It is starting to get warm outside and I am ready to fix the A/C on my 1976. It has factory A/C and every part in the A/C system is original. The compressor runs fine, but the good old R-12 leaked out long ago throughout its long life in storage.

My question is to those of you who have converted over to R134...are you happy with it? If so, what additional recommendations do you have?

I plan on replacing all the seals, installing and new dryer, and whatever else it may need to fix all the leaks. I also am considering adding a pusher fan if I do convert it over.

I know that R 12 is still available (but expensive) and I am wondering if I should seal up the system and keep the original freon in it or go ahead and convert it to the new and much cheaper R134a. (Also, has anyone ever tried the compatible R-12 replacement coolant?)

 

I haven't done this but I do know a thing or 2 about conversions. You will need a new rcvr/dryer, hoses (old ones won't work) replace the oil with PAG, add adapters to the old schrader valves for R-134a, and probably add a hi pressure switch, and possibly replace the metering device and low pressure switch if they are bad. As just a thought you may want to go to a competant shop who does A/C and at the very least have them do a vacuum test to see if you have any leaks, the condensor being exposed in the front of the truck is easily damaged. If I remember correctly R-134a is about $4 a lb, and R-12 is $35. If it was me I would consider buying a kit from vintage air, last time I checked the whole kit was about $900 and you have to get it charged someplace, seems like alot but it's guaranteed to work. I would not recommend using some replacement or blend refrigerants ever! Usually retrofit performance is about 3 deg warmer than the old R-12.

Hopefully somebody will come along who has done this project, good luck.

 

Hey check out the A/C forum

 

i have done my share of ac work, not on automotive but agricultural use. I would do a vacuum leak test, then if put on some R-134 adapters, replace the receiver/dryer and charge it up. If all of the R12 has already leaked out then you probably don't have to worry about blending. Just my $.02, but freon is freon, and if your compressor is good it will pump it through the system.

 

For doing a conversion:
The hoses can be rebuilt at about $30.00 a hose, if you can find the right place. There is conflicting information on whether this has to be done or not... I have read both... but by the age of you hoses it sure wouldn't hurt to go to vapor-barrier.
The entire system must be flushed with solvent...mineral oil and 134 don't go together. pick your poison. Mineral spirits seem to be the choice but I like to follow with brake cleaner to remove any residue.
The compressor will be full of mineral oil, I guess one could clean it, but I have never tried. Rebuilts are about $90.00.
Change the expansion valve.
It is virtually impossible to overtighten the larger fittings.... really put the muscle to them on re-assembly.
R-134 is marginal, IM0, (have a 78 converted), the system just was't designed for this lousy replacement. (no I am not happy, but am marginally comfortable) A pusher will help but I can't fiqure out how to fit one in between the grill and condensor. A larger condensor would be the ticket but I haven't found one, let me know it you do.
Watch the high side with 134... get over about 250 PSI and the clutch can't take it.

Part list & Cost: (estimated from memory)
Hoses: 75
Valve, expansion: 25
Insulating tape 24": 2
Dryer: 30?
Service adaptors: $15 (get Right angle ones, with steel bodies if you can)
Gas: $20
Compressor: $100
oil: $15?
O-rings: mostly included: $5.00
Cleaners: $10.00
So around $300.00 provided your condensor or evaporator is not shot.

borrow guages and a vacuum pump

Freeze 12 is a little better than 134 and not as good a 12, in the one truck I used it in, with no problems after 2 years. I would be very surprised if your compressor still seals around the shaft after 26 years.

GL

 

Thanks for all the advice so far. I am really debating on what to do. My truck is in very original condition, so I do not want to put any aftermarket A/C systems in it. (However, I would consider it on a different vehicle.) Like many of you have, I have heard just about every conflicting way to go about this. I spent $1200 (in parts only...I did the labor) on converting/overhauling the A/C sytem on my 64 Buick and it cooled great...for 5 months and then the NEW seal in the compressor blew out again. The opposite extreme, I threw three cans of R134a in a 84 Buick beater car (with no efforts of conversion at all, and I didn't even evacuate the system) before I sold it two years ago and the guy said it still cools great. So who knows?!? I just want to hear from you guys with the factory original A/C systems in your truck to tell me what works the best.

 

Just a word of advice, some of the aftermarket freon stuff is very flammable. So it would be to your best bet to stick with R134a.