Do I restore my AC or?

Chris64 · 2025-04-18T14:39:05-0400

I thought I typed up this question before but I couldn't find it, so I probably never clicked "Post thread."

Anyway, I have the OG AC from 1974. The compressor label says it takes R12 (which seems to be available online still - Amazon). The line from the condenser to the evaporator appears to be leaking oil, the hose is oily anyway and there's a puddle on the chassis from it, I'm not sure if it has anything left in it.

So long story short; the system seems pretty simple even if I had to replace each part. Or am I missing something? Is it too difficult to find parts/a waste of money? Can I switch the pump to a more modern system easily?

Honestly, I prefer the stock AC over alternatives like Vintage Air, which I'm sure are great. Nothing about this truck is comfortable so I'd probably just pull out the AC before going that route.

So far I haven't been able to even get it to click on but I'm not sure I really want to as it's likely empty. So far almost everything I try to repair, I end up replacing so I'm just trying to avoid throwing money away.

Scott91370 · 2025-04-18T15:17:37-0400

I know your weather isn't as harsh as our's but I would fix it.
It is not hard at all to replace everything.
I would make sure to get the newer condenser so the refrigerant will be more effective. I'd have to do some hunting to find the one I bought - let me know if you need it.

Chris64 · 2025-04-18T15:50:43-0400

Scott91370 said:
I know your weather isn't as harsh as our's but I would fix it.
It is not hard at all to replace everything.
I would make sure to get the newer condenser so the refrigerant will be more effective. I'd have to do some hunting to find the one I bought - let me know if you need it.

Would that also require a different pump?

Tonimus · 2025-04-18T16:15:58-0400

I would replace the compressor too, yes.

Edelbrock · 2025-04-18T17:47:21-0400

A/C is pretty simple.
Power goes from dash switch to the low pressure switch, to the high pressure switch to the electromagnet on the pump. If the pressure is too low or tow high, it cuts off the power to the pump.

When charging the system, the can of Freon has a gauge on it, that shows what range you want to me in for pressure.

You can check for leaks by filling the system and then spraying stuff with windows to see what makes bubbles.

R12 Freon is not available to the general public and is not on Amazon. If it says R12 on Amazon, then its a lubricant or UV dye or something that is compatible with R12 Freon.

134A is the "new" type of Freon that is sold to the public. Some states and countries do not allow Any kind of Freon to be sold to the end customer. It can only be sold to businesses. Which is totally stupid.

edgephoto · 2025-04-18T19:17:38-0400

The stuff on Amazon is R12a which is marketed as a drop in 100% compatible replacement refrigerant. The Canadians use this regularly. I have zero experience with it. If you are going through the trouble of replacing everything, why not just convert to R134a and be done with it.

R134a is slightly less efficient but our trucks have systems that are way oversized, you will never notice the difference. Just pay attention to the amount of total oil in your system. Many people do not realize the compressor is shipped with oil in it. Drain that out of the new compressor and add the proper amount of the correct oil. R134a requires you to lower the charge by 10%. I have done hundreds of them over the years and only on some did I change the orifice tube/expansion valve. The operating pressures of R12 and R134a are very similar.

R12 has not been made since January 1, 1993. To buy a container of refrigerant larger than 2lbs. you need an EPA license. All auto technicians who service A/C are required by law to be certified. Our parts depots got audited by the EPA a few years ago and we had to have our dealers provide us with proof they have a certified technician in their employ in order to continue buying refrigerant from us.

It is pretty easy to get your license, Click here for MACS or here for ASE.

Ricko1966 · 2025-04-18T20:03:07-0400

If charging yourself, you'll want real gauges so you can see high side and low side,and a vaccum pump. You can make a vacuum pump from an old refrigerator compressor. As already stated switching to r134 is easy and cheap,replace your hoses,orings,and oil. As for not selling freon to end users,not stupid at all and hack mechanics brought it on to everyone. It was/is so common that your backyard guy will just keep recharging a leaking system because it's cheaper and easier than finding or fixing the leak.Why are they charging it? It probably has a leak.I am certfied I can't do that,I have to fix it or send it with no freon.No one should be able to just keep recharging a leaking system,so how do they stop that? Take the freon away from the general public,the good ones and the bad ones. And even at that, a well meaning homeowner charges their system,and there's an obvious leak,where's his recovery equipment? He doesn't have any,does he? Nope it just goes into the atmosphere.

edgephoto · 2025-04-18T20:43:08-0400

The whole regulation thing is silly. If you are trying to prevent it from hitting the atmosphere then stop selling 1 lb. cans at Walmart. As @Ricko1966 said the problem is not the pros, it is the backyard idiots who keep recharging a leaking system. Well them and the less the scrupulous repair shops.

Get some real gauges and a vacuum pump. Unless you want a project just buy a cheap one off Amazon or at Horror Freight. As long as it can pull a vacuum of 30 in.HG then you can boil off the water. I would do 30-60 minutes just to be 100% sure you give it enough time to boil all the moisture out of the system.

Chris64 · 2025-04-18T20:48:10-0400

OK - from what people are saying:
* It is reasonable to get my existing system working - which sounds good.

* If I need to replace components, I should get R134a, which makes sense. I'll need to switch out at least the compressor and the condenser for R134.

* I'm not sure what state my existing system is in other than the condenser has a small leak.

On a side note - I have about 5 pounds of the old refrigerant for homes (I thought it was R13 but I really can't say for sure). I had it from a really long time ago.

As for charging/discharging the system, I would probably leave it for the pros. It would be nice to be able to do it but it requires a lot of equipment to do it properly.

I don't know if the coolant is even low. I just know a hose has a leak that I don't think is refrigerant. Would it make sense to fix that hose first?

edgephoto · 2025-04-18T23:42:39-0400

Chris64 said:
OK - from what people are saying:
* It is reasonable to get my existing system working - which sounds good.

* If I need to replace components, I should get R134a, which makes sense. I'll need to switch out at least the compressor and the condenser for R134.

* I'm not sure what state my existing system is in other than the condenser has a small leak.

On a side note - I have about 5 pounds of the old refrigerant for homes (I thought it was R13 but I really can't say for sure). I had it from a really long time ago.

As for charging/discharging the system, I would probably leave it for the pros. It would be nice to be able to do it but it requires a lot of equipment to do it properly.

I don't know if the coolant is even low. I just know a hose has a leak that I don't think is refrigerant. Would it make sense to fix that hose first?

You do not need to change compressor or condenser to convert to R134a. You do need to drain all the oil and replace it. Make sure to measure what you take out of each component so you can put back equal amount of R134a compatible oil.

You do need to install adapters for the service ports. If you take it to a shop make sure they reduce the charge by 10% from what the sticker under the hood states.

Snoots · 2025-04-19T11:20:57-0400

You DO need to replace the Receiver/Dryer!

AuroraGirl · 2025-04-19T11:35:02-0400

edgephoto said:
The stuff on Amazon is R12a which is marketed as a drop in 100% compatible replacement refrigerant. The Canadians use this regularly. I have zero experience with it. If you are going through the trouble of replacing everything, why not just convert to R134a and be done with it.

R134a is slightly less efficient but our trucks have systems that are way oversized, you will never notice the difference. Just pay attention to the amount of total oil in your system. Many people do not realize the compressor is shipped with oil in it. Drain that out of the new compressor and add the proper amount of the correct oil. R134a requires you to lower the charge by 10%. I have done hundreds of them over the years and only on some did I change the orifice tube/expansion valve. The operating pressures of R12 and R134a are very similar.

R12 has not been made since January 1, 1993. To buy a container of refrigerant larger than 2lbs. you need an EPA license. All auto technicians who service A/C are required by law to be certified. Our parts depots got audited by the EPA a few years ago and we had to have our dealers provide us with proof they have a certified technician in their employ in order to continue buying refrigerant from us.

It is pretty easy to get your license, Click here for MACS or here for ASE.

gm says r12 to r134a you do 90% of the r12 fill, then subtract .25lb from the result

You would want to of course have all the r134a components possible like condensor and a new drier, and change orifice tube.
GM would have preferred a high pressure cut out switch installed, they did sell them

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15981985

but thats for use with a R4 compressor, id frankly disregard that specific use with the previous compressor type. A pusher fan that keeps airflow while idling would probably prevent the issue that they are designed to prevent

Do I restore my AC or?

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