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My AC pump was stuck so I replaced the condensor, filter/dryer, expansion valve and the compressor. I also flushed the hoses and the evaporator. After filling and resetting the ''low refrigerant pressure'' error, the AC still doesn't work. I've checked the sensor readings with my iCarsoft i980, and everything seems to be okay, exept the refrigerant temperature sensor, this says that the temperature sensor reads a value of -99 degrees Celcius. The part number for this sensor is A0045429018. On ilcats.ru, where I can see all the part numbers for my VIN number it says that this is a pressure ánd temperature sensor. I thought this was strange so I replaced that sensor too, however the new one also reads -99 degrees...
On different forums I read that the temperature sensor is removed from the system, one website says from 2005, another says from 2008. My car is from 2007.
I read that the connector for this sensor goes directly to the front SAM, so I want to check the cable for defects but I don't know whether the system should even read something from the temperature sensor.
Sometimes the scan tools don't display proper values, or values for sensors that don't exist. With iCarsoft specifically, -99 value means sensor is not present based on what I've seen. However its possible due to MY, your car still has the temp sensor. Thus the -99 would imply no signal (suspect damage wiring or sensor or SAM).
And before I'm taking apart all kinds of stuff to check the cable, I would like to know whether the sensor is even present haha. So it can be that the value is read even though the sensor doesn't exist, or the cable is broken or something.
When I take off the connector, the pressure readout on the iCarsoft drops to 0, the temperature stays at -99.
Ok just to close this thread. I finally have the AC working. I replaced the pressure/temperature sensor with no effect. The temperature still read -99 degrees Celsius. So I checked the wiring going from the sensor to the front SAM. This was all perfect, no broken wire. I saw some corrosion on one of the connectors on the SAM so I took the whole SAM apart to clean it but this also didn't solve the AC not working.
Then I went on a trip to Paris and I noticed that the AC would blow cold air for 1-2 seconds and I smelled that typical cold AC air. So I suspected the suction return hose connected to the AC pump. These hoses have a tendency to delaminate from the inside, so the pump sucks a vacuum in this hose but it sucks it closed immediately. I replaced the hose (about 150 dollars) but when I cut it in half, the old hose turned out to be just fine. So this also didn't fix the AC.
Then I read out some stuff with my iCarsoft i980 and I saw that there's also some AC stuff in the front SAM, and there I got a error 9028 Component A9 (compressor) or lead has short circuit to ground or open circuit. I knew the wire going down to the pump was fine because I already checked this. I googled and found this forum https://mbworld.org/forums/gl-class-...-9006-a-2.html about a code 9006 with the same description.
Now when I begun this repair, I got a wrong pump (wrong number of belt-ribs) that was specifically for Mercedes (brand Valeo). It was the wrong one so I bought an aftermarket pump from the brand Nissens. This was a universal pump for multiple car brands. It turns out that Mercedes needs to have a diode placed in the pump control valve (or the small pump wiring harness). The Nissens pump did not have a diode in the wiring harness, the Valeo pump did. I replaced the Nissens harness for the Valeo one and then the AC worked!
I hope someone finds this particular thread helpfull
Geez im having the "no ac" issue as well. I replaced my compressor along with the pressure temp valve and still nothing. The sensor you replace was it the one below the coolant return tank?
Geez im having the "no ac" issue as well. I replaced my compressor along with the pressure temp valve and still nothing. The sensor you replace was it the one below the coolant return tank?
Yes, the part number is A0045429018. Mine turned out to be okay. Which brand compressor did you get? try to read the fault codes from the front SAM. If you also have the short circuit error, maybe you have the same problem I had.
Yes, the part number is A0045429018. Mine turned out to be okay. Which brand compressor did you get? try to read the fault codes from the front SAM. If you also have the short circuit error, maybe you have the same problem I had.
The sensor and compressor was purchased from Autozone and i did ran into the compressor problem since those car have (2) different kind but i managed to get the right compressor. I tested the compressor and there is no power going into the compressor. My dad ran a test wire direct to the pump and the ac started blowing cold. Reading your post you replaced the actual ac plug from your harness that connects to the compressor? Can you post a picture of what it looks like.?
Last edited by hellah fresh; Aug 4, 2021 at 08:15 AM.
The universal compressor that I built in which I bought from the autoparts store was a Nissens pump. Its cable harness did not have a diode soldered in. The Valeo pump that I bought before (but had the wrong number of ribs for the belt) was listed as ''specifically for Mercedes'' and did have a diode soldered in its wire harness. I just swapped the wire harnesses and the AC worked immideately. Before all this I also checked whether the cable going to the pump had a voltage and it did. It variated between about 11-13 Volts.
The wire harness is just like the one on the picture below. This is the one without the diode, the cable with the diode looked the same. The diode was under the black cable sleeve.
You mention that the compressor doesn't get power so I think your problem is somewhere in the engine wire harness going to the compressor.
Okay ima have to check out that wire to see what is up. Well my car sat for almost 2 years before i got it up and back on the road. The reason why my car sat was that the passenger seat module burnt out a fuse in the trunk and so we got that fix. My AC was working fine up until i parked it. Also do you have a link on where i can find that wire online be any chance?
My AC pump was stuck so I replaced the condensor, filter/dryer, expansion valve and the compressor. I also flushed the hoses and the evaporator. After filling and resetting the ''low refrigerant pressure'' error, the AC still doesn't work. I've checked the sensor readings with my iCarsoft i980, and everything seems to be okay, exept the refrigerant temperature sensor, this says that the temperature sensor reads a value of -99 degrees Celcius. The part number for this sensor is A0045429018. On ilcats.ru, where I can see all the part numbers for my VIN number it says that this is a pressure ánd temperature sensor. I thought this was strange so I replaced that sensor too, however the new one also reads -99 degrees...
On different forums I read that the temperature sensor is removed from the system, one website says from 2005, another says from 2008. My car is from 2007.
I read that the connector for this sensor goes directly to the front SAM, so I want to check the cable for defects but I don't know whether the system should even read something from the temperature sensor.
Can anyone explain? My VIN is WDB2110411B234664
Thanks a lot in advance!
Hi All,
I have different symptoms in my car but for the sensor A0045429018 my iCarsoft also displays -99 C. In my car AC works fine, no error code but the radiator fan runs at low power all the time when the engine is on. Even when the AC is off, outside temp is freezing and the coolant is cold.
I bought a new sensor but before building it in the car I just plugged the electric connector and it's still -99 C.
What's the story with the -99 C here?
Hi All,
I have different symptoms in my car but for the sensor A0045429018 my iCarsoft also displays -99 C. In my car AC works fine, no error code but the radiator fan runs at low power all the time when the engine is on. Even when the AC is off, outside temp is freezing and the coolant is cold.
I bought a new sensor but before building it in the car I just plugged the electric connector and it's still -99 C.
What's the story with the -99 C here?
Any help is appreciated.
Ádám
I have a document, that says sensor B12/2 (pressure ands temp) was used up to 31.5.2005, post that have B12 sensor for pressure. B12 pressure sensor has three connecting pins, B12/2 has four.
Fun fact, if you pull the connector from the sensor that is mounted on the pressurized system and plug it to the new sensor and turn the power on, you introduce atmopheric pressure to the control unit, which then locks the A/C as it thinks there's a leak in the system, and your A/C won't work!
I have a document, that says sensor B12/2 (pressure ands temp) was used up to 31.5.2005, post that have B12 sensor for pressure. B12 pressure sensor has three connecting pins, B12/2 has four.
Fun fact, if you pull the connector from the sensor that is mounted on the pressurized system and plug it to the new sensor and turn the power on, you introduce atmopheric pressure to the control unit, which then locks the A/C as it thinks there's a leak in the system, and your A/C won't work!
You are indeed a "super member" :-) Thanks a lot.
My 2007 sensor has 3 pins. I checked a 2003 car's and 4 pins. So the sensor is fine. I deleted the low refrigerant pressure code and it works fine.
Then just the original question remains, why does the radiator fan runs always... :-|
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