[Nando_e90]

My ac is not reaching the temp that it should, and after following the diagnosis steps suggested in other threads by George, Mainbearing and other well valued members of this forum, I am certainly sure the issue is whether the expansion valve or the evaporator.

I have read that accessing the evaporator is a PITA, but haven’t found enough info related to the expansion valve. So if it is the case that can be replaced without removing the dash, I’d be willing to do it since it is not an expensive part.

Have any of you done it before?

[ZGator]

you can reach the evap expansion valve from inside the engine bay- it's bolted on the firewall - not too bad a job at all - must evacuate the system first, before taking it part, best to get a shop with a/c equip. to do that along with the vac, test, and refill.

that was my problem - I had high pressure but no cooling - guess they were a common failure point. Did mine several years ago and A/C still works great after the change. No nightmare dash dismantle evap replacement required - the VAC test would tell you if the valve fixed it vs evap.

[gbalthrop]

Originally Posted by Nando_e90

... haven’t found enough info related to the expansion valve. So if it is the case that can be replaced without removing the dash, I’d be willing to do it since it is not an expensive part.
Have any of you done it before?

I have NOT replaced my Expansion Valve, but it is on the engine side of firewall, and you just remove Microfilter Housings (upper & Lower) to access the Valve and High Side Fitting. Of course evacuation and recharge are required after. Make SURE not to leave open to atmosphere for 24 hours or more, or you will have to replace Desiccant. Make sure you have ALL necessary replacement O-rings/ Seals.

See three ISTA ScreenPrints, attached to NEXT Post, for Procedure. Please let us know how it goes, as there are others with similar issues. You might also indicate any test pressures & Evap Temps you encountered attempting to Diagnose issue.
Thanks,
George

[gbalthrop]

2006 330i Expansion Valve R&R Procedure per ISTA, 3 ScreenPrints, as described in prior post.
George

[Nando_e90]

Thanks to ZGator for the info and sharing the experience, and to George for sharing the procedure.

You might also indicate any test pressures & Evap Temps you encountered attempting to Diagnose issue.

Here are the values I found attempting to diagnose the issue. I followed the diagnosis steps using INPA suggested to AValidUsername in this thread: https://www.e90post.com/forums/showthread.php?t=1927665

(pdf attached with INPA screenshots)

Eninge off

• Outside temp: 35 C (95 F)
• Inside temp: 36 C (97 F) [measured separately]
• Evaporator temp: 39 C (102 F)
• Print Cooling Agent: 8.0bar (116psi)
• Right and Left mixed flaps: 0 (closed)

Engine running 2 minutes

• Outside temp: 35 C (95 F)
• Inside temp: 36 C (97 F) [measured separately]
• Evaporator temp: 17 C (63 F)
• Print Cooling Agent: 15 bar (217.5psi)
• Right and Left mixed flaps: 0 (closed)

Engine running 10 minutes

• Outside temp: 35 C (95 F)
• Inside temp: 32.4 C (90.3 F) [measured separately]
• Evaporator temp: 13 C (55 F)
• Print Cooling Agent: 15 bar (217.5psi)
• Right and Left mixed flaps: 0 (closed)

Key points here as I see it:

1) First of all, there are no leaks in the system. I’ve gotten it checked periodically and hasn’t been necessary to recharge refrigerant in the last 1.5 years. The last time was more than a year ago when I replaced the compressor pulley and needed to remove an A/C pipe to do the job, so I had to get a shop to evacuate the system first and then recharged again after pulley was replaced.
2) Second, the compressor is working well since the “Print Cooling Agent” measures 15 bars, which is appx. 220 psi, which also indicates the high side pressure is ok (if I’m correct). So compressor is not the issue.
3) Third, the right and left mixed air flaps remained closed during the whole process, hence no air is redirected through the heater core, so that part is also clear.

And here the problem:

4) Evaporator temp is above 10C (50 F) even after 20 mins with engine running, when it should be less than 10C (50 F), near 5C (41 F).
5) I also measured the temp of the air coming from the vents with a kitchen thermometer, and the air was flowing at 14C (57F), too high. Just for comparison purposes, I measured my office mini split A/C vent temp which was set up to 20C (68F), and the air was flowing at 4C (39F).

So at this point, as I understand, the reason of the air not flowing cold is either the Evaporator and/or the Expansion Valve.

And today I took the car to the air conditioning shop that I usually go to, and they measured the pressures with gauges. The high side was fine, appx. 220psi, but the low side was fluctuating, which could be a symptom of the Expansion Valve I was told, since it regulates it. Here is a video I took of the gauges connected to the low pressure side:

https://youtube.com/shorts/cmv8vTGtLrY?feature=share

So I will attempt to replace the Expansion Valve and will update later with the results.

[John 070]

Just going to chime in with some generalizations, not specific to the E9x.

Seems the ambient temp was 95F, and the evap was 55F. That's excellent bordering on too cold.

My car that feels "ice cold," I decided to measure it. It was 90F and relatively humid, and the vents were blowing 54F. So my belief that it was "ice cold" was subjective. My wife's SUV which I felt has bad AC that I just tried recharging, was about the same.

In a car, I hear the delta is between 30-37F drop.

That is not the case in a home, where it should be about 20-22F.

Your mini split blows out 39F? At what ambient temp? that doesn't sound right. 1, it's uncomfortable anywhere near the wall unit. 2, imagine the condensation.

Low refrigerant or low airflow also causes the evap to be too cold. That's how people can have a system freeze up in the dead of summer with ice going all the way out to the compressor on the low side line.

Just thinking about the refrigeration cycle, if your evap is a normal temp, 55F, when it's 95F outside, can it still be the TXV? I'm asking. My guess is no.

[Nando_e90]

Originally Posted by John 070

Just going to chime in with some generalizations, not specific to the E9x.

Seems the ambient temp was 95F, and the evap was 55F. That's excellent bordering on too cold.


Just thinking about the refrigeration cycle, if your evap is a normal temp, 55F, when it's 95F outside, can it still be the TXV? I'm asking. My guess is no.

I am starting from the fact (assumed) that the evaporator is not reaching the right temp. But if 55F is within the normal temp range for an evap, then I don't know what to think
But still, the A/C doesn't feel cold and when is hot outside it is not doing its work. Car feels hot even after 30 mins driving, which I don't think is normal.

[mainbearing]

The vent temp might be 55F on a 90F day, but I think the evaporator temperature should be in the range of about 2-5C (36-41F).

The high pressure of 217 psi looks fine. In the video looks like the low side is 45-50 psi while the rpm fluctuated. If so the high side should fluctuate too (I I noticed the high side gauge is not connected).

The low side should be around 30 psi to get the 2-5C evaporator temperature, and that is clearly not the case in the video.

I do not know if for some reason the expansion valve is not providing enough restriction or if there are problems with the volume of refrigerant not sufficient going past the expansion valve and into the evaporator.

If the expansion valve is not closing sufficiently, you should see a lot of condensation (sweating) on the larger low side pipe coming out of the expansion valve too.

And whether or not the expansion valve not closing is the result of debris in the system, including some that might block off parts of the evaporator, I do not know. The fact that you had to replace the compressor pulley meant the pulley's shear pins broke, indicating high friction within the compressor.

Originally Posted by Nando_e90

I am starting from the fact (assumed) that the evaporator is not reaching the right temp. But if 55F is within the normal temp range for an evap, then I don't know what to think
But still, the A/C doesn't feel cold and when is hot outside it is not doing its work. Car feels hot even after 30 mins driving, which I don't think is normal.

[Nando_e90]

Originally Posted by mainbearing

And whether or not the expansion valve not closing is the result of debris in the system, including some that might block off parts of the evaporator, I do not know. The fact that you had to replace the compressor pulley meant the pulley's shear pins broke, indicating high friction within the compressor.

I replaced the compressor pulley because the bearing messed up. In fact I replaced the bearing only. Here is a pic of how it was:

[IMG][/IMG]

Don't know if that also indicates what you say about debris in the system, and if it is the case that it is debris in the system, what would be the best way to proceed?

Thanks in advance!

[mainbearing]

The bearing might have failed from heat. I would think the shear pins or blocks would have failed, but guess not.

If the problem was really debris (we do not know for sure yet), could the small parallel flow channels in the evaporator have been blocked similarly to the expansion valve could not close? Therefore taking out a chunk of your cooling capacity?

An AC shop should be able to tell you more. AFAIK, you cannot flush a parallel flow condenser or evaporator.

https://www.brakeandfrontend.com/nev...a-c-condenser/

[dcarter94]

Nando, any updates on this? I have the same symptoms (proper ac charge, pressures look good, cooling fan running, INPA vent positions fine) but not enough cooling through vents.

[Nando_e90]

Originally Posted by dcarter94

Nando, any updates on this? I have the same symptoms (proper ac charge, pressures look good, cooling fan running, INPA vent positions fine) but not enough cooling through vents.

No!
I haven't been able to make any progress on that yet. Symptoms remain the same. I am planning to buy the expansión valve in the next order since I already have more than one issue to fix on the e90 so will try to do them all at once.

I'll update!

[dcarter94]

Sounds good! I’m thinking I might do the same with the expansion valve. Other than that I guess the only things left would be the condenser or evaporator (although I wouldn’t think the evaporator would be the problem).