AC blows warm air through one vent, even with new compressor

[herwawan]

They went with the Denso compressor - seems like that’s good, according to my research.

They replaced the dryer and it seems to have fixed it - they went on a 50 miles trip and measured 40F at the vents the whole time. They will take it on another test drive tomorrow before handing it over to me.

I don’t have the info about the o-rings but I would assume they took care of that while replacing the different elements? I’ll know tomorrow when looking at the job report and will let you guys know.

I’ve learn a bit thanks to that experience, thank you guys for sharing the knowledge!

You can also check the mixer valve, if it is stock in the position where it allows hot water to flow thru the blower box you all always hot air in the car. It happened to me and when i changed that the A/C was great again.

What’s the mixer valve exactly?

[duracellttu]

When you guys say ”drier” do you mean the evaporator (P/N 64-11-9-135-744)? Is that in the front of the car?

Which part is built into the housing under the dash that is a real pain to get to? I’m dreading that, should it need to be done.

[PetrolM3]

Which compressor did you go with? OE bmw or oem manufacturer?

Denso

[Pnick]

When you guys say ”drier” do you mean the evaporator (P/N 64-11-9-135-744)? Is that in the front of the car?

Which part is built into the housing under the dash that is a real pain to get to? I’m dreading that, should it need to be done.

A simple basic vehicle AC unit:

[Pnick]

They went with the Denso compressor - seems like that’s good, according to my research.

- they went on a 50 miles trip and measured 40F at the vents the whole time. They will take it on another test drive tomorrow before handing it over to me.

What’s the mixer valve exactly?

Wow...50-mile test drive and test it it again maybe for another 50-miles...You're pretty generous!

Mixer valves are the 2 solenoid valve looking thingy under the hood mounted on the driver's side frame below the brake booster. Those are what controls your heat.

[herwawan]

Wow...50-mile test drive and test it it again maybe for another 50-miles...You're pretty generous!

Mixer valves are the 2 solenoid valve looking thingy under the hood mounted on the driver's side frame below the brake booster. Those are what controls your heat.

Thanks for the schematic, really simple and helpful. And yes, I’m generous with the miles haha but they filed up the tank, they really are doing this right.

And now the great news! Problem fixed, AC is blowing cold and strong 💪

Replacing the receiver drier was the missing piece. I hope this can help others with the same issue!

[herwawan]

Update boys. After a week, again warm air... brought it back and here is the feedback so far:


« First thing we did was check for faults in the climate control unit and none were found. Hooked up gauges to your vehicle and the low and high side were higher than normal. Technician evacuated the AC system and found that the charge was over by 0.2lbs. We charged your AC system at spec on your last visit so we were shocked that we recovered a higher amount. We ended up recalibrating the AC machine twice. We then charged and evacuated your AC system twice to make sure the amount of freon was correct. AC is blowing cold. Technician is going to do another evacuation and recharge again just to make sure the amount of freon is correct again. Test drove the M3 for only 5-miles and AC is blowing cold. »

Does that ring a bell to anyone? I find it so odd. And I’m kind of at loss with this situation. I don’t think throwing parts at it will change anything so I’m glad they are investigating.

[Icecream]

Update boys. After a week, again warm air... brought it back and here is the feedback so far:


« First thing we did was check for faults in the climate control unit and none were found. Hooked up gauges to your vehicle and the low and high side were higher than normal. Technician evacuated the AC system and found that the charge was over by 0.2lbs. We charged your AC system at spec on your last visit so we were shocked that we recovered a higher amount. We ended up recalibrating the AC machine twice. We then charged and evacuated your AC system twice to make sure the amount of freon was correct. AC is blowing cold. Technician is going to do another evacuation and recharge again just to make sure the amount of freon is correct again. Test drove the M3 for only 5-miles and AC is blowing cold. »

Does that ring a bell to anyone? I find it so odd. And I’m kind of at loss with this situation. I don’t think throwing parts at it will change anything so I’m glad they are investigating.

Here is the thing, you said the passenger side was colder than the driver side. That is odd since it always fails the other way around. Did you ever check the mixer valve? Depending on which way the flow is and were the heater core is, that might explain the warm air on the driver side first.

[herwawan]

Here is the thing, you said the passenger side was colder than the driver side. That is odd since it always fails the other way around. Did you ever check the mixer valve? Depending on which way the flow is and were the heater core is, that might explain the warm air on the driver side first.

I asked - and they already checked it. The heater valve was not stuck open, not leaking, and was operating normally. They are not getting any heater valve faults in the climate control unit either... Replacing the unit as preventative maintenance would be quite expensive :/

[Icecream]

I asked - and they already checked it. The heater valve was not stuck open, not leaking, and was operating normally. They are not getting any heater valve faults in the climate control unit either... Replacing the unit as preventative maintenance would be quite expensive :/

well shoot.

[Flat-Six]

Glad you got it fixed, Going Forward....After you replace the Drier, make sure you pull a vacuum, then let the vacuum sit for a bit to verify no leaks. I just replaced my son's Compressor and Drier on his E46 328ci this weekend. Also make sure you weigh so you can track the amount of freon that goes in, along with watching the pressures. IIRC I think I put in 720g. On his, Low side was 40ish and High was 200 with 90 degrees outside. I pulled the vacuum for 20min and let it sit for another 30min to make sure I did not have any leaks before I charged it up. Blows Ice cold.

BTW, as expected, the Pass Vent blew warm as it was charging and was the last vent to go cold...

[herwawan]

So weird that my vent-symptom is inverted vs most haha

In the meantime, the shop worked on the car:

- They checked the charging pressures and they were a bit on the high side (245psi). Should be around 210-220psi.
- They got the freon at and it was overcharged by 0.2lbs
- They recalibrated their A/C machine and recharged the system with the correct amount.

Now it's blowing cold again for now. I'll drive it around this weekend (heatwave yay) and we'll see how it goes.

Crazy crazy this whole thing.