06 CDI AC troubles solved.
07-30-2015, 09:02 AM
#1
Junior Member
Thread Starter
06 CDI AC troubles solved.
I am posting this in hopes of helping folks with the type of AC problems I was having. First, the AC in my car never has worked great since I owned it. I have 2 e320's an 03 and an 06. The 03 is my wife's car and you can hang meat inside her car, mine not so much. Hers has tinted windows and I attributed the difference to that but over time the performance of mine deteriorated to the point that my car was closer to a sauna than an air conditioned car.
My car did the AC not working unless you turned the system off and on a few times, sometimes stopping the car and turning the car off and on again would get it going. Once it was running it would cool the car on the highway only. It had to be moving. After about 5 miles the car would cool down. Not good in town. It always worked acceptably below 90 or so. I thought the heater valve was bad but after reading up on that I decided it wasn't. The other thing I noticed is that my wife's car at idle would sound as if there was a turbine engine starting as the radiator fan spooled up to provide airflow to the condenser because the car was sitting still. Mine never did. In my mind I thought that MB hand complaints about the noise and fixed it on the 06. My car got to the point of no cooling at idle. You might as well have opened the windows because it was going to be cooler and on the days with heat indexes of 100 plus degrees the car was just horrible to drive. Well, the first thing was that there were not any AC codes. What were the pressures in the system? Hard to tell because this car uses a variable displacement compressor, but I will say they looked good, to a little low on the high side, but generally they were Ok. So, I was pretty confused. First I replaced the expansion valve and dryer. Recharged the system and the pressures were about the same as before but the AC worked better, but still not where it should have been. So after thinking about what to do I decided to replace the AC compressor control valve and recharge the system. I replaced the valve, it is not terribly hard to do, but it is easier if you do it from under the car. Anyway I replaced the valve with the ignition off. Once I replaced the valve and tried to charge the system I could not get the AC compressor to come on. The AC button flashed red. So, I had to go to a garage and have the AC pressure switch and temp switch code cleared. After the code was cleared the compressor came on and the car started to cool It was about 95 as I was charging the system and as I go the closer to the amount of freon needed my (car idling) the turbine engine sound started as the fan speed increased rapidly. I had never heard that from my car before, but had a feeling that meant more heat was coming out of the system and the car would cool better. Once it was properly serviced I noticed I had cooling at idle, and was getting about 40 degree duct temps, once I was going down the highway I get around 36 degree temps! I can now hang meat in my car!
I don't know how many other types of compressors that MB uses on the W211 but mine was a Denso 7SEU17C and the I purchased the valve at www.polarbearinc.com The guy there is really nice and spent some time talking with me about the problem. The valve I purchased was the EX 004D from his site. 77.84 shipped.
On more thing, if you don't have a tool that will scan body module codes you might able to disconnect your battery before you change the control valve and that might stop the code from showing up. Hopefully this will help some of you if they symptoms sound the same.
Also, be aware that the control valve is in the pressurized part of the compressor, so the system needs to be evacuated before you pull it out, or it will FLY out when get the snap ring out! I posted a picture of the thermometer in my car, 97 degrees, 60 percent humidity and I'm loving it!
My car did the AC not working unless you turned the system off and on a few times, sometimes stopping the car and turning the car off and on again would get it going. Once it was running it would cool the car on the highway only. It had to be moving. After about 5 miles the car would cool down. Not good in town. It always worked acceptably below 90 or so. I thought the heater valve was bad but after reading up on that I decided it wasn't. The other thing I noticed is that my wife's car at idle would sound as if there was a turbine engine starting as the radiator fan spooled up to provide airflow to the condenser because the car was sitting still. Mine never did. In my mind I thought that MB hand complaints about the noise and fixed it on the 06. My car got to the point of no cooling at idle. You might as well have opened the windows because it was going to be cooler and on the days with heat indexes of 100 plus degrees the car was just horrible to drive. Well, the first thing was that there were not any AC codes. What were the pressures in the system? Hard to tell because this car uses a variable displacement compressor, but I will say they looked good, to a little low on the high side, but generally they were Ok. So, I was pretty confused. First I replaced the expansion valve and dryer. Recharged the system and the pressures were about the same as before but the AC worked better, but still not where it should have been. So after thinking about what to do I decided to replace the AC compressor control valve and recharge the system. I replaced the valve, it is not terribly hard to do, but it is easier if you do it from under the car. Anyway I replaced the valve with the ignition off. Once I replaced the valve and tried to charge the system I could not get the AC compressor to come on. The AC button flashed red. So, I had to go to a garage and have the AC pressure switch and temp switch code cleared. After the code was cleared the compressor came on and the car started to cool It was about 95 as I was charging the system and as I go the closer to the amount of freon needed my (car idling) the turbine engine sound started as the fan speed increased rapidly. I had never heard that from my car before, but had a feeling that meant more heat was coming out of the system and the car would cool better. Once it was properly serviced I noticed I had cooling at idle, and was getting about 40 degree duct temps, once I was going down the highway I get around 36 degree temps! I can now hang meat in my car!
I don't know how many other types of compressors that MB uses on the W211 but mine was a Denso 7SEU17C and the I purchased the valve at www.polarbearinc.com The guy there is really nice and spent some time talking with me about the problem. The valve I purchased was the EX 004D from his site. 77.84 shipped.
On more thing, if you don't have a tool that will scan body module codes you might able to disconnect your battery before you change the control valve and that might stop the code from showing up. Hopefully this will help some of you if they symptoms sound the same.
Also, be aware that the control valve is in the pressurized part of the compressor, so the system needs to be evacuated before you pull it out, or it will FLY out when get the snap ring out! I posted a picture of the thermometer in my car, 97 degrees, 60 percent humidity and I'm loving it!
Last edited by Ray_G; 07-30-2015 at 09:06 AM.
07-30-2015, 03:48 PM
#2
Super Member
Thanks for the information. When I first start my cdi, the fan sounds like a turbine, but slows down after a couple of minutes.
Mike T.
Mike T.
07-30-2015, 07:44 PM
#3
thank you for this write up, the ac in my 06CDI seems ok but not near as cold as my 08ML
have been wondering about a possible weak compressor etc so this is good info to have and look into
have been wondering about a possible weak compressor etc so this is good info to have and look into
07-31-2015, 08:15 AM
#4
Junior Member
Thread Starter
clvincent, if the control valve goes bad that is exactly what it is, a weak compressor. The problem is that you have to decide if the compressor itself is weak or the valve causing poor performance. My compressor was quiet and seemed to put out decent pressure, just no volume. So I took a chance and it worked. I guess this is one of those things you never know about until you try it.
