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

[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.

[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...

[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.

[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]

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]

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.

[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!

[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.

[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:

[PetrolM3]

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

Denso

[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.

[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?

[TropicalM3]

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.

[clawhamm3r]

Yeah, I should rephrase that I suppose. I don't think its common to replace the drier each and every time the system is opened. But moisture is introduced when the system is opened and if the drier is original to the car its probably a good idea to replace it.

It's one of those "supposed" to things. Can you reuse the copper crush washer on your oil drain bolt? Yes. Will it leak? Maybe. But if it does do you want to drain the system/oil to fix the problem? Probably not. Esp when it's $25 and like 10-15 minutes to swap I'd rather just do it. And like you said if it's old definitely do it. If you just replaced it and have to open the system back up to chase the problem further...start there with opening the system and tape it off lol.

OP mine has been leaking for years and when it gets low enough it blows warm on the passenger sides. I've read for years that the hissing behind the dash and the other symptoms was the orings on the expansion valve. I recharged it every 1.5-2 years as my fix lol. Finally decided to do it last month, replaced the valve because it was another $30 part while I was in there. Bought the ECS O-ring kit which was missing o-rings and some were wrong. I need to post an FYI on here about that.

Anyway, I replaced the valve, drier, and all orings in the system after having it discharged. Took it back to get it recharged and it's been colder than it's ever been...let's see how long it lasts.

[Rkymtnrider]

Just went through this same ordeal. A/C stopped blowing cold (starting with passenger vent then all). Had a noisy compressor and a leak on the condenser connection. Due to mileage and cost to refill, I decided to replace compressor, condenser (gets beat up by stones and can end up leaking) as well as the drier (needs to be replaced every time you open the system), expansion valve, schrader valves and all o-rings. The shop pressure tested the system with nitrogen (which also soaks up all the moisture) and only once they were sure there was no leak, they flushed it (I believe they call this 'vacuum flush') and then filled it to spec including the right amount and type of oil for the compressor. Working great since then. Got all my parts at FCP euro so I never have to pay for them again in case of issues in the future.

Sounds like you still have a leak and I’m surprised the shop didn’t pressure test the system before they determined it was your compressor and before they recharged it. If they missed a leak, they should at a minimum recharge it for free once the leak is fixed.

Good luck!

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