'90 760GLE ECC (aircon); minor prob?

[TheJoyOfSix]

> and a thing
>that seems to be popping up every morning between the
>showers.
>

>Chris aka Gerry the Gerbil

That 'thing' wouldn't be a kind of orange/yellow circle would it? I've seen that too - anyone know what it is?
:P

[pettaw]

I've been looking into this into some detail, and have been on the American message boards about this. They've had A/C in their cars for a lot longer than we have and have much more experience.

Basically R12 which is the old refrigerant is a CFC and therefore illegal to buy and gas with in Europe, although you can still get it in America if you have special certification.

R134a is the new replacement, but its molecules are smaller, so it will find weak spots more easily, and it also runs at slightly higher pressures. Apparently the sub-standard cooling with R12 conversions is false, R134a can cool just as well if not better providing the refrigerant level is adjusted carefully and all the pressures and temperatures are carefully monitored whilst gassing.

The 'drop-in' replacements (R416a is the one they seem to use locally) are a blended refrigerant which consists of R134a plus butane/propane etc to help move the oil round the system because the R12 mineral oil is incompatible with R134a.

As far as the americans are concerned the blends are a way of getting your system working and then getting rid of the car cheaply, because it is a blend, the smaller molecules (butane/propane) will leak out first leaving you with R134a, which, being incompatible with the mineral oil in the system leaves the system underlubricated and can damage the compressor.

The proper way to do it is to convert to R134a, if your system is leak free its a reasonable propasition, if its not working its, to me a no-brainer, if you have to have the system opened, you might as well pay a small amount extra for the conversion.

The minimum required is to change the fittings for R134a, add a high pressure service port, if one isn't present and change the drier. Also recommended is to flush the oil out of the condensor, replace with a R134a compatible oil like an Ester, and then refill with R134a.

I was so dissatisfied with the service done on my system when the condensor went and I had it converted (no flushing done, hoses left untightened and the refrigerant leaking out, no measuring of the pressures when gassing etc etc ) that I'm currently in the process of getting a refrigerant machine and if necessary a C&G qualification so I can do my own work.

Sorry about the long post.

[andykem]

Look, whatever anybody else tells you, there IS now a lubricant (oil) that is OK to use in AC systems that run either R12 OR R134a. And, so far as I'm concerned, my 760's old R12 system having been gassed with R134a, using the R12/R134a oil, has worked brilliantly for the past month. And, it's certainly not 'hotter' than if it had been gassed with R12, so far as I can tell.

Albeit, my previous experience with R12 was with a 265GLE that didn't have an electric fan in front of the condenser. I understand that a fan can make a huge difference anyway to the performance of an AC syatem because of the cooling airflow thru the condenser. My 262C, charged with an earler 'drop-in' replacement for R12, proved a bit less than chilly in the last bit of 'blazing June', especially in traffic when not much air was moving thru the condenser on tick-over. But, maybe I just need to spend even more dosh on Volvo's cars, and get an R134a recharge?!

Cheers
Andy

[pettaw]

Yeah, the ester oil I talked about is the oil of choice because it IS compatible with the R12 and R134a. However, you should still flush out the old oil so that you can add back the correct amount. If you just evac and change the drier and then add oil then you'll be getting far too much oil which means you won't get optimum cooling.