Questions about A/C

Ive got two air conditioners for a 2nd gen ram 50/mightymax. one is a mitsubishi system and the other is a mixture of american made components from chrysler and others. so far im leaning towards using the mitsubishi made system since it appears to be more thought out and integrated to the truck but i did notice that the dealer add on one seems to use more off the shelf parts like the expansion valve, eccs (electronic clutch cycling switch), and the sanden sd508 compressor which might give me better options for which refrigerant i charge it with. one of my biggest questions is what refrigerant should i try to use? obviously R12 would be ideal since thats what they were designed to use but i hear its expensive and rare and i live in a small area so there may not even be anyone who deals with it locally. all of the R12 substitutes seem to be on the way to being phased out and R134a from what i hear isn't as efficient as R12 and all of the seals need to be changed out (no biggie since most of the system is not installed) i guess i will need to see what the local ac shops say but i wanted to get some input here first to see if anyone has some advice since im totaly new to ac.

If you use the Sanden SD-508 the manufacturer states that it is rated for R12 refrigerant use. I think you're really going to struggle finding anyone who can get their hands on R12. I googled refrigerants and an alternative came up - propane. It is way cheaper, easily available and is actually safer than refrigerants (environmentally and personally) and is less likely to leak past seals like R22 plus if R22 ignites the subsequent gas that is given off is LETHAL. If the system is evacuated properly and charged it should work...really well. But there are all sorts of debates on using propane - what type (fuel or refrigerant), will it damage the compressor windings, are you going to blow up an entire city in a Hiroshima-type explosion etc even if propane is being used commercially as a refrigerant (and as fuel for forklifts used in enclosed spaces)

Thanks for the reply geezer101 i have heard of people using propane and isobutane in a 79/21 mixture with great results. my only problem is that i doubt i will be able to get anyone to charge it with it and if i do it myself i will have to buy all of the equipment to do so and learn how to mix them together myself (if i dont use straight propane that is). i was wondering if these systems preform ok with an R134a conversion and whether or not they are able to hold a charge since i hear sometimes older hoses designed for r12 will leak out the smaller molecule R134a.

That's the pitfall of A/C is ensuring the system is sealed. My truck had the SD-508 compressor fitted but I went through my stockpile of spares and discovered I had a newer Nippon Denso compressor and cradle off another 4G6X engine that bolted straight up to my 4G63. It's smaller, lighter and more efficient. I have to get someone to modify the hoses as the connections are different but I really need A/C as I live in a city that is 0.3C short of the hottest capital on the planet. By the time you buy all the crap to charge the system and find a source to supply the oil and gas you are already handing over the same amount of cash for a shop to do it. Not a good investment for a job you'll only do once in a few years if you're lucky. Ask around, you might get lucky and find someone who is using propane mix (maybe even a truck refrigeration shop is worth a try...)

I take it you must have the dealer add on system since you used the sd508 compressor? i wonder if the mitsubishi one uses different seals that are more R134a happy? i will definitely ask around about propane though.

I just found out about a refrigerant called R152A and it looks very promising. the best part is is that it is just duster spray and can be bought anywhere. has anyone heard of this? there is a video on youtube of someone putting it in a mid 80's buick with great results

Seen similar videos. Difluoroethane. There are a number of videos where guys have successfully charged their A/C with it. Another alternative but you may still have issues finding someone who'll use it to regas your truck.

True im starting to wonder if anyone in my area will even want to deal with my truck being that its from 87' ive already taken it in to a few mechanics that wont even touch it. i do know of one guy who might though and i will have to get a hold of him. I also just realized im missing the alternator bracket and bolt and the 3 bolts that bolt the bracket to the block so i will need to get those before i can finish the install. if anyone has some i would be interested.

Yes my truck had the A/C added at the dealership. A/C in my model is rare here in Oz which was one of the reasons why I bought it even though the truck had a pretty rough life. Air con is never 'cheap' to repair or service but it's worth it once it's working properly. I would think most shops would jump at the chance to fix your A/C - it's so much easier to work on than a FWD and the engine bay is relatively open.

what is your system charged with if you don't mind me asking? I bet you have a much better selection of gasses there than we do here.

My system is currently charged with 70% nitrogen lol. The system was disconnected when I bought the truck as the engine had been pulled and dumped on a shipping pallet. So I'm up for $200+ AU to custom fabricate the lines to mate the ND compressor to the old connections and another $200 to charge/test it - add another $40-50 for a replacement dryer and viola! I'm freaking broke...

to use r-134a in a truck with r-12 there are a few things you need to do, and a few you can do but not necessary. You need to change out the expansion valve for one that is for 143a - the orifice size is different for the different gasses. You must change out the drier, as it has been exposed to air and full of moisture. You should flush the system to clean out any dirt, and contaminated oil in the system. You must use ester oil to top off the system - the Pag oil used in r-134a systems will destroy the system if it comes in contact with the r-12 mineral oil. Depending on your system, you may have o rings on the fittings, change them for 134a rings. Get the adaptor fittings for the ports on the system. DO NOT use propane or propane / butane mix - a fire under the hood will become a blowtorch when the lines fail. Many r-12 replacements were pulled because they were propane or propane mix. You will also need the outer pulley on the crank for the compressor - it was an add on for the truck, standard on the starquest crank pulleys. Don't forget the belt tensioner for the A/C belt on the upper left of the head facing the motor (exhaust side). Hope that gets you started.

thanks for the reply pennyman1. im thinking i will probably try R152a first seeing the success others have been having but if not i will do all of those things you mentioned. if i go with R134a however i will probably use the dealer add on system since R134a expansion valves are cheap and the system i pulled is missing it anyway plus if that sanden SD508 is unhappy with R134a i bet finding a drop in one that will would be easy since it seems to be a widely used modular compressor. either way ill be left with an extra system once im done.just for curiosity would this be something that would be wanted by someone here on the forum?