Ac not working - high fan speed
 

So the issues with this truck just don’t stop. Want to sell it so badly but put so much money into it already. The stopped working this am. I checked that the Freon was a bit low and I topped it up a bit with 1 can of r134a. Now the ac doesn’t work at all an cold air blowing. Before at least there was some cold air just the other vents were blowing hot air. Now as soon as I turn on the ac the aux fan starts running at full speed and it’s blowing hot air inside the cabin. Any thoughts on what I could do ?

Did the aux fan run full speed before you added a can?
If not, you've likely overfilled the system. Earlier Bimmers used the AC's high side pressure to set the speed of the condenser fan.....higher pressure ==> higher fan speed. Not sure if E60/E70 does the same, but the pressure sensor is present so it's just a matter of configuring the IHKA/DME to crank up the fan speed as condenser pressure rises.

The aux fan was running perfectly fine before I filled it. It never really ran at full speed. What do you recommend I do now ? Should I try to release some of the r-134a I put in? I hope I didn’t damage the compressor because now I only get hot air.

I guess low Freon wasn’t really the issue but I’m still not sure why my ac wasn’t cold and why hot air was coming out of some of the other vents prior to when I added the extra Freon.

There are two things I dont mess with: Auto transmisson rebuilds and AC systems.


Becusae I dont have the right tools.


Go to a shop that will do a pump down and refill. There is a rather precise spec for freon. Might be $100-150?


Everything else with the AC- controls, sensors- all that I can do, but I just cant deal with the sealed system


Having said that, I know over-filling these can be an issue, but I cannot say that is what is causing your symptoms...

GL

I would put gages on the system and check the system pressures.

The full charge on an E53 (and I would think the E70 would be not much different)is one can so you likely overcharged it for starters. +1 on you probably shouldn't be messing with it.

The 4-zone in my '08 3.0si holds 1.54 +/-.02 lbs, (2) 12 oz cans.

+/- 0.02 lbs... thats 9 grams. Or +/- 1.3%

The e70 use variable compressor so they are more likely to fail in a way that is hard to diagnose.

You really need to measure the high and low pressure. Do you have gauges or access/rent?

I’m with you on this. Take it to Speedy, or the like for a full purge and recharge. The system only takes 1 lb of refrigerant if I recall, so a little high or a little low can screw it up. They can tell you how much it took after the purge, add oil and a dye as well, so you can keep track if you are worried about leaks.

Plus, the stuff sucks for the environment so a recovery by someone with the right tools best thing to do.