PJmak

I googled this and tried a few different procedures but nothing worked.

My problem is the following:

Car blows air but not cold, front radiator fans are constantly on from the moment I start the car until I shut it off. Also I just had my freon topped of yesterday and the guy did a vacuum test and he found no leaks.

He told me the AC compressor is not engaging and that the computer needs to be reset but he says he needs three hours to check everything and do that, and I don't really wanna pay him that much.

I heard the system can be diagnoses through the AC console in the car. Does anyone know the correct way to do this on 98 and up W202s?

503C43 ////AMG

BOOM!

PJmak

I tried those and half the numbers and values weren't showing for me on the screen but I figured out why once i discovered the problem.

One of the plugs in the back of the console was disconnected

Previous owner was replacing the stock radio with the OEM command and probably left it unplugged. This whole time I thought there was a leak or maybe my compressor went out.

My ac works perfect now

But thanks for your reply

JohnnyRock

Great fix! BTW, does anyone know what that damn, "EC" button does???

Super B

It turns off the AC compressor to save gas.

KJI3jflarryfe93

always block the EC button when doing off the record driving

seriously if you wanna save gas, turn on the ignition to 2nd position, press EC to block then start your car, compare with and without.
these c43's are heavy on gas at start up.
after 5 - 10 min of driving unblock the EC.

JohnnyRock

OK, now that I know what it does, how the hell do I turn it off or de-activate it? Or should it always be on?

vlad957

my Economy mode doesn't turn off either. And the ac doesn't blow as hard even if its on max. I checked the freon it was fine. Im not sure what it could be maybe the blower motor?


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nd4spd13

Er, press the button again? That's how it's supposed to work at least

I also don't think you need to do it with the engine off. Pretty sure the button just engages/disengages the A/C clutch at any time.

JohnnyRock

Hahaha...Yes, I tried that, at least while the car was running, doesn't seem to want to turn off? Maybe I need to try pressing the button with the key in the 'start' position before actually running the vehicle???

I'll report back.

RobertG

When the economy light is on , it means your compressor is not engaging.
it could be a sensor or wire problem .

nd4spd13

Interesting. Does the light turn off but the A/C just doesn't come back on? Or does nothing happen?
I'm pretty sure the manual said nothing about doing it before or after turning the car on/off. But let us know if it works!

nhmercracer

Do the climate controller test and record all the values. Post them here, along with your static refrigerant pressures. You need to know both high and low side pressures, so one of those "quick fill" R134 cans with the gauge will not do the trick.

I would have to search for the static (compressor off) refrigerant pressures, as I cannot remember them. However, one value you can start with is the evaporator temp. If it is too high, the compressor will not cycle. This is caused by the temperature sensor on the left side of the AC evaporator box failing. When it fails, the temperature is seen as too high. This shuts off the compressor to prevent internal damage. The controller believes there is no refrigerant.

The best way to check for this is to start the car, and open the hood. Have someone else turn on the AC, and set the coldest temp. The compressor should come on (the center will turn) for a short time. If the compressor then turns off, chances are this is your problem. This is all assuming you checked the static pressures, and they are acceptable

Good luck.

pedrobenz

I need help on this. My 99 C43's A/C sometimes would work and sometimes will not. I have taken the numbers this morning but could not figure out what these numbers mean. Can anyone please help. Here are the readings:
01 - 77F
02 - 65F
03 - 74F
05 - 123
06 - 194
07 - 00.4
08 - 69F
09 - 50F
10 - 495
20 - 0
24 - 14
40 - 03
41 - 03
42 - 02
43 - 6-C
50 - 73F
51 - LO
52 - 50F
54 - OFF

Can you please help me figure out these numbers and also please let me know what you think is wrong with my A/C given these numbers. Thanks I'm advance.

pedrobenz

Anyone?

Sulaco

07 is refrigerant pressure and it's reading 00.4. You either have a leak and thus low freon, or your system cannot detect pressure and thinks it is empty.

pedrobenz

Thanks sulaco. It is actually working intermittently. Yesterday, when it worked, the refrigerant pressure was 15.7. But this morning when it was 60F, the pressure says LO. Will the A/C work when it's cold outside? I am assuming yes. Yesterday the EC went on and I pulled the code and it says 241 and 24.1 which means refrigerant fill. Is it safe to assume that I need refrigerant?

Sulaco

I would not assume pressure is the problem, still. Sounds more like intermittent electronic fault (a sensor or the clutch). Have your pressure checked manually using gauges (most AC shops will do a quick "diagnose" for free, and can tell you what your pressure is).

And pressure won't make it work intermittently. Once your pressure drops below a certain point, it simply won't work at all until more is added in. Keep an eye on the 07 in the diagnostic settings. If you see that number varying wildly, you've got a sensor to track down, or your climate control unit is faulty. IIRC there's a pressure sensor that could likely just be failing. Have you tried pulling trouble codes? That would help, too.

pedrobenz

Thanks again. Yes, I tried pulling the codes and I only get 241 and 24.1. Where is the pressure switch located? Is that easy to pull and replace? It maybe the pressure switch too...

Sulaco

I don't know where it is, but your theory makes sense to me, too.

http://www.partsgeek.com/catalog/199...re_switch.html

Look at the picture of it and then inspect your system until you find it, is my best guess. It's probably near the firewall, near the compressor, or near the evaporator.

popey24

01 car cabin temperature
02 outside temperature
03/04 heater temp left/right (only one available in our car)
05 Evaporator temp
06 Engine water temp
07 condensing pressure
08 condensing temp

The others are without interest for climate control. Maybe 24 - Battery Voltage could be of interest.

pedrobenz

Thanks popey24. Do you know what the normal values for these numbers you gave? I just filled one can of refrigerant and the values seems ok. It goes up to 15.7. However when I drove back home, on the freeway, the condenser pressure keeps going down and it doesn't feel very cold. The temp outside is 72F. Also I noticed that when it gets cold, my number 2 reading is really high. Do you think it has to do with that? When it is working fine, the nbr 2 goes up to 135F. When it is not working, the value is similar to what I see in the dash. Any ideas?

popey24

I can tell you values in °C and bar only. You Need to convert.

01 car cabin temperature
Sensor lokated at the rof (inside the light board behind mirror, you can see some air Slots, there is also a fan inside).
In normal condition around 20°C, if car stands under the sun in summer, you can have 50°C and more, in Winter can be pretty cold in the morning

02 outside temperature
Outside temp is keasuren at the front bumper driver side

03/04 heater temp left/right (only one available in our car)
If the heating System is not running (mximum cooing) or the temp should be lose to the evap temp 05

05 Evaporator temp
Evap Temperatur in cooling mode is around 2°C. But the probe is measuring the air Close to the evap. It should be 7-12°C in cooling mode.
If cooling is off normaly the temp is around outside temp (the Evaporator is located bevore the heater). If you Switch on and Change to reading mode directly, you can wtch the temp going down to under 10°C within some minutes.
The probe is lokated in the Drivers feet area direction behind the radio. For Exchange I think you Need to remove or at least open the cover under the steering wheel. This sensor sometimes gets brken in fact of water and it will disturb your climate control. If damaged you will read totaly strange values (f.e. 65°C).

06 Engine water temp
should be the engine water temp you see in behind the steering wheel


07 condensing pressure
If cooling System is running, the pressure shoud be 12-20 bar (condenser fan Switch on/off depending on the pressure). I fan is damaged, the System will switch of by high pressure.

08 condensing temp
Condensing temp is depending on condensing pressure. There are diagrams available to calculate temp from press and vice versa (refrigerant is R134-A). In cooling mode should be 30-50°C.
If System is off temp should be Close to outside temperature and also pessure is depending on outside temp (should be something around 4-8 bar I think but I don't have a diagram just now).

pedrobenz

Thanks again popey24. It looks like my ambient temp sensor and my evap temp sensor are bad. My #02 reading goes really really high. It goes up to 135F when my dash reading says 70F only. I think they use the same sensor so it maybe a bad sensor.

My #05 reading (evap temp sensor) is never below 100F. It is always above 100F. I am guessing the evap temp sensor is bad too. Will it cause the compressor not to kick if the evap temp sensor is bad?

popey24

Ok I converted Celsius/Fahrenheit... 100F<>38C. Exchange the evap probe. The new Version should have better Isolation against water.
Concerning outside probe... did you read during driving or car was stopped?
Anyway the outside temp should not have influence on the climate control except it is pretty cold.