I have a 84 euro 240d which I acquired two years ago. The car came with an aftermarket ac setup. This past summer I overhauled it with a new sanden 508 compressor, expansion valve, reciever drier and a large parallel flow condenser and charged the system with r12. This combination has worked very well for me. I live in Phoenix. In the mornings ambient temps are in the low 90's, but I can get 40 degree air out the center vents on high fan speed and even in the mid thirties on medium speed. Coming home today the ambient temp was 112 degrees. Despite this I still got 50 degrees out the center vents on high fan speed and right at 40 degrees on medium fan speed. The one problem I have is that the ac system seems to work better at low driving speeds(20to40mph) as opposed to lets say 70mph where the air simply isn't as cold, not to mention the fact that if I drive at 70 for an extended period of time the blower speed slows down on its own an starts putting out warm air. If I return to slower driving , blower speed starts to pick back up and air starts to get colder again. Any Ideas as to what is going on here?

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Bob Jenkins

BUMP for a good question. I am considering trying to throw a PF condenser in my car and if this is common, then I don't think I want one!

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1985 MB 300D/T

Fell off the WVO bandwagon when people started trying to charge $2.50 a gallon for dirty vegetable oil.

when you are going 70, can you feel the compressor clutch engage and disengage?

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Cheers,
Robert

I believe the compressor is staying on all the time as I don't feel it turn on or off.

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Bob Jenkins

It is possible for the system to freeze up the evaporator if the compressor does not cycle properly. When it freezes up you get reduced air flow through the evaporator and the cooling effect actually decreases, even though the evaporator is a block of ice. Turning off the A/C when this happens often results in fog coming out the vents as you go along.

The other thing that can happen, and I believe could be your problem, is excessive outside air coming into the system. You may want to manually force the recirculator door to cause only recirculation of inside air during the hottest months. That's what I need to do on my 300SD, but have not determined how to do that yet.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

mono valve could be letting some coolant through when engine is running constant rpm's at highway speed

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85 300d in progress

I also have an 84 euro 240D with aftermarket air. There IS no monovalve. I also believe that the problem is outside air. with 40 degree vent temps, I don't think that there is an evaporator freeze going on.

I personally would not go to a different compressor. The Sanden is REALLY tough to beat. One of the advantages to your car is the simplicity and effectiveness of this a/c.

What are your pressures, and your vent temps at particular outside temps?

I don't recall the pressures when I charged the system back in may, the vent temps get to around 40 degrees on high fan speed and in the mid to upper thirties at a lower fan speed when ambient temps are in the 90s or below. In lets say 110 degree weather, vent temps are around 50 degrees high fan speed and lower 40s at a slower speed. I agree with you larry about the sanden compressor. I have been very pleased with it. Another thing I noticed is that vent temps at the outer two vents are not as cold as the center vents. Do you think this to is caused by outside air geting into the system?

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Bob Jenkins

50F air vent with 115F outside. Darn!!! i get 50F with 95F outside.

We need pix of the Sanden Compressor!!!!!!

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Aquilae non capunt muscas! (Eagles don't hunt flies!)


1979 300SD Black/Black MBtex239000mi
1983 300TD euro-NA. White/Olive Cloth-MBtex 201000mi. Fleet car of the USA embassy in Morocco
1983 240D Labrador Blue/Blue MBtex 161000mi

I don't think that the difference in vent temps on the outside vents is an indication of outside air, but you need to try to determine if this is the problem. My euro aftermarket air, which I fully expect is just like yours, has a screwy setup of the control levers. Experiment with them to see if there is any position that will give you different vent temps.

The Sanden compressor mount is quite simple. It is a mount that bolts to the lower left of the block, mounting the compressor with four bolts to the mount with two in the back and two in the front. It mounts the compressor in a solid position and uses and idler for belt adjustment.

I don't have a digital camera from which I can download to the computer, or I would take a picture of one of them. If both compressors weren't in place on these cars, I would bring one of them with it's mount to the tech session to show you, but I don't want to blow the charge on either car.

Here are some pics of my sanden 508 compressor. They are not the greatest, buy you can get an idea.

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Bob Jenkins