AC not coming on? No issues with heat.....

[Fffrank]

2002 M3 -- The HVAC controls all work fine except that the AC button doesn't light up (or blow cold air.) I've checked fuses #28 and #63 and they are both good. Blower motors work fine.

Only other symptom is that climate control seems to reboot itself every few minutes. Maybe it's trying to reset the AC or maybe it's fubar'd?

Doesn't seem like any other IKHA failure that I've seen posted but does anyone have any other ideas how I can diag?

[DropTopKingM3]

Do you have a friend with an e46? Even if its a non-m. Try installing a different HVAC control and see what happens.

[Lukem3]

Check freon pressures. If freon is too low the pressure switch will trigger and not allow u to turn the ac on. Also could be a faulty coolant sensor but most likely you need a charge or there's a leak somewhere

Sent from my SM-G955U1 using Tapatalk

[Fffrank]

Pressure switch is showing 2.3bar in INPA which tells me that it's working and has 33psi which should be enough to get the compressor to turn on. I can't measure any high-side because the compressor isn't starting at all (all the other threads I can find, the compressor at least runs but the system blows hot air -- I'm not even getting an electrical signal from the IHKA it seems like.)

INPA is showing correct interior and exterior temps and I'm not seeing any other obvious issues.

I would like to try and re-flash the software for my IHKA -- how do I go about doing that?

[Arith2]

No compressor running, it should be around 80 psi. If you can verify the compressor isn't coming on then you have a leak. If it is running, your buttons work and you have a leak. It could be a blend door problem but it's the least likely and will most likely show a code for implausible signal. I think you should measure both sides with a guage. I'm not saying it isn't the module but eliminate everything else first.

[erickhoyos]

Did you check the belt lol. Mine was old and cracked and it shredded itself one day and didn’t have AC for the longest time

[Fffrank]

No compressor running, it should be around 80 psi. If you can verify the compressor isn't coming on then you have a leak. If it is running, your buttons work and you have a leak. It could be a blend door problem but it's the least likely and will most likely show a code for implausible signal. I think you should measure both sides with a guage. I'm not saying it isn't the module but eliminate everything else first.

How would the low and high side have different pressures without the compressor running???

I put my gauges on it and I get 55psi with the car off and 55psi with the car on (high side and low side are both equalized.) The belt is fine but the compressor never kicks on.

[TexaZ3]

Bad AC switch?

[Arith2]

How would the low and high side have different pressures without the compressor running???

I put my gauges on it and I get 55psi with the car off and 55psi with the car on (high side and low side are both equalized.) The belt is fine but the compressor never kicks on.

You wouldn't.
55psi is low though it should still turn on. If your guage says 55psi and INPA says 33psi then there's something off there.

[Mr.wReckless]

Did you check the belt lol. Mine was old and cracked and it shredded itself one day and didn’t have AC for the longest time

Could it also be the compressor clutch not engaging properly? I can hear mine click and the revs change a bit when the clutch dis/-engages.

Regards

[Fffrank]

I bought a can of r134a to recharge it today and sure enough.
... Right on the can was a little guide of what your pressures should be. 50psi on both sides indicates that your compressor isn't running.

https://www.buyautoparts.com/blog/what-are-my-ac-pressure-readings-telling-me-about-my-ac-system/

So..... I'm back to square one. Why isn't my compressor running? If the clutch wasn't engaging I believe I would still see the snowflake come on the ihka display.

[Fffrank]

Spent some more time investigating today. Unplugged the compressor and put 12v to it..... Clutch engaged and it fired right up. Pressures looked good (but did see some dye on the back of the compressor.) Not a good sign that it's both leaking and that a previous owner added dye to the system.

When I plugged the compressor back in the IHKA started working correctly and it's blowing cold. It's not warm here at the moment so unknown whether it will continue to work..... But for now it's both a puzzle and an issue that has resolved itself (albeit maybe only temporarily?)

[eebamak20]

Look for it at www.buyautoparts.com