timb
Passed Driver's Ed
- Location
- Hampton Roads, VA, USA
- Car(s)
- 2007 Volkswagen GTI
Summer is coming, this means hot temperatures. Let's face it, the A/C system in most of our MKV GTIs is less than perfect.
The compressors are inefficient and prone to flat out blowing up.
The evaporators are small, the cooling fans smaller and to top it off it has to put up with heat soak from the radiator and intercooler.
What to do? Well, if your A/C isn't blowing cold, you might need a recharge. Systems lose refrigerant naturally over time. With the seals on our compressors, you could lose up to 25 grams over 3 years. That's about the threshold for the system to stop blowing cold.
Now you could just recharge with R-134a, but let's be honest, that shit just sucks. It's 30% less efficient than the old (and now banned, thanks EPA) R-12. This means your A/C won't blow as cold, and has to work harder.
But, you say, isn't R-134a my only option? Oh no, no, no!
There is another option. A little thing called R-12a. It's a hydrocarbon blended refrigerant. No license is required, and it's legal per the EPA. (If you have an existing R-134a system, it's legal to convert it to R-12a.)
What is a "hydrocarbon blended refrigerant" you might ask? Well, I'm not going to sugar coat this: It's propane.
Now, this isn't the same propane you use to burn steaks or heat your home with. Unlike Hank Hill's propane, this stuff has gone through extra refining to remove stuff like methane. We call this refrigerant grade propane.
The most popular version of this for cars is sold under the name Duracool R-12a.
It's sold in 6oz cans and 30lb cylinders.
To recharge the system in our GTIs, we'll need exactly 7.4oz, or 210g.
"Hold on a second," you're saying, "the sticker under my hood says 525g!"
Yes, that's for R-134a, but R-12a is 40% more efficient, this means you need 40% less!
So you'll need two cans. You can pick it up on eBay, it runs about $10 a can.
At this point, I think you're still stuck on the fact that we're going to be pumping propane into our A/C system, so let's go over some safety facts!
Duracool has an auto ignition of 1635°F, which is actually higher than the auto ignition of R134a (1328°F).
Also, you need to take into account that your car has 75 pounds of highly flammable gasoline, a sump full of oil and a 1 gallon tank full of methanol. I think 7.2 ounces of propane is the least of our worries.
Okay, now that we've got that out of the way, let's get to some data points!
R-134a Data
Ambient Temperature: 70°F
Compressor Load: 12Nm
Vent Temperature: 64°F
Condensor Temperature: 40°F
R-12a Data
Ambient Temperature: 70°F
Compressor Load: 7Nm
Vent Temperature: 46°F
Condensor Temperature: 30°F
Look at the change in compressor load; that's almost 40% more efficient! This translates to colder air and improved gas milage; plus less wear on the compressor and related parts.
The conversion to R-12a requires no parts to be swapped out. It uses existing R-134a fittings. All you have to do is evacuate the existing system, pull a 30inHg vacuum, then charge the low side with liquid R-12a (invert the can while charging).
It's best to charge by weight, so go ahead and put a full 6oz can in, then use a small postal or food scale to charge an additional 1.4oz.
That's all there is to it!
Hopefully this thread has been an informative introduction to hydrocarbon based refrigerants. If you have any questions, I'd be more than happy to answer them.
The compressors are inefficient and prone to flat out blowing up.
The evaporators are small, the cooling fans smaller and to top it off it has to put up with heat soak from the radiator and intercooler.
What to do? Well, if your A/C isn't blowing cold, you might need a recharge. Systems lose refrigerant naturally over time. With the seals on our compressors, you could lose up to 25 grams over 3 years. That's about the threshold for the system to stop blowing cold.
Now you could just recharge with R-134a, but let's be honest, that shit just sucks. It's 30% less efficient than the old (and now banned, thanks EPA) R-12. This means your A/C won't blow as cold, and has to work harder.
But, you say, isn't R-134a my only option? Oh no, no, no!
There is another option. A little thing called R-12a. It's a hydrocarbon blended refrigerant. No license is required, and it's legal per the EPA. (If you have an existing R-134a system, it's legal to convert it to R-12a.)
What is a "hydrocarbon blended refrigerant" you might ask? Well, I'm not going to sugar coat this: It's propane.
Now, this isn't the same propane you use to burn steaks or heat your home with. Unlike Hank Hill's propane, this stuff has gone through extra refining to remove stuff like methane. We call this refrigerant grade propane.
The most popular version of this for cars is sold under the name Duracool R-12a.
It's sold in 6oz cans and 30lb cylinders.
To recharge the system in our GTIs, we'll need exactly 7.4oz, or 210g.
"Hold on a second," you're saying, "the sticker under my hood says 525g!"
Yes, that's for R-134a, but R-12a is 40% more efficient, this means you need 40% less!
So you'll need two cans. You can pick it up on eBay, it runs about $10 a can.
At this point, I think you're still stuck on the fact that we're going to be pumping propane into our A/C system, so let's go over some safety facts!
What is the difference between regular propane and the refrigerant propane that is used to manufacture the DURACOOL® products?
The propane that is regularly used for barbecues, and general consumer or commercial use is a by product or deritive of the hydrocarbon manufacturing process (the production and refining of raw oil products). The propane used for standard applications (such as your home barbecue). In order to utilize the product as "refrigerant grade" the product is further refined to render out methane gases and other impurities. This refrigerant propane is different in many ways, most notably is the disparity in the auto ignition. Essentially this refining makes the product safer and more stable. The Auto ignition for regular grade propane is ~842 F., while the DURACOOL® products auto ignition is ~1635 F.
Why does DURACOOL® have the scent of propane?
The additive "ethyl mercaptin" is actually a stenching agent that is added for safety reasons. Mercaptan, as it is commonly known, is added to natural gas, propane, butane and virtually all gases as an agent that will alert the user to any leakage. The addition of mercapan should be viewed as a safety feature (see below). Mercaptan is also condensable in the AC system and can not limit performance in any way and will not negatively impact components. The mercaptan smell is not detectable under regular working conditions or under normal install conditions.
Have there been studies to determine the potential level of incidence, in terms of ignited automobile compartment leakage?
Internationally respected risk assessors Arthur D. Little, in a detailed UK-based study, estimated the risk of an ignited refrigerant leak in the passenger compartment of a motor vehicle as being in the area of 3 in 10 million. Their findings, from a local perspective, mean that if every car in the USA (some 50 to 60 million vehicles) were to use a hydrocarbon refrigerant such an accident might occur once in every 50 years.
What would the impact of and "incident level, once every 50 years" ignited automobile compartment leakage actually be?
In terms of the "impact", it is important to recognize that automobiles generally have 12-15 ounces of DURACOOL® refrigerant. If there were a full amount leak into an automobile compartment and it ignited, it would theoretically create a "flash" which would last 1-1.5 seconds.
There are eminent Risk Assessment Reports available which document the safety of hydrocarbon refrigerants in motor vehicle air conditioning systems.
Duracool has an auto ignition of 1635°F, which is actually higher than the auto ignition of R134a (1328°F).
Also, you need to take into account that your car has 75 pounds of highly flammable gasoline, a sump full of oil and a 1 gallon tank full of methanol. I think 7.2 ounces of propane is the least of our worries.
Okay, now that we've got that out of the way, let's get to some data points!
R-134a Data
Ambient Temperature: 70°F
Compressor Load: 12Nm
Vent Temperature: 64°F
Condensor Temperature: 40°F
R-12a Data
Ambient Temperature: 70°F
Compressor Load: 7Nm
Vent Temperature: 46°F
Condensor Temperature: 30°F
Look at the change in compressor load; that's almost 40% more efficient! This translates to colder air and improved gas milage; plus less wear on the compressor and related parts.
The conversion to R-12a requires no parts to be swapped out. It uses existing R-134a fittings. All you have to do is evacuate the existing system, pull a 30inHg vacuum, then charge the low side with liquid R-12a (invert the can while charging).
It's best to charge by weight, so go ahead and put a full 6oz can in, then use a small postal or food scale to charge an additional 1.4oz.
That's all there is to it!
Hopefully this thread has been an informative introduction to hydrocarbon based refrigerants. If you have any questions, I'd be more than happy to answer them.
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