Airco upgrade - questions

[Remco]

My airco is not working at all, i bought the car a few weeks ago and after some more urgent issues now it is the turn of the AC. When switching it with the controls to where it should start cooling i can hear the revs go down. Also does the blower work. Just no cool air. I learnt that the oem compressor is not good, i should change to a Sanden. I learnt for that that i need an adapter which i found together with the aluminium support from an E28 which i found as well. As from here, my questions. I am quite experienced on working on cars, engines, etc. but i don't have any experience with AC. Who could give me step by step instructions for how to proceed? What else should i change, what can i keep. Assuming the actual system is empty, can just start dismantling? What compressor would be the simplest? Thanks!

[Mike W.]

I disagree on the compressor, the stock swashplate, assuming that's what you have, is quite good. Quiet, smooth and long lasting. But it doesn't like to be overcharged, that can cause failure.

Most likely your system is out of refrigerant. Hoses are highly suspect, especially if you have any of the red cloth ones, but after 45 years anything and everything is suspect. The condenser sitting out front is at risk of damage. First step would be to pressurize it with air to find any obvious leaks, and repair them. Next it gets more complicated. Making hoses isn't terribly complicated or difficult as long as you can find A/C barrier hose. I don't know where you're at, but if you recharge it with R134a, performance won't be particularly good. There are other options, but it can get complicated.

[Remco]

I am in France... I am not afraid for complications as long as I can get it to work well. I guess I better find a good place that is specialized in working on AC´s and see how negative they are.

[Mike W.]

I didn't like my first reply so here we go again.

If you want to do it yourself I would go in the following order, and it assumes factory A/C, I know in Europe aftermarket systems were popular, but we never saw them here..

Pressure test with air, run it up to 100PSI, er, 7 Bar or whatever, as much as you can. If no obvious leaks I would replace any of the red, fabric covered hoses, they like to leak, they get porous. I've made my own before using one size larger A/C hose. Or you can buy them or have them made. Then fill with air again and leak check, leave it pressurized for a while. The hot compressed air will probably contract a little bit, then hopefully it will be stable overnight.

If it holds, you can then try to evacuate the system and charge it. Guessing you will only have R134a to work with, which doesn't do a particularly good job on these systems originally designed for R12. The compressor should be up to the task, but if you want decent A/C, you will need an improved condenser, a parallel flow type. Also, the auxiliary fan is an absolutely essential part of a working A/C system on these cars.

Automotive A/C on these cars isn't very complicated, any decent shop should have no problems figuring it out.

[528i-1981]

Salut Remco,

I found the Hack Mechanic book "Just Needs a Recharge" VERY helpful when I renovated my A/C system. As Mike said, the system is straightforward. You'll spend most of your time figuring out fittings and hoses and then chasing leaks. It's available on Amazon.fr.

[Remco]

I bought the book... so I got it to work, then without knowing the fan did not work anymore, the diode died I found out later, pressure went sky high and a hose blew. Back to start... I changed the hose, changed the dryer again. Added the oil (yes, the correct type) and charged again with about 850g r134. It worked quite good for quite a while but the compressor started to make very odd noises. So, I guess the interior of the compressor is about to die... I did not turn it back on. Now I am considering what to do. Buy a used original compressor (300€ or more) and hope and pray it will last. Or, buy the adapter, a new Sanden and make hoses. By the way, I do not have clear if for a Sanden I need side exit or rear exit. Somebody knows? What is your vision? For me it cooled enough with all standard and r134 but what should I do? I don't want to change condenser, fan, etc. unless it stops working or leaks.

[Theotherotter]

When I spoke to AC Solutions here in the US about restring functioning AC to my E12, they indicated that you could use either a side-exit or a rear-exit Sanden according to desired routing. This assumes that new lines are being made.