1974 A/c

[flaco1801]

guys took out vette today....last time i used the a/c it blew so cold i saw ice on the back of the compressor.... now it wont blow cold, the compressor turns... any ideas for a quick fix? thanks...

 

[6880 Mike]

You need a shot of R-12.

 

[Rex S]

guys took out vette today....last time i used the a/c it blew so cold i saw ice on the back of the compressor.... now it wont blow cold, the compressor turns... any ideas for a quick fix? thanks...

When you say the compressor turns, do you mean it comes on like it should (center section turning)? Does it cycle rapidly? If it does it could be low on charge and it's time to convert to 134a or one of the R12 drop in replacements such as Duracool R12a or Freeze12. If your system still has the hoses with the old hose clamps on them, the system won't take to 134a well. I really recomend going to a good A/C shop.

 

[flaco1801]

thanks guys... compressor turns normal.. the bottom vir pipe gets cold... ill get a charge and see what happens...

 

[Tom73]

...If it does it could be low on charge and it's time to convert to 134a or one of the R12 drop in replacements such as Duracool R12a or Freeze12. If your system still has the hoses with the old hose clamps on them, the system won't take to 134a well. I really recomend going to a good A/C shop.

EPA does not reconize any "drop-in" replacements for R12.

Freeze12 is a blend of 134a (80%) and HCFC-142b (20%). Duracool 12a is, according to EPA website, "Flammable blend of hydrocarbons; insufficient data to demostrate safety".

There really is only two ways to go. Stay with R12. Convert to 134a. No other true options.

tom...

 

[geekinavette]

"no other true options"? Don't agree with that at all.

Hydrocarbon refrigerants work just dandy...been using 'em in three vehicles for years (Envirosafe). Non-toxic and environmentally friendly...unlike R134 (a known carcinogen...check the MSDS). Sure they're flammable...as is just about every other fluid running through the engine (including R12 and R134 as soon as oil is added).

Just because the all-knowing <cough cough> EPA doesn't "recognize" something doesn't mean its not out there.

 

[Rex S]

Thanks geek, I get soooo tired of explaining Duracool to people some times I just give up. Duracool's flash point is about 300F higher than 134a (check the MSDs) but Duracool is listed as Flamable and 134a isn't. I'm not even gonna guess why. Duracool is slightly more efficent than R12 and about 35% moreso than 134a. DC is allowed to replace R12 IF the system does not cool well on 134a (in a conversion) but 134a must be tried first and found lacking. DC does not require barrier hoses, but they are a good idea, and runs at much lower head pressures than 134a. Now with that said, go to the EPA's site and check out the soon to be required "new" refrigerant (yep we gotta change again as "they" kinda missjudged 134a's impact on the air quality). The "new" refrigerant looks a whole lot like ............ waite for it ....... hydrocarbon refrigerants used in Europe, Canada and most every where else in the world. Always remember that the US was about the last country to approve modern headlamps.

 

[geekinavette]

Ehhh somebody's making a s**tload of money on R134. This country is not about what's best for the people any more...its all about a handful making as much $$ as they can.

Screw 'em, I'm gonna use my own intelligence and what I KNOW works, and works so much more harmlessly...regardless of what the EPA publishes.

(guess I'm in a quite rare pissy mood today :W )

 

[geekinavette]

But ya know...none of this really helps the original poster (sorry!).

I would first make sure the system is charged properly...and not just give it a shot of refrigerant assuming that it is low, as that risks overcharging the system. Maybe it is low, maybe it isn't...and if the lines are getting cold, but air out of the vents is not, then it could very easily be something else. Like maybe the hot water valve to the heater core is stuck open or something silly like that?

 

[Tom73]

Legal Status of HC-12a ®, DURACOOL 12a ®, and OZ-12 ® | Alternatives / SNAP | US EPA

4. May hydrocarbon refrigerants be used to replace CFC-12, commonly referred to as "Freon® ," in cars?
No. It is illegal to use hydrocarbon refrigerants like HC-12a® and DURACOOL 12a® as substitutes for CFC-12 in automobile or truck air conditioning under any circumstances.

 

[geekinavette]

Only because THEY (the EPA) have not satisfactorily "tested" automotive applications. HCs are legal for use in industrial refrigeration systems because the vented (cooled) air is not directed towards human exposure (AC vent vs. a freezer for example). So, I'm supposed to sit around and wait for them to make this safety determination for me...when I can read the MSDS for both products myself and clearly see that HC refrigerants' flash points are considerably higher, have no known toxicity issues (its organic for crying out loud, where R134 is a known carcinogen) and have no negative environmental impact (R134 is not completely "safe" here either). Ain't happening.

Legally...R12 may be legally replaced with R134. R134 may be legally replaced with HC based refrigerants (as far as Feds go...states may vary).

Those EPA regs also specify certain variations of HC blends ("HC blend 2...etc). I have no idea what that means and which brands fall under what "blend" categories.

 

[tracksnblades1]

guys took out vette today....last time i used the a/c it blew so cold i saw ice on the back of the compressor.... now it wont blow cold, the compressor turns... any ideas for a quick fix? thanks...

Whether you decide to use the original refrigerant or the R134A replacements, I would consider R12 systems were engineered and designed for R12 refrigerant pressures and empathy. R12 works well in systems deigned for R12 as R134a systems work well respectively for systems designed for them. While some of your system may be similiar to R134a systems, I believe there may be a change in the condenser design, from serpentine arrangement to puseudo parallel in the later designs. Neverless ice on the back of any ac/compressor is an undesirable condition. Liquid refrigerant of any kind is non-compressable in any compressor, including the frigidaire eight/cylinder piston type. Good luck on your AC project.