Welp...so much for the A/C

[Josh]

confirm your fans are cycling when the ac is on. You will blow a hose in a matter of minutes if the fans are off and the ac is on.
The earlier cars did not come with a high pressure switch, like most cars have. The high pressure switch will shutoff the compressor before you blow a line. Worth looking into adding this.
It could be worse, could rupture the evaporator core - big job.

[David T]

The relief valve should pop before a hose but with old hoses the hose could "pop" before you pop the relief valve. If the fans don't come on you will "pop" the motor's head gaskets too so it is worth making sure the fans cycle properly. Part of a proper A/C service anyway, making sure the whole system functions properly. Often I see the fans cycle but they are cycling because the circuit breaker pops and resets. Not good. When the A/C is running the fans must run whenever the compressor clutch is engaged. Also check that BOTH fans are running, the fan blades are firmly attached the the motor shafts, and they are both turning in the correct direction. Make sure there is no license plate or anything else blocking the intake grill.

[Henrik]

The earlier cars did not come with a high pressure switch, like most cars have.

Exactly! This was the case for me and (IIRC) the first thing I added after I had purchased #1283 in 2005.

[TTait]

+1 for staying with R12.

To do a proper 134a conversion you really want to get all the old mineral oil out of the system if you can and replace with esther (good for R12 or 134a) or PAG (134a only)

This would entail draining as much oil as possible out of the compressor, and then preferably filling in with the new oil, manually rotating it for a minute or two minimum, and then draining all of that before reinstalling. Then before reconnecting it you want to remove the old accumulator, which you want to replace anyway, carefully remove the expansion valve, and then flush the entire system. you can buy flush from amazon etc. and either buy a flush gun cheap or rent a semi dodgy one free from the auto parts store. You never flush an accumulator, compressor, or orifice valve.

When you install new o rings be sure to clean the mating surfaces and threads on both sides meticulously, only handle the o rings with fresh perfectly clean gloves and then oil the o rings with the oil of your choice from above. you can also lightly oil the threads with the same oil but don't get the gloves dirty and transfer any contamination to the o rings or mating surfaces.

Aside from routing the hose through the frame as mentioned in many posts above, the only other gotcha's are:

Be super careful to to cross thread anything. most connections press together against the o ring, you get the fittings perfectly square and concentric, and then thread them in. Do not cross thread.

When you tighten anything you always use two wrenches. virtually every connection (except the compressor?) has two different sized fittings for wrenches. One remains stationary and the other is turned to tighten. Always put a wrench on the static fitting as well so nothing gets twisted or deformed.

R12 is available here and there on ebay and craigslist. It works best but its expensive. You can consider using Redtek 12, R12A, Or Johnsons Freeze 12 which can be found much cheaper, You have to watch pressure (and sometimes flamability)but I believe they all work better than R12A. If you do switch to 134a you may need to adjust your low pressure cycling switch to get adequate performance. I've read in other applications that you can turn the adjusting screw between the terminals on some low pressure switches counterclockwise to lower the cycle off pressure down to 21psi to get better performance on 134a (see page 8 here https://www.originalair.com/download...ons/15-211.pdf).

If you can run an R12 substitute for a year, but you feel like you really need the system to run a little colder, you could have the substitute pumped out down to vacuum again and install real R12 with some confidence that it wont likely leak out. If however you run an R12 substitute for a year and you are satisfied with its results, keep running it.

So:

• if you flush the system then any contaminates will be cleaned out.
• If you install Esther oil (and go ahead and add the UV dye too) then you can run virtually an refrigerant in the future.
• If you need COLD air got for an R12 substitute for the first summer and see if it makes you happy. If it does leak out its much easier on the environment than real R12 and it cools better than 134a.
• If after a summer with R12 substitute you really want to put in Real R12, you can still do that to.
• At any point if the system is working to any beyond you needs and you find a need to switch to 134a for some reason - you can do it easily if you used esther/Synthetic esther
• If you use esther with a UV dye, if you do develop a leak it will be easier to find with a $15 kit of a UV flashlight and yellow glasses.
• If your going to own a DeLorean, you may as well buy the hose and manifold set for R12, and a vacuum pump, a flush gun can be nice to have too if you are ever going to work on an AC system again.