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Alex,
Your story is classic for a faulty evaporator temperature sensor, and the numbers confirm it. The sensor is located on the side of the evaporator case under the dash. You should be able to find directions for how to replace it online. Once you replace the sensor, everything should be back to normal.
Blake
Hi Blake,
AC blowing warm air. Here are the sensor values and error code for my 1999 E320. The EC light is not on.
sensor value:
1 – 94 – inside temperature
2 – 109 – outside temperature
3 – 93 – Left Heater core temp.
4 – 80 – Right heater core temp.
5 – 118 – Evaporator temp.
6 – 208 – Engine coolant temp
7 – 4 – Refrigerant pressure
8 – 132 – Refrigerant temp
Error code:
Eb1 232 – Refrigerant pressure sensor (B12)
Thanks.
98 E300. Sometimes starts cooling but warms up, or the fan stops. Codes are as follows:
1-93
2-84
3-66
4-66
5-139
6-136
7-21
8-159
Trouble codes: Eb 1227, 1231, 1234, 1235, 1459, 1422
Help is greatly appreciated.
Calvin,
Thank you for the beer. Your problem is a faulty evaporator temperature sensor (#5). It's reporting an implausible temperature. The A/C control unit recognizes that the temperature reported cannot be correct, and shuts down the A/C to protect the evaporator from freezing. The system ignores the sensor for the first several minutes of operation. That is why it starts cooling and then warms up. Replace that sensor and you'll be back in business.
Blake Cameron
Mike,
Thanks for the beer. You have a bunch of error codes. Did you get the controller used? If so, some of them may be left over from the car it was removed from. I recommend clearing the codes. To do that, go back into the error code mode and press & hold both AUTO buttons for a few seconds until it flashes 'eFF'. At that point you can turn the ignition off.
The compressor won't engage due to two of your error codes: B1232 and B1233. You'll need to clear the codes to find out if they're real (i.e. whether they come back.). Those codes correspond to refrigerant pressure sensor and refrigerant temperature sensor. The pressure can be bypassed. I can tell by the reading from that sensor (#7) that something is wrong. It's showing 0 pressure. Either your system is completely empty (unlikely) or the sensor has gone nuts. You can override that sensor by doing the following:
1. Switch the ignition on (position 2).
2. Set the left temperature to 'HI' and the right temperature to 'LO'.
3. Switch the ignition off.
4. While holding the 'REST' button, switch the ignition on (position 2). On the left side, 'P1' will flash and on the right side, a code will be displayed.
5. Press the 'EC' button twice so that the left side flashes 'P2'.
6. Using the right side red temperature increase button, add 16 to the value.
7. Press the 'EC button again to store the updated code.
8. Turn the ignition off.
The refrigerant temperature sensor cannot be overridden and needs to be replaced if the error code persists. Both of these sensor problems will prevent your compressor from engaging.
You do not have an error code for the A/C compressor clutch, which is good news as it indicates that the computer isn't even trying to turn on the compressor. This suggests a sensor/computer issue rather than a problem intrinsic to your compressor.
Regards,
Blake Cameron
Harold,
Thanks for the update. I think you're right that something got disconnected.
Blake
Hi Blake. Sent you some extra beer as I have a kinda weird case. I am a W211 guy but hoping you can help me out none the less. Having the weirdest thing happen with my car. I am able to get into my sensor screen and it seems to work just like you guys in the W210s but I can not pull the codes like you guys do. AC was warm on drivers side and cool on passengers. Replaced AC compressor (did this before finding your awesome site) and with new compressor and full AC…I am having strange readings still on my #3 sensor (the left side heater core) it NEVER is the same as the right and when driving it will come close but when I come to a stop light, I can literally watch it rise about 1 degree or even more per second up to the 50s. Left side AC feel will stay cool until the temp sensor goes into the 50’s, then I can feel a difference right to left. Step on the gas and drive and temp drops dramatically again.
Learned so much from you but I am really clueless on this one.
Any help for a frustrated W211 guy. E55 amg. Out of warranty and a DIY guy that hates the dealer.
Thanks again Blake.
1-22
2-22
3-53 (coolest it goes is 30ish when driving)
4-27
5-12
6-89
7-15
8-54
9-4
On the W211 if you continue to scroll up in the numbers you do come to some FF numbers but they didn’t make sense. here they are just in case. 1B 01 32 16 FF
Jim,
I’m not familiar with the W211. The general principles still apply.
There are two fundamental categories of problems that cause a right-to-left vent temperature differential:
1. Not enough A/C; or
2. Too much heat
It’s hard to tell exactly which category your problem belongs to. Your story of warm air at a stop and cool air while driving suggests that your A/C is inadequate. However, your sensor values are more consistent with having too much heat. Your issue may actually be a combination of the two.
Refrigerant flows from right to left through the evaporator core in the dash. If your A/C is borderline, the left half of the evaporator will peter out while the right keeps working. Even in a normal system, there will always be a small difference from right to left, but it should never be more than a few degrees. There are several possibilities for why your A/C might not be cooling adequately when stopped:
1. Defective compressor. The compressor has low-speed and a high-speed modes. Maybe your low-speed mode doesn’t work? It’s possible your new compressor is faulty.
2. Inadequate heat transfer at the condenser. Do your auxiliary electric fans in front of the condenser (radiator) work? If they’re not spinning, you won’t get any airflow through the condenser at a stop.
3. Low charge. You might simply need more refrigerant, although your pressure (#7) looks good.
Your heater core temperatures (#3 and #4) are unusually high, worse on the left. When the heater is off, the heater cores should register somewhere between the ambient temperature (#2) and the evaporator temp (#5). Your heater cores are warmer than the outside air — 53 degrees Celsius is about 130 degrees Fahrenheit. This means one of two things. Your sensors are wrong (doubt it), or your heater is stuck on. I suspect the latter. This “stuck heater syndrome” is common on the W210. Cleaning the duovalve usually cures the problem.
Your A/C will never be as cool at a stoplight as it is driving down the road. Perhaps the heater is sticking just enough to overpower the A/C at a stop but not while in motion.
I recommend that you check the easy things first, like eyeballing the condenser fans.
Here’s how I would investigate the heater: Start the car up cold in the morning with the A/C on. Watch the heater core temps while it’s parked in your driveway. You have a window period of a few minutes to follow the temperatures before the engine coolant warms up enough for the heater to matter. If the heater core temps are initially cold and equal, and gradually warm up on the left, you know the heater is on. If the left starts out hot and never gets cool, you know it’s an A/C problem.
Wish I had a more concrete answer for you. It’s just impossible to narrow it down to one thing with the limited information we get from the sensors. Let me know what you find out.
Blake