to turn the valves (seems counter intuitive to turn the valve open to close the service port, but that's how they work) counter clockwise to again close the service port access, and then remove the refrigerant charging/testing hose connections , and replace the service valve caps.
You can get the caps that go over the the service port connections at any parts store that carries refrigerant supplies.
Be careful, wear protective eye-wear and gloves, you are working with a high pressure chemical that can freeze flesh on contact causing IMMEDIATE frostbite to skin and/or eyes.
Greg Surfas

[Richardonly]

Gentlemen,

Thank you.

From what you have written, I attach my coolant can hose to the low side, car is running with a/c on high, turn the rod on the low side clockwise until enough coolant is replentished, and then turn the rod "counterclockwise" to close it.  I then finish by removing the coolant can hose and replacing all caps.

As my 1st post stated, this was changed to the new fittings and coolant just last year.  The picture was BEFORE this was done, but did show the fittings.  Here is a newer picture of the engine compartment, but too far to see the valves.

Thank you all for the information and I shall let you know how I make out with it.

Richard

["Cadillac Kid" Greg Surfas 15364]

Richard,
In diagnosing a refrigeration system of any kind you need to first determine what is going on in the system.  This is done with a set of gages that attach to the low side and the high side of the system.  In you case you have the valves to do so at the compressor.  With the gages connected and the system pressures being monitored the high side and the suction pressures should be observed, the temperature of the air going over the condenser and the air on and off the evaporator coil (with the fan on high speed) measured, and a determination as to whether the pressures correspond with the temperatures you have read.  In most all of the "early" systems there is a refrigerant sight glass which shows bubbles when either the refrigerant charge is low, or there is a restriction in the system such as air or a plugged dryer.  Not to be an elitist, but in order to SAFELY work on an AC system, especially an older R-12 system with a substitute refrigerant an exact diagnosis by a knowledge-able mechanic is highly advisable.
An overcharged system can generate pressures high enough to blow hoses, condensers and lock up compressors causing physical damage and the danger of (if working on the car at that time) exposure to high pressure refrigeration in either liquid or vapor form. 
Unless you are experienced I would recommend you take your car to someone who is. 
Respectfully
Greg Surfas

[Richardonly]

Gentlemen,

Thank you once again for your aprecciated advice.

Last year I did bring my car to an experienced shop with the proper equipment and spent two hour with the technician as he checked the entire system out.  The only thing not done was bringing it back for the results on the dye test for leaks as it continued to work for many months.

Over the course of the winter in New England and not thinking to put the A/C on, while driving it from time to time, as it may have been 20 degrees out, perhaps some has leaked out.

I DID take it back to the shop yesterday, and in speaking with the same technician, he said he would be able to check it for leaks on Monday or Tuesday.  He also told me that your advice was correct regarding turning the valve clockwise to open it and admit more coolant.

Off the record, he said that I could try putting 1 can in and see if that brought it back, then just bring it back to check for a leak if I cared to.

I properly put 1/2 the can in the system and it is cold as the Artic.  YOUR information certainly helped and I had a big smile on my face!

Thank you, Richard

[pauldridge]

Richard,

I agree whole-heartedly with the previous post.  If you're going to be dumping more refrigerant into your system, you really owe it to yourself to get a set of proper refrigerant gauges.  You can pick up a complete set for R-134 connections for $60-80 and it will be a good investment.  Then you can have a better idea of exactly what you're doing to your system.

Adding refrigerant is one of those things where 'more' is not necessarily better!  Ideally, of course, you'd completely evacuate the system, then add a measured amount of R-134.  However, short of that rather drastic step, I've had 100% success with my on vehicles' A/C systems (5 in all) by adding refrigerant (on a nice warm day, preferably 80 degrees or more) while watching the pressure on the High Pressure side (red cap) until it reaches somewhere between 180 and maybe 210 or so.  That will generally guarantee a decent charge of refrigerant.

And, finally, if you have further problems with that ancient York compressor, I'd highly recommend that you spring $180 or so for a modern Sanden unit that will be more efficient and take a fraction of the horsepower (ever wonder why it takes TWO fanbelts to turn that beast?).  There are York-to-Sanden adapter mounting plates available all over eBay for next to nothing, so it will be pretty much a bolt-on conversion.

Enjoy a cool summer as I will here in Austin with my Sanden installation!