Hi I have a 98 Mercedes e430 and the ac blows hot then cold off and on but more hot then cold! I had the system drained and recharged at a shop and changed the evaporator temperature sensor but still no luck! Please any help is appreciated!!
Also wanted to add every time the ac starts to blow cold there is a musty smell that comes out of the vents! Don't know if that has anything to do with it? I've been scouring the web tryna find a answer but nothing seems to make my symptoms
Hi I have a 98 Mercedes e430 and the ac blows hot then cold off and on but more hot then cold! I had the system drained and recharged at a shop and changed the evaporator temperature sensor but still no luck! Please any help is appreciated!!
1) When you say blows hot and cold, does it do this when you set the temperatures to LOW at both sides, or just when you set the temperature to say 70 degrees F ?
2) Does hot air blow from both left and right central vents ?
3)When it blow cold, does it blow cold about the same temperature from left and right vents ?
4)Does it blow warmer when you are idling at traffic lights?
5) When the engine is cold, and you start the car with a/c on, does it blow cooler than when the engine is at operating temperature ?
6) Does the hot / cold blow flip flop at certain rate or. random ?
Did you find error meaning and clear it?
Next time you enter hot cabin, display #7 , then start the engine and observe the changes for next few minutes while driving.
Heater will always overcome AC no matter what.
His core shows 57F with 138F exterior and 199F engine, what would be pretty good proof duovale is holding.
The AC is evidently working, but not enough or intermittently. We still don't know if the error was cleared and if it come back.
As you said, if pollution sensor triggers the alarm, it diverts the flow to recirculating via carbon filters.
But recirculation can be run only for limited time, or driver will die from lack of oxygen, so who knows what MB programmers made up for such situation.
Than if the sensor was read faulty, the computer has default programs for such occasion.
Problem is that defaults programs are unknown to car owners, so we can only guess or try by error.
My logic guess would be that with pollution sensor failure, the computer will "nag" the owner to take care about it... like killing AC for example
Come to think about it, the OP was also complaining about some musty smell. Do you think there is a small vial of stink gas hidden somewhere and released sparingly when the owner neglects his a/c maintenance and needs to be penalized ?
Ok so since I've changed the evap temp sensor the ac blows cool/ cold now as soon as car warms up. Now what I'm noticing is it only blows super cold when the car is in motion.
Also yes the code eb1235 keeps coming back even after I clear it.
Are you saying that the intermittent hot air blowing through the vents is not happening, and you are just having very cold air when the car moves but not so cold when the car is idling ?
You get very cold air regardless the temperature setting (after the interior reaches the desired temperature ?
Are you sure you installed the right part, and installed correctly ? If not. your evaporator can freeze over, and you get hot air due to reduced surface transfer. For example if your evaporator "actually" goes down to 32 Degrees F, but your evap sensor say it is 42, the compressor will keep on running till finally it catches up with the evap. temp sensor.
Maybe I miss something, but the 2 readouts you posted did not indicate any problem with evap temp sensor?
I still would advise you to check the pollution sensor, as we don't know how the error can affect AC performance and at this point that seems to be the only thing that can occasionally kill your AC.
The sensor is located somewhere under passenger side gutter, but I never had to see it.
Hopefully it is just dirty plug, so have can of MAF cleaner with you.
So you replaced the sensor only becouse somebody else did on different car?
Again, from your data did not look that sensor was bad and if AC started to work better it could be coincidence, or something else you did not even knowing.
I think you will never figure it out till you do proper troubleshooting.
Figured it was worth a try for a $10 part. I'll try to look for the emissions sensor and clean it like you said. Other then that what other trouble shooting should I do?
I wonder if your engine speed sensor #21 (rpm x 100) could be causing the problem. Wouldn't it shut down the compressor if excessive engine speed is detected (obviously your engine isn't spinning @ 440,000 rpm)?
10 bars (#7) @ 107 degrees (#8) would indicate compressor is off if system is charged correctly.
Well the readout was only 44 but was told in a previous post that it's supposed to be 4400 sorry for the confusion. It felt like the compressor was off cause the wasn't cold just normal temp.
In post #3 , Mr Boca stated engine was OFF when you did your FIRST reading of values based on #24 indicating battery voltage was at 11.8 volts. Yet #21 shows 32 or engine speed of 3,200 rpm! Values should be read at idle as I previously posted with a link on how to do it correctly.
I'm not positive but pretty sure there is a rpm cut off for the compressor. If your #21 sensor is giving sporadic high reading, this could be your problem.
BTW: I edited post #27 . Your compressor was off during last reading of values.
Yes that is what I was going to suggest that you check.
The RPM is derived from crankshaft position sensor signal to the ECM which is the supplied to the instrument panel, which is then passed to the climate control unit. It is used to determine when to turn the aux fans on (at idle, and how much, based on the refrigerant pressure sensor. If the aux fans do not run at idle the condenser will not cool the refrigerant and reduce the pressure. When you are at highway speed the fans do not need (and should not be) to turned on due to incoming air flow..
The climate control seems to send the voltage to the fan control unit but maybe the unit is faulty or the fuse is blown. Or maybe the fans are not working as they should.
Ok so since I've changed the evap temp sensor the ac blows cool/ cold now as soon as car warms up. Now what I'm noticing is it only blows super cold when the car is in motion.
^^^ This sounds normal. Air conditioner does not engages immediately after start up (there is a delay). Air temperature will be colder when car is in motion because there is more air flow thru the condenser and compressor will be turning faster with the higher rpm.
This statement is confusing. Is OP now saying air conditioner is no longer operating sporadically and is on all the time? As stated above, air temperature will be colder with car in motion.
The clutch for the compressor is electrically activated / deactivated by the Climate control push button module (N22). So the relay (mechanical or solid state equivalent) is inside the unit .
So I think there is something wrong with my rpm reading. When cruzing at 60 on the free way #21 is reading 6800rpm ? Would this affect anything? Also does anybody know where the emissions sensor is located?
Does your car cool well when cruising at 60 miles/hour ?
If so, , it does not seem to be affecting the compressor operation.
for emissions sensor, see attached. The emissions sensor just changes the way airflow is routed (recirculating air through the charcoal filters).
If I were you I would do the following:
1) reset the climate controller when engine is off by taking its fuses off , wait few minutes and reinstall them
2) Check the connector on the compressor for the compressor clutch. If the connection is intermittent due to contamination / corrosion, you may have intermittent clutch disengagement which would cause the compressor not to work. I am not sure if this would be detected as a fault eventually.
from my experience, the musty smell is "freon" and probably a bad evaporator.
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