dllhg

I know our ACs stink and stink even more with Killer Chiller installed. Have had car for over 2 years with kit on it. Started getting warmer at lights especially. Before I would have to turn fan down on freeway on a hot day now I keep it full blast and barely stay cool enough. Stop light it barely works and I get nice and hot unless I rev it past 2K.

About 3 months ago it totally stopped blowing hot air. Replaced the compressor after local indy trouble shot it. Now it works like it did right before it went out completely. Very poorly. He weighed out the freon. Then added something like 6 Oz for the killer chiller. Went back a few weeks ago and he added a few more OZ and it did nothing. Killer Chiller water is also about 10 degrees warmer than normal. Will go down to 50-52, normally it is 39-42.

Any ideas what else it could be ?

BC928

Did he evacuate and test vacuum? Why is he adding mass? More freon does not make it cooler. Is it leaking? What are the high and low pressures?

Hulk

^^^^^ this. More is not always better with our ac system. Only put as much as recommended even with the KC. Also when changing the compressor they also recommend that you change the dryer.

Denroll

Have you looked into changing that hose on the low pressure side? There's a TSB out about the inside layer of the hose collapsing and causing weak a/c. I changed mine out as well as the desiccant canister and it made about a 16 degree difference with the temp set to maximum low.

nanayaw6

Unlike most here, my car's AC has been great the whole time I've owned it. The only time I had issues with it not cooling properly, it turned out to be a failing interior temperature sensor (the one housed in the front dome light/OCP). Replaced the thermistor in there and the AC was back to perfect. I live in hotlanta FWIW.

Denroll

^Was that an easy thing to swap out or is it completely ridiculous as in "remove dash, remove engine, take wheels off, reach up through exhaust on both sides simultaneously, loosen odd-sized Torx bolt that requires a special order, remove and replace sensor"?

nanayaw6

Its not so much hard as it is annoying. You have to pull the dome light out. There are some videos for that on youtube. When you open the dome light assembly, you will see the little fan that sucks in cabin air and blows it over the sensor.
In my case, the solder holding the sensor on had broken free leading to intermittent readings for ~140F to ~39F IIRC. You can see the value with Star.

Denroll

Cool. How much was the part?

nanayaw6

Old resistor legs broken off during removal.





New resistor soldered in.

Hulk

1408300008

nanayaw6

Resistors were dirt cheap for a bag of them.
Here's a link to the one I used:


I should still have them laying around somewhere in the garage. If anyone needs some, I'm happy to mail them a few.

My AC would go from barely cooling to not cooling at all in the summer. In the winter, it was doing a sloppy job at heating as well. Hooked up star and noticed the fluctuation with the interior temp sensor and of course no error codes were triggered. Cleaned around the sensor and it was good for a short while then failed. Opened the dome light and found one of the legs of the OEM sensor broken.

If you decide to just clean the dust by blowing compressed air through the fan intake in the dome light (passenger side), be very gentle so as not to damage the sensor with the stream of air.

DVC

Thank you Nanayaw6!

STAR is telling me to R&R this part.

nanayaw6

Hit me up if you need some of those resistors or tips on the repair.

SPatykAMG

Did the shop not recommended replacing the dryer at least. This should be standard being the car is at least 9 years old.

DVC

Thanks brother, you're the man

dllhg

Yes he did. Adding more Freon because of added lines for Killer Chiller. No leaks. I dont remember the high and Low but he said they were good and we confirmed this with Joe Kincaid.

The biggest thing that stands out to me is that it barely works at all when idling at stops or when I let off the gas but it works decently when 2K + RPM. I was told that indicate low head pressure. Usually that is caused from low freon but I cant see how I would still be low. I believe he initially put in 2.5 lbs. We then added -23 OZ then again another 2-3 OZ with no improvement. MY fans also suck. The fan force is about half of what every other car I have owned. You have to very carefully aim them to feel the air hitting your face. Still an issue with not being cold too though.

Denroll

Check out some of the parts on this page:

http://www.ecstuning.com/Mercedes_Be..._Conditioning/

I replaced that desiccant element. I didn't pay 3x the price for the OEM one, either.

dllhg

Thanks

I did replace the dryer when we did new compressor.

Denroll

The hose might be the culprit, then. Here's the part:

http://www.ecstuning.com/Search/Site...815/ES1768033/

Shifter

This should not be a hard problem to diag for a competent tech. To rule out KC, simply loop it back to stock. As the #2 post says what are the high and low pressures at idle?

dllhg

Any way to tell if its the hose first ? I know its only $120 but you add evac refill and hose install and I will be at least $500 into it.

As for high and low pressures I just remember we told Joe Kincaid what they were after filling and he said they were good.

Hulk

I like joe but with Benz it's diff Than ford.I had to Play with the freon levels until it was perfect, on my buddies other car it needed less and on another sl55 it needed exactly mb spec. Start off with a little less than what the spec says on your hood and then wait, drive around and see, then add more if needed. The fan strength has nothing to do with the compressor, if you think you might need a new fan it's easy to change, it's under the glove box took me about 45 min from start to finish?

Also check the expansion valve to the KC they have tendency to fail

dllhg

Well we have it over spec for sure. Probably by a good 4-6 OZ. Seems it would need more with the added lines and expansion valve etc. Joe thought it would need atleast 4 more OZ over stock... I did replace the expansion valve with a new one when I did the compressor.

Can I remove an exact amount ? Say remove 2 OZ at a time or something ?

My fan is terrible. Never had a car with such a weak fan. I just thought thats how there were on our cars. Maybe a new fan is in order then. Do you guys feel lots of air hitting your face ? I shut the rear vents and the passenger one just to feel decent air on me and even then its like 50% of my other cars.

Hulk

No you can't take out just a little, do a total evac and vacuum. Then start at 1.9 (iirc stock is 2.0-2.4) on the freon then work yourself up from there, you don't need more because of the KC, I'm at exactly spec and I'm fine and if more was needed 4oz is a lot.

On the fan since I put in the new fan yes it's stronger than before.
If you can find a fan for cheap used try that first

Rocman8

this hose failure is quite common and has stumped people over and over. you NEED to check this before anything else. with the ac running at max cold use an infrared temp gun and read the temp right where it almost attaches to the compressor then check the temp at the other end of the line right about where it attaches to the other line. there should not be much temp difference from one end of the line to the other. for instance if the line at compressor is 80 degrees and at the upper separation point its 35 then the line is restricted.
or evacuate the freon and pop the line off from the compressor and look inside of it for separation. the drier is recommended to be replaced anytime the system is opened.
did they add oil when the replaced the compressor?