Please help, when I turn on the ac on my 98 E300turbodieasel I get heat(very hot) from left side and center vents and cold ac from the right vents.

The left has always been hotter than the right even when the heat only is on but I could live with that. The AC however is too hot even though the other side is cool. It does this almost all the time.
Is there some sensor that I should be looking at?

Appreciate some clues, thatnks.
Acerejo

http://www.continentalimports.com/ser_ic40142.html

You will find the secrets to testing all of the functions of the system as well as scanning for fault codes if you read this article and follow its procedures. Good luck!

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Almost always low on refrigerant! That is the most common cause.

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Thanks M. B. Doc,
If it is low on freon why is it nice and cold on the right side?

During the heat season the left side is always hotter than the right, could there be something wrong with the inside temp sensor?

Thanks again,
Acerejo

The expansion valve "sprays" the R134a into the passenger's side of the evaporator first!

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Thanks M B doc, this makes sense because it's been harder to keep up cooling on hot days in the last couple of years. I'll recharge it tonight and keep you posted.

Appreciate it

Acerejo

Thanks M. B. Doc, you were right about the low refrigerant being the cause for hot left and cold right.

I decide to recharge even though the gage showed sufficient charge (blue area), now both sides cool very nicely. I guess the gage that comes with the interdynamics charge kit is not that acurate. After adding a can I get the same gage reading but cooling is back.

I do have a set of manifold gages but I don't know what the values should be so I didn't even hook them up.

I still have the check engine and check engine electronics light on, a friend of mine scanned it and it came up with 180 code fuel cooler. He reset it but it came back a short time later.
I am not sure how accurate his scanner is but I don't think the car has a fuel cooler.
The car is running fine otherwise, I'll probably have to get the codes scanned by repair facility to pinpoint it.

Acerejo

P0 180 means that the FUEL temp sensor (front of injection pump) 000-078-44-49 & o-ring isn't functioning properly. OF course the wiring connector at that plug could cause that problem!

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M.B. Doc.
Thanks again, ironically the light didn't come on this afternoon, its slightly cooler out than the last couple of days, maybe that's why.

I will check the connector on the sensor though for loose connection and or sensor.

I appreciate your help again.

Acerejo

The correct fix for this car would be to replace the reciever/dryer and the hose running from it to the expansion valve. This is a very common problem. That I have fixed. The temp fix is to ad more freon and over charge the system which is dangerous. The problem will be back again. Usually on a hot day when you need the A/C the most. fix it right the first time! Good luck
Tech1

Yes, tech1 the drier/hose WAS a problem on 1996-97 cars but this is a 1998 E300DT and that has never been a problem on that year!

TO see if the drier is the problem simply feel the temp of high side, if hose or drier is cool enough to touch then it can restric refrigerant & act like expansion valve!

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Heat blows out of left side when AC should be on. OK, I have recently fixed a problem that appears to quite common from what I have read in posts on this message board, but not too many threads seem to have a full and complete diagnosis detailed, though I must say there were definitely some very helpful posts that lead me to the final fix. To make a long story short, I had a problem with both my evaporator temperature sensor as well as with my duo valve. The actual main problem was the duo valve (it was sticking). I have read many threads that said a common problem of heat blowing out the drivers side while AC should be on might be attributed to the freon charge being low, but I did not find any valid proof of that. In any case, here is how to diagnose and then fix what is wrong.

1) First thing in the morning preferably with the car sitting in the garage turn the key to the on position without starting it.
2) With your climate control on press and hold the “rest” button until the display changes (the left number should come up as “1”, the right number will be value for inside cabin temperature
3) Press the left “auto” button to toggle up through values and the right “auto” button to toggle back down the following are the values that are important to you and first thing in the morning they should all be within a degree or two. If not, then you have a bad sensor – (I had to replace my evaporator sensor which is under the dash in the duct toward the center on the driver’s side. Buy a new one and then you will know what to look for under there.)
1) Cabin Temperature
2) Outside Temperature
3) Left Heater Core Temperature
4) Right Heater Core Temperature
5) Evaporator Temperature
4) Once the car is all warmed up and you experience the problem where you are blowing heat out on one side (or possibly even both) while calling for AC, go to the above mentioned diagnostic display while the car is running and look at the heater core temperatures. When running full AC they should be somewhere in the 60’s or even lower. If you are having a heat on one side issue, you should see this right away by noticing a big difference between value 3 and value 4. The hot side might be up between 150 and 200.
5) With the AC still adjusted to “low”, open the hood and tap the duo valve with something metallic and see if that “Stuck high heater core temperature” drops. If it does, your duo valve is still trying to do what it is supposed to and is just sticking. If not, You may need to simply replace your duo valve and or test it electrically which is a whole other story (there are other threads in here that can help the ultimate do it yourselfer rewire one of these, but I think it is way too much work unless your are a skilled electrical circuits guy.)
6) If tapping your duo valve gets your AC blowing, let the engine completely cool, remove the three torx head bolts (remove the entire duo valve if you really want to do it right though it’s a bit of a pain to get off) and carefully slide it up. Pay close attention to the small parts that com e out and be careful not to drop any. Also be very careful not to crack or break the rubber gasket below the unit or you will have to replace it somehow and I am not sure how easy it is to get that gasket. I reused mine, so hopefully you can also reuse yours.
7) Once apart, you will notice the cone shaped pieces, this is what is sticking even though it does not look like there are any rough spots anywhere (at least mine did not). I cleaned these very carefully with a dremel tool wire brush attachment. Clean off any debris anywhere and be very careful not to damage the seats that these cones fit into.
8) Reassemble the duo valve warm the car up fully and be sure there are no leaks around the valve – That’s it – stick duo valve.
I cleaned mine about six weeks ago and the climate control has been working flawlessly after struggling for about a year or more. When I found through the diagnostics that it was definitely the duo valve, I was going to change it out, but found that it was over $200, so that is when I decided to take mine apart. Only took me about an hour to do the entire job – well worth the try.