So, our 78 PC AC has not worked since I pulled it out of my dad's barn about 6 years ago. I was thinking about a simple recharge, but I am positive it has not been converted to R134a. Amazon has a product that claims to be compatible with R12 systems.

https://www.amazon.com/RED-TEK-Refri...12+refrigerant

Any thoughts? Also, should I add an AC stop leak to be safe? I typically hate doing those types of things (for obvious reasons), but I don't use the car enough to justify a major AC rebuild. Thoughts are appreciated!

 

Any automotive AC shop can check your stock system for leaks and top up R12 if needed. I would be wary of a product claiming to be compatible with both types of refrigerant.

 

I would only use R12. Have a vacuum pulled on it an make sure the system holds and any residual moisture is boiled off.

 

see my post in this thread. https://www.corvetteforum.com/forums...-to-r134a.html

that redtek stuff according to their msds is 100% alkanes. Alkanes are flammable hydrocarbons, mostly methane/ethane (natural gas). I would not use it.

 

usually if a system has sat empty for a long period of time it will have lots of moisture in the system since it has been "breathing".

To get the moisture out it requires drawing a vacuum on the system for a period of time to allow the water to boil off. Harbor freight has a vacuum device that can be used with a decent compressor to get a vacuum.
http://www.harborfreight.com/air-vac...ors-96677.html
I used one of these for several years and it works pretty good as long as you have a good air pump that can run for 20 to 30 minutes straight.

The filter/dryer may be saturated, or it might not, hard to say. Usually it is replaced to be certain it is not obstructed.

Then you got to wonder why it's empty in the first place. Typical is the seal on the pump shaft is bad. You may fill it, but it will most likely leak out again. How quick depends on how bad the leak is.

That red tek R12 looks to be possibly a good replacement for R12. I would not be concerned about the flamability of it, gasoline is far more flammable and it sits in an open carb on these cars.

If it's worth the gamble to you go ahead and get the vacuum pump at a minimum in an attempt to get the moisture out, then fill it and see what happens. It might work, or you might just be out $75.

Otherwise you'll need to spend the $$ and/or time to get it fixed.

 

a leak in a gas line drips liquid fuel, if a hose in the AC gets a leak, pressurized flammable gas fills the engine compartment...you can use ammonia or propane as well if you want, but like I said in the other thread, know what you are dealing with, and decide what your level of comfort is. personally I wouldn't want to add another potentially fatal failure mode to an old ac system, but that's just me...

 

Stay with r12, there is plenty on ebay.

 

I've experimented with the propane based replacements and they work rather well in our older systems.

I've seen lower head pressures and lower vent temps using these types of R12 replacements.

The Gov. is making it harder to get these in the US, they are used widely oversees,

Neal

 

There should be no issues at all with just pulling a vacuum and re-charging the system and see how long it holds. Then its your decision to stay with re-charging or fix it correctly.

I would suggest fixing it correctly but i understand your position

Neal

 

Thanks for all of the great feedback guys! I like the thought of checking the system with the Harbor Freight vacuum pump first. Only $19 and it will be a good excuse for a couple of beers in the garage.

 

I bought the harbor freight gauges and vac pump for @$200 and it's more than paid for itself. I see everyone saying R12 is easy to get and for the last 15 years I couldn't get it in NJ anywhere. The guys who did have it were scared to death to let it go. So I had the conversion done for r134. I'm pretty sure the system needs to be flushed in some way before recharging. That's why I paid a shop to do it years ago.

 

Draw the vacuum on the high side port, (the fitting NOT on the compressor) and monitor the level of vacuum on the low side port ( the one on the compressor). The pump does not come with hoses. so at minimum you'll also need a hose to connect to the high side and another hose with a gauge to connect to the low side.
This kit has both those. It will screw onto your r-12 fittings and also has 134a fitting that come with it.
http://www.harborfreight.com/ac-r134...set-60806.html
Or you can try to source them separately.

 

I'm in Flemington, if your certified its very easy to get, but expensive. I just bought a case off Ebay.

 

I just bought a 20lb container on CL for $250. And you can get a license on the web for $20, I did.

 

That's the way to get it in a large can. Smoking deal at $250.

 

If you can get R12....use it......but only if the system has not been converted to R134.
The thing that most fail to realize is that R134 is not as efficient as R12....so in an A/C system that was designed for R12.....it will not work as well.....
A friend gave me three cans and I will be using the Vacuum pump....

It will work fine with 134......but you will not be able to hang meat in there.....

Jebby

 

I agree with Jebby. That being said the 134a system can be made good with a few modifications.
Mine was 134a converted when I bought it. It had the stock cooling clutch fan and the only thing done in the conversion was to add 134a charging ports.
It was kind of cool, but not nearly what it should have been.
I decided to put in additional insulation in the floor, convert to electric fans with a new radiator, put in a C4 blower and add two shutoffs to the heater core.

The electric fans made a significant difference in the temperature of the air flowing from the vents.

The C4 blower made a significant change in the volume of that cool air getting delivered to the cabin.

The insulation under the carpet created an effective barrier against heat from the outside and the engine compartment.

I first only put in one heater core shutoff valve and the heater core still got hot over time, adding unwanted heat to the cabin. The second shut off on the other hose eliminated that source of heat.

Now it is a meat locker in the cabin if I want it to be. My wife, who likes her A/C, will complain of it getting too cold if I don't cycle the a/c off periodically.

 

Yes sir....getting more air through the condenser at low speeds is an excellent way to make a 134 system less noticeable....

Jebby

 

I hope they also replaced the hoses, the oil, the O-rings, and the desiccant as none of those are compatible with R134a....sometimes you can get away with original hoses if they are barrier type.

 

Stock hoses. Most likely changed the filter dryer and and orings associated with it. Other than that it is stock components as far as I can tell.