TIMM'S BMW E31 AIR CONDITIONING RE-GAS

I've re-gassed loads of cars now using the method shown here:

 

However, on the E31 the compressor-clutch is not cutting-in, this one is going to take more than just gas! There is a possibility that there is a massive leak somewhere, but I'm not put off. I'm going to fill the system with all sorts of stuff this time just in case.

I start off with some leak-stopper, give it a damn good shake. turn the tap fully anti-clockwise, fit the can to the fitting and fit the other end of the pipe to the low-pressure connector on the A/C system:



Fire the engine up, switch the A/C ON at low speed. Now screw the tap fully into the can and then slowly unscrew again, this will let the leak-stopper into the system. Keep an eye on the pressure gauge to make sure the safe pressure is never exceeded. Heat up the can in a bucket of hot water to make sure all the stuff is expelled from the can. Screw the tap fully in again and remove the fitting from the A/C connector.



Open the tap to expel any charge left in the can (be careful, red-stuff might come out). Remove the can from the fitting and then do exactly the same with the Pag-oil. Always make sure the safe pressure is not exceeded. I was glad to see that the compressor-clutch has now kicked-in and the A/C system is sounding OK. The auxiliary-fan has also started, this is great news as it means that there is not a massive leak and the system was just a little short of gas.

Now it is time to re-gas, I've got three cans of the stuff just in case. When re-gassing make sure you open the tap slowly. Don't be fooled by the gauge quickly reaching the green area, this is just the back-pressure of the gas passing the pressure-fitting that is fitted to the A/C system. The plan is to keep the pressure out of the yellow area while the gas is going in. Here is the first can going in:



The can needs warming up as it will quickly reach freezing point and your hand will get stuck to it. Keep closing the tap and seeing if the pressure stays up, normally it will decrease and more gas is needed. Here is the second can going in, the tap is closed and the pressure has stabilised....we're done!



I still had some gas left in the second can, so I opened the tap with the other end disconnected until it stopped hissing. Even with the other end disconnected you will notice that when the tap is opened the pressure gauge will move just short of the yellow area. This is why you have to take it easy when re-gassing to ensure the correct pressure is reached.

Result? Ice-cold air, the E31 can really bung out some air, much less refined compared to the 7-Series!