I recently bought 1 '66 F85 that has factory A/C. The car was siting in dry storage for the last 20 years and only driven briefly to keep everything moving. Last night I checked out the A/C system to see what condition it was in. I attached some r134 converter connections to the high and low side and used my r134 gauges to check the pressures. They both read about 50 psi. The compressor does not come on when I switch to A/C. Is it worth trying to recharge with r12 or would it make better sense to have the remaining r12 drained and do a r134a conversion? Does anyone know how much it costs to have the old r12 reclaimed?

 

Welcome.
Post pictures of your car so we can all drool over it.
I say convert it. I have had several R12 systems done. I have had some flushed and changed the receiver and did everything that was recommended. On some others all they did was pull a vaccum, put in some oil and the 134 stuff. The changeover worked great on all the systems, no matter how much or how little work was done. I have heard people say the 134 isn't as cold as the 12, but I do not agree. The one vehicle I kept for a long time was a 94 Chevy truck (13 years) the air conditioner would freeze you out! It worked very well.

Good luck,
Mike

 

When you say compressor does not come on, do you mean the clutch doesn't engage or it's locked up? There's nothing in a 66 A/C system to prevent the system starting from low refrigerant pressure. You might want to check with a set of accurate R12 gages though.

I'm in a minority here, but if the system's not leaking and you can get R12 that's what I'd put in it. You can get a POA valve cal'd for 134a and also a POA eliminator kit that converts it to a cycling clutch system, but I'm not too crazy about subjecting a big A6 compressor to cycling duty.

If you're going to convert, I'm told there's a kit available to mount a Sanden compressor in the Olds bracketry. That, a POA eliminator, and a new larger condenser will enable the system to use 134a.

 

If I slide the switch to air or recirc, the compressor does not engage. I remember that when I first got the car and I was trying to turn the vent on, I pushed it past vent all the way to recirc and I heard the engine slow down and stall. It's possible it may have engaged that time, but it does not now. I got a better set of gauges and not I see there is very little pressure left in the system, about 20 psi. I have a a/c vacuum machine and a gauge set with service port so my plan was to replace the drier, draw a vacuum, ensure no leaks then refill with r134, ester oil and UV dye and hope it works. I've read that the POA valve can be adjusted so I may look into that as well.

 

The thing is, R12 can be a bit difficult and expensive to get, but it IS available, and if you've got a fairly original car with pressure in the system, there's a good chance it might work if you just put in a bit more R12, and you wouldn't need to do anything else to it.
Check to see if the compressor can be rotated by hand (shouldn't be difficult to turn), then put 12v to the clutch contacts and see if one fitting gets colder and the other gets warmer. The engine slowing down and stalling might mean that the compressor is tight and about to seize, which would help make you decision for you.

If the compressor seems okay, I'd poke around and see if you can turn up some genuine R12 (sealed cans, or somebody you trust) and try refilling it, and see what happens - it might be cheaper than the modifications you're planning to make. The only problem is that if it doesn't work, you may be out that money, unless you can reclaim the R12 and re-use it after you fix the problem.

Also, all of these systems are leaky - loss of a pound a year was considered normal, and replacement in the spring was part of routine maintenance, so if you do get it to work with R12, you'll need to add some from time to time (not too much, though, if you've still got pressure after 20 years). R134 is a smaller molecule, though, so it will leak evan faster out of any given system (R134 systems use hoses with a special layer to cut down on leakage through the rubber), so if you convert, you'll be pouring 134 in every year, too.

Good luck!

- Eric