I have a 89 RS that was originally a 305, that two owners ago swapped to a 350, swirlport heads, Holley street warrior carb, etc. It has everything for the AC to work, and it does work. Barely. It’s still the original R12 system. I got all the necessary things to recharge the system, jumped the low pressure switch to make sure the compressor clutch would activate, then refilled with some R12 I got off Marketplace. It’s held the pressure, doesn’t seem to have any leaks (no major ones at least) and compressor kicks on when the AC is turned on. It does however kick on and off constantly until the car is warm, even with the AC turned off. It didn’t do that before it had freon added to it. The system was evacuated before adding the R12. It’s still not blowing cold, but it’s not hot. It’s definitely working just not cold. Needless to say there is issues. Unless somebody has an easy immediate fix, then I have some questions about upgrading. My dad has a 2000-2002(?) tahoe with the 6.0 LS that I can take whatever I want from. How hard would it be to fit the system from that to my car? Is there a lot of extra things needed? Or is it just a plug and play fit. I’ve looked for threads related to this but I’m having trouble navigating this site. Anybody got a quick fix for what I have going on? Or have any info on swapping the AC system from a newer LS?

 

Oh and i also saw some people are using Air duster in place of r12? Thoughts on this as well?

 

Works great but requires the same steps as a R134a retrofit. Needs new barrier hoses, system needs to be flushed, PAG 150 for a GM compressor, install the biggest parallel flow condenser that will fit, use a Ford Red 0.062" orifice tube. My last system rebuild/conversion from R12 cools like this in near 100F ambients with the engine at 2,000 rpm. Idle is in the mid-upper 30s but still plenty cool. This was right before the cycling switch cut off the compressor to prevent freezing the evaporator core into a solid chunk of ice. Freezing the evaporator core is the limitation to any properly working AC system regardless of the refrigerant in use. R134a was used in -10F deep freezers for years.



Just to give you an idea this is applicable to any R12 era system. The specific components will change depending on what vehicle you are working on but the steps remain the same.

https://www.thirdgen.org/forums/cooling/787755-gm-r12-ac-system.html

 

If the compressor cycles constantly it's probably under-charged. Pressures should be about 35 - 40 low and 275 - 325 high, with the AC on Max, car's doors open, engine RPM at 1800 or so, and ambient temp of 85°. It should never cycle under those conditions.

It shouldn't run when turned off, any more than the light in your living room should be on when the switch is off. Be aware however that Defrost also runs it, since it dehumidifies the air and that makes it dry the windshield better, so expect it to run then.

A very common cause of poor AC performance is an inadequate main radiator fan. Remember, the system doesn't "generate cold", it MOVES HEAT. It does so by evaporating the juice which cools it, the juice picks up heat from the cabin air passing over the evaporator, the compressor compresses the warmed gas which heats it up greatly, then the gas condenses into liquid in the condenser as ambient air is pulled over it by the fan which transfers the heat in it to the outside world, then it repeats. If it can't send the heat out into the world at large, it can't absorb more from the cabin.

Yes you could theoretically swap the compressor from the truck into your car. Not really anything else. All it would take is abuncha custom-made brackets, pulleys, lines, and other such stuff. I'd put it in the "if you have to ask" category though.

I've heard about using various other chemicals in AC systems besides refrigerant butt have no experience, interest, or comment.

 

Thanks for the informative reply! I really had no idea how that process worked into the making of cold air from hot air business. I need to dig into this car a little deeper. I know it has a trans cooler mounted in front of the radiator, so I guess that means the fan the previous owner installed isn’t able to cool as much since it’s cooling both the radiator and trans cooler. He said he never ran the AC and never bothered to try and recharge at all it since he got it from the previous owner. I was thinking maybe there could be a clog in there somewhere since it sat so long without being used, but since it does cool a little bit that makes me think there’s other problems like you mentioned.

 

Great info! I’ll look into that before I decide to go with a whole new R134 system!

 

I could dive into the technicalities of this but "air duster" is USUALLY just R-152a with ad-ins like bitterant. R-152a has a very similar Pressure-Temperature curve to R134a and R12, but should in theory be more efficient. HOWEVER, R-152a is flammable. Flammable refrigerants don't appear to be permissible in automotive applications under EPA 609. Theory says that flammable gasses could escape in an accident and pose a hazard to fire crews. That makes zero F%&$#ing sense when the lines are run next to GASOLINE, but I digress.

If you run R-152a, at least do yourself the favor of using real R-152a, not using actual cans of compressed air. The ad-ins could cause damage to the system. Or not. I dunno.

Source: I have my EPA 609 Cert and a Masters of Mechanical Engineering with a focus on Thermo/Fluids.

 

Ain't the new refrigerant they use now (R-1234yf) flammable along with most of the dumbass R12 "replacement" refrigerants?

 

R-1234YF is technically “flammable,” but better description would be that it doesn’t put out fire.

R-152a is basically the same propellant used in compressed cans, and I imagine you’ve held a lighter in front of one of those at some point.

Also, the R12 replacements typically aren’t above board. They can work, but they would get you in trouble if the letter of the law was followed.

It’s all a game of trade-offs. R12 is more polluting but more efficient, R1234YF is non-polluting but inefficient. R290 (propane) is only mildly polluting but explosive. R717 (Ammonia) is about as efficient as it gets and non-polluting, but toxic… quite literally pick your poison.

 

R1234YF is flammable but so is atomized refrigerant oil in any AC system. When the oil is atomized at high pressure during a refrigerant release it can readily burn.

The embitterant does not hurt the system at all. If it did I would have seen the effects a decade ago.

 

bumping because I am learning more about the vacuum lines. Previous owner said he deleted most of them, could this be causing my issue of it not blowing cold?

 

My concern around this is mostly that not every vendor uses the same thing and I can’t account for every vendor. Refrigerant is typically highly pure to avoid freezing in the loop, but I can’t promise that Walmart brand compressed air doesn’t have moisture in it or other edge cases in that vane.

Could it work? Absolutely. Could it be contaminated? Absolutely.

Also, I can’t promise that all compressed air cans use R-152a. I wouldn’t be surprised if some use something else. Easy to tell that by checking the back to see if it lists 1,1-Diflouroethane or not.

 

I mean, yeah. If the blend door is on hot and the vacuum lines aren’t pulling vacuum, it wouldn’t switch.

i’ll wait for more experienced posters to take over on that topic though.

 

It is also very possible small cans of R134a are contaminated as well.

 

They sure could be, but shouldn’t be, at least from a reputable vendor. The small R-134A cans are at least intended for the purpose of refrigeration. Compressed air, not so much. Six of one, half dozen the other though.