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Has anyone converted their R134a refrigerant to hydrocarbon refrigerant to improve mileage while using the A/C? Going throught the literature, use of A/C can reduce mileage by 15%, and use of the more efficient hydrocarbon refrigerant is about 30% gain in efficiency through lower head pressure and fewer cycling of the compressor. The conversion should improve your gas mileage by as much as 3mpg when using the A/C. Is their any testimonial out there on this type of conversion?

Don
2000 Silver Insight
57K miles
 

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I've never heard that R134a is less efficient than freon, but ok I'll go with this. I would simply stop right at that though personally for the simple reason that freeon is very expensive now as it hasn't been allowed to be produced in years. A small can that you would buy at an automotive parts store that used to be .99 cents now is worth about $25 last I saw any. People convert their older cars over to 134a because it's cheaper to convert them than to buy old R12

Ok so the conversion process from R12 to 134a is basically a different fitting and a different oil for the system. I guess maybe you could go backwards, but you'd likely have to make something custom go get it to work with the Insight. I'll personally stick with 134a, thats what the car was made to work with. In fact wasn't it legislation that forced car manufacturers to switch to 134a in the first place? Might be a legal issue with doing that.
 

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From a professional point of view ( I owned an auto repair facility for over 10 years specializing in drivabiltiy,A/C and electrical and have been in the automotive repair profession for well over 30 years) R134 is less efficiant than R12 by approximatly 20-30% depending on the original system.
To convert to a hydrocarbon based freon substitue (Frezon or Hot Shot which are about the only 2 substiutes approved for use in automotive systems currently) would not give you any advantage as the A/C system on the Insight as well as all other factory production autos is designed to work efficiently with that freon. When you perform a conversion of an older system from R12 to R134 it is not uncommon to see a drop in cooling perfomance, which can be off set with replacemnt of the condensor assemblyto a larger unit to dissipate th extra heat generated by the higher head pressures.
I have used both the mentioned substitutes and still feel uncomfortable using them as they are a "blend " refridgerant. In the event you should delevlop a small leak you should not just "top' of the system to attempt to get it cold again, as it is a blend it does not leak all the components out at the same rate when you just refill it without totally evacuatiing and recharging the system by just tooping it off it does not ever cool as well. Another aspect I don't care for is the flamability issue of a "hydrocarbon" blend. Think for a moment where the freon passes, in the engine compartment where a stong posabilty of ignition in the event of a leak could occure. Or worse yet and I have seen quite a few fail, the evaporator which is in the passengers compartment. Would not be a pretty sight to have it ignite there would it?
 
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