a somewhat popular and convenient thing to do on 4x4s, especially old vehicles, is to remove most everything in the a/c system except for the compressor and mount a small air tank somewhere on board, usually in the backseat area or bed of the vehicle, but sometimes under the hood on the inner fender since old V8 powered vehicles could house a family of four under there usually. custom lines would be fabbed up to route compressed air to the air tank. after that, inflating and deflating tires would be a breeze, along with other uses for compressed air.
i had an idea to get this to work somehow on my accord. just for fun. i'm not really going for performance on this car as much as functionality and versatility. having on board compressed air would be great for so many things. especially for performing any sort of work where air tools could be used. my problem is this...
an a/c system like the system in these accords is an R12 system. the compressor is lubricated by POE oil that is designed to mix with refridgerant. since i won't be using refridgerant, i won't have lubrication for the compressor. old compressors on the 4x4 vehicles that convert an a/c compressor to an air compressor have a seperate oiling system that doesn't incorperate the refridgerant. its almost like they have an oil pan, and the crank in the compressor picks up oil and slings it around, not unlike most internal combustion engines. the fact is, those old compressors are very similar to gas engines, except they are belt driven, so they don't use fuel. not only is this the problem, but i'm not sure what sort of air pressures i would get from an a/c compressor compressing ambient air. R12 vaporizes at roughly 15 degrees F. ambient temp has a significant effect on its pressure. a typical R12 a/c system has a high side pressure of anywhere between 180 psi and 220 psi. these pressures would be perfect for running air tools, however, ambient air pressure is far less affected by its temperature. meaning the compressed air leaving the compressor will be far below that of an R12 system.
i'd like to find an old a/c compressor that has a seperate oiling system and see how hard it would be to fit into the accord's engine bay. of course, a new mounting bracket will have to be made more than likely, and a new a/c belt will have to be used, and the size of that belt will depend on the compressor used. the a/c button on the dash will still engage the clutch on the compressor. the compressor will compress air and send it to the air tank, which would have a purge valve to release air once it reached a certain pressure to avoid mishaps. safety cut-out switches from the original R12 system could be utilized to keep components safe. the air tank would more than likely have to be mounted in the trunk of the accord. when i need to use compressed air, i'll just hook up an air hose to the tank and do my thing, so long as the engine is running.
the biggest issue here is determining what sort of pressures i could expect from this. i would need atleast 160 psi i think to operate an impact gun. at that pressure, i wouldn't be able to use the gun for more than maybe 5-8 seconds at a time without letting pressure build back up, but that would be fine with me because you don't typically need to run an impact gun for more than a few seconds at a time anyway. if the pressures are just enough to inflate tires and not enough to run an air gun or paint gun or whatever else i'd want it for, i would most likely scrap the idea and move on. inflating tires isn't fun enough to make the project worthwhile. and if it won't work and the only way to have on-board compressed air is to buy an actual air compressor and mount it in the trunk, i'll reject that idea too, cause thats too costly, and i'd need extra fuel or 110 V electricity for that and a way to vent exhaust gas out of the vehicle's cabin, and i'm not down with that.
if someone can determine how much pressure this idea is capable of, or if someone knows of a way to build pressure to a usable amount, please chime in.
