[Nando_e90]

I'm here to share my experience on how I fixed my 330i air conditioning system. Over the years, I’ve read a lot about poor A/C performance while trying to find a solution, so I hope this might be helpful to some members.

My A/C wasn't effective when the outside temperature was high. At noon, it was especially uncomfortable, particularly if the car had been sitting under direct sunlight for hours. At night, it was fine, especially if it was raining. I lived with this issue for years. I read many threads, but they were all inconclusive. Some people claim that German A/C systems, in general, are less efficient than those of other brands, so it’s "normal." In fact, many E90 owners report having A/C that’s cool but not cold enough. On the other hand, I’ve also read about E90 owners in hot places like Florida, Texas or Europe who are happy with their "ice cold" A/C system.

I took the car to several A/C shops, but no one could offer a solution. They didn’t even recognize the problem. I had multiple evacuations, vacuuming, and recharges of the system. I also had the condenser cleaned using high-pressure water sprayed through the kidney grilles.

So, I started to learn how automotive A/C systems work. With the help of some members on other threads in this forum, I ran some diagnostics using INPA. I found a direct relationship between the outside temperature and the evaporator temperature. When the outside temperature was high (>86°F) and the car had been sitting under the sun, the evaporator temperature reached only 11-13°C (51-55°F), and the air coming out of the vents was only one or two degrees warmer. If the outside temperature was high, but the car was in a garage, the evaporator temperature was a little better—maybe in the 7-10°C range—but still inefficient. At night, there wasn’t a problem, and the evaporator temperature reached 2-4°C almost all the time, as it should. This was helpful because it allowed me to rule out other possible causes, like a malfunctioning blend door or even a dirty evaporator. The issue was that the refrigerant temperature the evaporator was receiving wasn’t low enough.

At first, I thought the expansion valve might be the cause. According to AI, “The expansion valve regulates the amount of refrigerant that enters the evaporator based on the cooling demand, or the amount of heat that needs to be removed from the air inside the cabin. This ensures the air conditioning system operates efficiently and maintains the desired temperature inside the vehicle.” So, a defective valve could lead to an inefficient evaporator temperature. I replaced the valve, but nothing changed.

After doing more research, I found that the refrigerant might not be cold enough when it reaches the evaporator because the condenser wasn't removing all the heat. As AI states, “The condenser essentially prepares the refrigerant for the next phase (expansion and cooling in the evaporator) by removing the heat it has absorbed from the cabin.” This is why, on rainy nights, the evaporator temperature reached the 2-4°C range, as there wasn’t much heat to remove, and the condenser could do its job properly.

So, I decided to replace the condenser and ordered a new Nissens condenser with a desiccant/dryer included from RockAuto. I installed it myself last week, and after that, I had an A/C specialist perform a proper vacuum and refrigerant charge. And guess what? Problem solved.

Not sure exactly if it was the condenser itself, the dessicant or the vacumm/charge but now, even at noon, with hot temperatures outside, the air coming out of the vents reaches 2°C after a couple of minutes of operation. I haven’t checked the evaporator temp with INPA, but I don’t need to—it’s working great.




So, if you’ve been dealing with a similar issue, take the time to understand how the system works (if you don’t already) and run proper diagnostics, especially checking the evaporator temperature.

[Fredo]

Great info here. Thank you for sharing with us.

[lowrydr310]

Did the condenser look OK visually? Any bent fins?

Do you have to add any oil when replacing the condenser?

I have been suffering from poor AC on my 335 and learned a lot recently. I thought it may have been the expansion valve but when I don't have cold air I'm not seeing the high side pressure increase when the compressor is engaged. I can hear the compressor running but the pressure doesn't rise, and then seemingly at random it'll start to increase and cool (but not cold) air blows out.

I thought maybe my condenser is bad, lots of bent fins and poor airflow:


However the high pressure not rising makes me think it's a compressor issue either faulty connection from the signal wire or just a mechanical fault.

Glad you got yours resolved! I have a few months before I have to worry about cool air inside the car, but I do need the drying capabilities for the defroster.

[Nando_e90]

Originally Posted by lowrydr310

Did the condenser look OK visually?
Any bent fins?defroster.

Yes, it looked ok even for a 19 year old one. No significant bent fins.

Originally Posted by lowrydr310

Do you have to add any oil when replacing the condenser?

Yes. The a/c specialist who did the vacuum and charge job, he said oil had to be added.

Originally Posted by lowrydr310

I have been suffering from poor AC on my 335 and learned a lot recently. I thought it may have been the expansion valve but when I don't have cold air I'm not seeing the high side pressure increase when the compressor is engaged. I can hear the compressor running but the pressure doesn't rise, and then seemingly at random it'll start to increase and cool (but not cold) air blows out.

I thought maybe my condenser is bad, lots of bent fins and poor airflow:


However the high pressure not rising makes me think it's a compressor issue either faulty connection from the signal wire or just a mechanical fault.

Glad you got yours resolved! I have a few months before I have to worry about cool air inside the car, but I do need the drying capabilities for the

According to the AI, expansion valve can cause those symptoms as well:

”What happens when the expansion valve malfunctions?

If the expansion valve becomes clogged or doesn’t work properly, the refrigerant flow is disrupted, causing fluctuations in both high and low pressure. This leads to the following issues:

1. Insufficient refrigerant in the evaporator: If the valve remains partially closed or is clogged, it won’t allow enough refrigerant to pass into the evaporator. This results in low high-side pressure since the compressor isn’t receiving the necessary refrigerant flow to maintain proper pressure.
2. Pressure fluctuations: When the valve temporarily opens or the blockage clears momentarily, refrigerant flows suddenly into the evaporator, causing high pressure to increase. At that moment, the system starts cooling effectively, but the problem may recur if the valve continues to operate intermittently.
3. Intermittent cooling: Due to these fluctuations in flow, the air conditioning only produces cold air when the valve allows an adequate flow of refrigerant into the evaporator. This explains why, in your case, the high pressure sometimes rises and the system begins cooling, but then it drops, and cooling stops”