Improving the AC system's efficiency
 

It is a well known fact that running the AC system can drastically reduce gas mileage, so I did what I could when I replaced my AC compressor last year to improve its efficiency, and therefore reducing the amount of power it wastes while also improving performance.

The first thing I did was I tuned up the system the best I could. I removed and flushed the evaporator as well as all of the AC lines, I replaced all of the seals as well as the TXV and the filter dryer, and I insulated the low pressure AC lines before I reinstalled them to reduce the amount of heat they absorb from the engine compartment. The less heat the refrigerant absorbs, the less pressure the compressor will build and the less power it will take to run.

Then I turned my attention to the condenser. Since it was from 2005 and the car had over 220K miles on it at the time, the fins were bent beyond repair by flying debris. Even though the condenser didn't leak refrigerant, I replaced it with a new Denso condenser, which cost around $60 with shipping. In my opinion, replacing the condenser while the system was open was well worth the money to improve efficiency and prevent leaks in the future.

So once I reassembled the system, I evacuated it overnight with a vacuum pump to remove any air or moisture and I refilled it with 4 ounces of double end capped PAG oil, which apparently has better lubricating properties and isn't hydroscopic. I then added 19 ounces of pure R134A refrigerant, which is within the factory spec of 17.6 to 19.4 ounces.

After all of that work, the AC worked pretty good, I would say at least as good as when the car was new, although this car's AC never worked great, especially at idle.

But about 1 month later, I decided to try Envirosafe Industrial R134A replacement. It is basically a 60/40 blend of propane and isobutane, so it's a flammable refrigerant and I wouldn't suggest trying it.

So I took the car to a shop to have the refrigerant recovered, then I took the car home, evacuated the system for over an hour to remove any remaining R134A refrigerant, and filled the system with about 7 ounces of Envirosafe Industrial R134A replacement, which they told me is approximately equal to 19 ounces of R134A.

I immediately noticed that the system cooled off quicker, and it got colder at idle. Also, this refrigerant runs at a lower head pressure than R134A, so the AC compressor doesn't draw as much power to compress it. Not only will that improve gas mileage, but it should extend the life of the system too.

But as soon as I drove it on the highway, I noticed that the compressor cycled on and off more. With R134A it pretty much ran constantly on a hot day, but with this refrigerant it cycles on and off instead of running constantly, which should save some gas.

I also "feel" like the AC doesn't create as much drag while it is running with this refrigerant due to the lower head pressure, but I can't prove that.

Anyways, let me know what you think about this :)

It should be completely safe for people to try out. The auto ignition temperature of the gas is above 1200* F. Although the can itself should be stored below 125* F, but I think that is so the pressure does not build up too much in the can.

https://www.es-refrigerants.com/docs/13007_499.pdf

Edit: After reading some reviews from people who have used this product in their vehicles, most have said that it works better than R134a. An occasional HVAC person would say that nothing but regular 134a should be used, but I haven't read of anyone having issues with it. I think I might try this product in my vehicles now.

Thanks. It does seem to work better, it is better for the environment since it is ozone safe and it has almost no GWP, and it should be better for the system's longevity. But my biggest concern would be what would happen in a front end collision. If the condenser is smashed and wiring sparks or something... That could end badly. Or the less likely scenario where the evaporator goes bad and dumps all of the refrigerant inside the car. A spark from a relay or switch could also end very badly.

I remember reading a forum where someone apparently used this refrigerant in their car to replace R12 (IIRC an old Porsche) and somehow a hose was sliced by the cooling fan, I think while they were running the car on a dyno. It supposedly ended up starting a fire. I wish I could find that forum.

EDIT: This wasn't the forum I was looking for, but here is an article about the incident: http://www.imcool.com/articles/airco...erant_Fire.htm

I think if you keep your vehicle well maintained you have little to worry about. In the event of a front end collision... Keep a fire extinguisher handy in your car if you're worried about it :)

Edit: I think I have little to worry about because my evaporator is located in the rear of my engine bay and I am planning on buying a heavy duty front bumper. As far as that isolated incident goes... I suppose if your AC hoses run near any fans then this idea poses a few risks.

I don't think it is that much of a risk either, but I am not going to say that everyone should start using it and that there is no risk at all either because that's not the case at all. According to the article above, a guy apparently almost lost his car because of a fire due to the use of this refrigerant.

May I ask what precisely you are doing about the mass of extremely reactive hydrocarbons at the rear of the vehicle?

If you carry a 2pound fire extinguisher you should be good.

Not a good comparison IMO. The fuel tank and lines are well protected and would be much harder to damage than the AC condenser, which can easily be damaged in a 5 MPH crash or by flying debris as I know first hand. If the back of the car is hit hard enough to damage the fuel tank, you would have bigger problems than spilled fuel.

Also, the AC system runs at much higher pressures. The fuel system usually runs at about 50 PSI maximum (although some systems run at a higher pressure), but the AC system’s high side can easily exceed 300 PSI on a hot day.

Not much to worry about. In reality, you have 7 ounces of "fuel" in the system. Even if it burned or exploded. What is the likelihood of damage from 7 ounces of fuel burning? If it even combusted at all...

If my car didn't use special refrigerant I would do this for sure.

Thanks for the input! I am not very worried about it either, but I wanted to discuss the possible risks as well. I guess my biggest concern would be if the condenser or a refrigerant line was punctured or damaged and the escaping refrigerant ignited, the resulting blowtorch could ignite surrounding combustible materials.

Since it is the industry I work in, consider natural gas leaks. It is not very often they ignite, many go entirely unnoticed for years. Particularly on small leaks, the gas would dissipate so quickly to a percentage where it is no longer a threat.