R53 AC Compressor won't kick on
 

Hey all,
Having an issue with my auction R53. Everythings been great except for the summer heat. Recently had the AC recharged (by a shop not myself) but realized the compressor isn't engaging. Fuse is good, swapped relay so that's good. I went ahead and jumped the relay to give direct power to the compressor and it kicked on immediately. Any thoughts on what this could be?

Maybe vacuum pressure is dead? The cars had electrical issues so my thought is maybe a bad wire that way.

The compressor needs a minimum freon pressure to kick in.
I'd go back to the A/C shop & ask them to check the pressure & for leaks, or get a DIY re-charge can & see if that's enough to fix it.

The R52/53 AC compressor clutch uses a ground from the clutch through the compressor to the engine ground unlike the R56 and up that has a ground wire on the clutch.

you could have corrosion between the clutch and compressor. If you ohm out the clutch from the wire to the engine ground and you have more than 10 ohms, you have corrosion.

You can take it off and clean it and it’ll work fine if you get the ohms below 10.

check the clutch same happen to me before , the ac comp. have like an actuator that its call it clutch

I dont think its the clutch as I was able to get it to engage by removing the relay and putting direct power instead. The compressor immediately spun up when I did this. So the only thing I can think of is that the relay isn't getting the signal it needs to power on, right?

If the clutch were an issue I dont think I'd be able to get it to engage at all?

What is your high and low Presure?

do you have gauges? Can get some cheap at harbor freight…

the AC button (on the control panel) will blink for error codes.

do you have the auto AC or standard AC option on your car?

Unfortunately I dont have a set of gauges, I can look into getting some this weekend / renting some from Advance.
I did a procedure I saw on here to get into the service mode for the AC, checked for errors and was all clear there. Ran a calibration for the hell of it but didnt fix it.
And its auto AC.

Yes gonna need more tools here…

inpa might help also. I have a thread on setting that up if your interested.

So I've got Inpa / Ista all those guys installed. Just looking to find the pressure it's reading from that switch (assuming it's analog)

Bumping this as I bought some gauges. Jumped the relay again to make it run. Ambient was 77 degrees , LP was going from 40-50 psi and HP was going from 200-250. That seems like too much pressure at that temp.

Is your blend door working? If not hot air is mixing in with your cold…

Bigger issue was clutch not automatically kicking on, only when I jumpered the relay. No successful updates yet. I replaced the pressure switch, still no go. Mini themselves evac'd and recharged the system for me, its holding pressure fine. They said they were getting weird voltage readings with diodes hooked up to the compressor. I refuse to believe its the compressor as it turns on every time I jump it.

Fuses 3, 5, 7 all have power at both sides. Checking Pin 13 (from X4010) it reads 13v no matter what. If I jump that wire, clutch engages and AC kicks on.
https://cimg3.ibsrv.net/gimg/www.nor...7248a35efc.png

I had a similar issue with my 04 R 53 a while back....turned out to be dirty push buttons inside the control head unit

Bryan

Did you say you have auto or standard AC option?

if auto, run the diagnostic and re- calibration from the control panel.

if standard you can test run diag from inpa

What year R53? I have a 02-04 HVAC controller that I don’t need. Going cheap to try it out. I have it on the for sale forum.

Found my issue. I replaced the BCM as mine was shot from water damage. Turns out the car I stole it from had standard ac, where as my car had automatic AC. Finally had a brainfart, and check the software, and low and behold I just had to enable the auto ac and disable the manual. Everything works great now.

Good find sir

Can a BCM be swapped out without needing to program it? I have two R53s with auto climate control that are a week apart on VIN dates and want to swap them to see if it solves my AC issues.

dump your module settings with ncsexpert

verify the new module has the same settings