So my AC does not exactly blow cold. Has been recharged with R134A by my mechanic. He explained to me that R134A needs higher pressure that old R12 systems cannot cope with, so you have to live with less efficient cooling. Currently I am mostly driving with both windows open (Toronto, summer temps 26+ deg C). Not fantastic.

However I gather that R12A is an option (propane) that should work better and is readily available here. Is it a question of just purging R134A and recharging with R12A? If so, how to purge, and how much R12A would I add?

Anyone been through this and can share experiences? (Obvs assumes rest of AC system up to snuff.......).

Quentin

 

Have a qualified shop do leak check and evacuate (remove) all the old refrigerant. Do any maintenance required and go to the Propane based refrigerant instructions. You do not need to pull a vacuum, 2 1/2 cans is approximately what you need. You can installed by weight or by low pressure filler gauge. I prefer the low pressure filler gage method. Instructions are on can. You can get pre-mixed cans with oil, leak check dye, and leak sealer. First can goes in with compressor not running. You may find it listed under the name ES-134A or ES- 22A as EPA wants all to move away from R12 and R134a labels as it is now getting confusing, as to original and acceptable replacements.

https://envirosafe.se/en/instruction...refill-your-achttps://www.es-refrigerants.com/?site=int

https://www.es-refrigerants.com/products/w/id/173/t/enviro-safe-r134a-replacement-refrigerant-w-dye-6-oz-cans-cases-1030/related/true/details.asp

Rgds
David

 

I've used the various hydrocarbon systems for about 20 years and they work well. The amount is about 1/3 of an R12 system, so if the original system called for 3 lbs of R12, you would use 1 lb of propane. Actually, the ideal is 22% iso-butane and 78% propane. The iso variant is important, not n- butane, as they have different thermodynamic properties. I usually charge in a 165g can of the Ronson butane (comes in a white and red can) and the remainder with propane.

I charge with the ac on and fans on high and a thermometer in the vents. Charge until I see the drop in vent temperatures plateau and then level off and not fall any further when more is added. The compressor should be cycling at this point, not running continuously. I also spray down the condensor with a garden hose to remove the heat. I'm typically aiming for around 25 psi on the low side and 150-175psi on the high side. With everything off and the engine cold, at an ambient of about 20° you should be seeing system pressures of about 70-75 psi.

However, a major problem with the XJS is the amount of debris that accumulates between the radiator and condensor. I have pulled some and seen radiators 85% blocked. If you have not done that cleaning, I would do that first. It's a big job, the radiator has to come out to do it properly and there are no shortcuts. Getting rid of the heat is critical to a functioning AC system and unless you can be certain the radiator and condenser are clean there is no point in doing anything else.

Ideally, you should get the R134 removed and recovered, then you pull a vacuum on the system and watch the gauges to make sure it doesn't leak off for at least half an hour. Once you have passed that test, then you charge the new refrigerant into the evacuated sytem. You will need a vacuum pump and the proper gauge manifold and hoses to do this. If you buy the replacement can ( Redtek, Duracool etc) you will need a can tap to attach the cans to the charging hose and to puncture the cans safely.

With everything clean and properly charged, you should be able to get air out of the vents at 3°C.

 

I disagree for 3 reasons.
1. Safety: if you think of the fire triangle, you need fuel, air and a spark to get fire. Introducing air into the fuel removes a level of safely for no good reason.
2. AC performance: Air is a non-condensable, it takes up space that could otherwise by taken by refrigerant and it doesn't contribute to any cooling, so it reduces the AC performance.
3. Charge longevity: Without pulling vacuum, you don't know if you have a leaky system or not. There is no point in charging refrigerant into a leaky system, you'll be doing it again in a short amount of time. Safety also comes into it, avoiding leaks with a flammable refrigerant is a good thing. Usually the only reason someone is asking about AC is because it has quit, so chances are very high the system is already leaking. Not fixing the problem and just recharging is a bandaid solution.

 

Its the manufacture that says not to pull a vacuum. It is in their instruction sheet in "RED".
Pulling a vacuum will confirm a leaky system, but it doesn't tell you where.
The shop that removes the old fluid that should not be released into the atmosphere, also has sniffers that can confirm where the leak is coming from when they pressurize the system.
The shop I worked was every effective at pinpointing small leaks. that I fixed before servicing with the new refrigerant.
Rgds
David

 

I have a hydrocarbon gas detector sensitive down to 5 ppm. Once I have evacuated the system and determined there is a leak I put in about 10 psi of propane and then run my gas detector over each joint. I can usually locate a leak very quickly.

I think not pulling vacuum is their way of making it a quick and simple repair - most people won't have the proper gauge set or vacuum pump. It certainly goes against good AC system practice to charge into a system with air in it..

 

I believe the point of pulling a vacuum isn't just leak detection, but removing moisture from the system (which is more important).

 

• DO NOT USE IN AMMONIA SYSTEMS!
• DO NOT PULL A VACUUM ON THE A/C SYSTEM.
• If you plan to pull a vacuum or are charging a larger system or dual air system such as on a van, suburban, or SUV, use Enviro-Safe Industrial R134a Replacement refrigerant.
• Enviro-Safe R134a Replacement with Dye can be used in all R134a applications, including pre-1994 automotive that have complied with the US EPA Snap regulation.
• Bring your a/c performance back to the original cold air!
• This is the original Enviro-Safe Refrigerant that we first introduced over 20 years ago.
• 1 can of Enviro-Safe R134a Replacement refrigerant is equal to 1lb of R134a.
• Operates at lower head pressure
• If you use the R134a Replacement with Dye, you cannot pull a vacuum because the product comes in a less expensive can to keep costs lower for the customer.
  If you are charging something like a dual air system in an SUV, you need to use the Industrial 134a replacement.
• Offers improved cooling properties and performance
• Compatible with most refrigerant oils
• Non Ozone depleting
• Non Global warming
• R134a can thread
• Use up to 60% Less
• Made in America!
• Enviro-Safe has been manufacturing hydrocarbon refrigerants for over 22 years.

· DIRECTIONS FOR USE
NOTE: You must check and repair all leaks before charging!
1. Shut off compressor.
2. Recover existing refrigerant into suitable container.
3. Check for any leaks in the A/C system.
4. Connect gauges and hoses with compressor off.
5. Do NOT charge this product in a vacuum state.
6. To install product, invert can and install product liquid on low-pressure side.
7. After minimum charge, test system for leaks. If no leak is detected, turn compressor on high, add additional product to achieve correct pressure. DO NOT EXPOSE TO ANY IGNITION SOURCE.
8. This product is flammable to open flame/spark and should be leak tested with dye charge, UV glasses, an electronic hydrocarbon leak tester or soap bubbles. If leak is detected, ventilate area, evacuate system, repair leak and install new product as instructed
above.
9. If pressure and temperatures are correct, shut off compressor and engine, disconnect gauges; install service port caps and system label in clearly visible area.
DO NOT OVERCHARGE. Fill low pressure to manufacture’s specifications. In some cases, overcharge the system. Overcharging the system may clearing the sight glass might affect cooling ability and performance and may damage the A/C compressor.

· Please refer to the manufacturer's specification prior to recharging the a/c system for proper pressures.

· DO NOT overfill the system.

· DO NOT exceed 60 psi on low pressure port. The low-pressure port is generally the larger diameter line from compressor.

· Flammable to an open flame or spark, proceed with caution if used in systems designed for non-flammable refrigerants.

· DO NOT smoke or use spark, or flame when using any refrigerant, refrigerant support product, other flammable products, when servicing air conditioning equipment.

· The Temperature Pressure Chart is specific to the temperature of refrigerant when inside of the a/c system. These PSIG pressures are not the operating pressure. The Temperature Pressure Chart displays the readings to charge on manifold gauge, to your a/c systems to refrigerant. ..........

If you want to pull a vacuum, you must release the vacuum before charging the system.
With R12 and R134 you must pull a vacuum to remove moisture, and you charge in to the system with the vacuum in place. This is to remove the airborne moisture that with R12 & R134 will cause internal system corrosion. Per the manufacture's literature, The propane mix is tolerant of airborne moisture and prevents it from being release in to system in a manor the causes corrosions.

Rgds
David

 

I've never heard of that brand, but I looked up the SDS for their 134 replacement that says to pull vacuum and it's also a blend of hydrocrabon gases, so that line about not pulling vacuum makes no sense to me from a technical point of view.

 

It makes sense when you read this little tidbit in the instructions:

"you cannot pull a vacuum because the product comes in a less expensive can to keep costs lower for the customer."

It has nothing to do with what is correct for the system, it's that the cheap can will likely implode.

 

I guess it's because I use a gauge manifold, but I couldn't connect the vacuum pump and a refrigerant can at the same time. Doesn't make logical sense either, you wouldn't want to vacuum the can, that would simply dump the refrigerant to atmosphere through the pump.

 

Guys,
Thanks so much for your thoughtful responses.
I will probably get the system emptied and then recharged with R12A. If Performance is still lacking will investigate further.

 

Using a gauge manifold, can't you attach the vacuum pump to the yellow hose and after pulling the vacuum, close the valves. Detach vacuum pump from yellow hose, attach the can, then open valves? I think that is the scenario the instructions would be referring to.

 

Yes, that's how I do it, but the cans are under significant pressure. Even after discharging into an evacuated system, I usually have over 50psi residual pressure left in the can. I usually then start the car and turn on the AC to have the compressor suck out the remaining refrigerant from the can

 

I have a vacuum pump and did pull a vacuum after I change out the "receiver dryer" (serviced new dryer with oil).
Before starting the serving the system, I did release the vacuum.
I used 2 cans and 1/2 of the third. First can of refrigerant with oil was added without A/C system running. Second can of refrigerant with sealer was added with compressor running. I added 1/2 of the third can (refrigerant only) and hit my ambient temperature adjusted, low pressure target with the A/C system running at max cooling.
I used the standard one hose & gage installation kit for normal auto store R134 arctic air servicing. It was very simple to do your self. If you are worried about moisture, definably replace Receiver (system filter) Dryer. (less than $30).
Rgds
David

 

One reason for the reason for the dryer is that moisture reacts with the freon and makes hydroflouric acid, so that corrodes the system from the inside out. Another reason was you don't want ice forming at the expansion valve and potentially blocking it.

I've never used the one hose on a can type, I've always used the 2 gauge manifold. Mind you, I almost never used the premade cans of refrigerant either, I do a "homebrew" of butane/propane. It's much cheaper, I can recharge a system for about $6, whereas here the premade cans are about $15-20 each.