When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello guys. I just acquired 2000 E320 about 2 weeks ago and getting to know the car each day. At the same time,
it's a Mercedes, so what I know from the past sometimes (most of the times?) does not apply to these cars when
it comes to, such as repair and maintenance. So I ordered some manuals from evilbay and waiting for it to be deliver.
So please bear with me.
My problem right now is that driver side AC is not cold. Pass. side seems no problem at all. Nice and cold, but the
driver side is warm on start up, get cooler but not cold as pass. side. Since I do not have manuals, I don't even know
the proper pressure for the AC, so haven't hook up the gauge or troubleshoot any of the component.
Is there like a valve to control the air flow or temperature? My previous car had a control valve that goes bad every so often
and needed a replacement in order for both side to work. Is Mercedes have something similar?
With a STAR diagnostic system or equivalent you can perform a test of the flapper valves under the dash. If you do not have a good diagnostic system, get one. You'll need the 38-pin adapter to access the diagnostic connector under the hood in the fuse box.
It is possible you have a bad duo-valve under the hood. If it is the duo-valve, you should see error code B1417 or B1418 when you run diagnostics as described below. Also possible you have a failed flapper valve or just a vacuum line break.
Flapper valves are actuated by vacuum; the hard line can break near the duo-valve located left rear under the hood. If the line is broken, just trim and repair with vacuum line. (Duo-valve is the double-can device in the background. That adjusts the flow of hot coolant into the heater cores.)
The HVAC system has its own onboard diagnostics. The following I copied from previous posts so others gathered the info first and then shared so give credit to the ones before me. READING SENSOR VALUES
1) Turn ignition on. Simultaneously press down and up arrow push buttons until the pre-selected temperature setting of “72 °F” is displayed. Press the AUTO push button.
2) Press REST push button for more than 6 seconds. The display window will alternately show “01” and an in-car temperature of “72 °F”, or “LO” if there is an open circuit, or “HI” if there is a short circuit.
3) By pressing the driver side temperature push button, the next ascending test step is displayed. By pressing the passsenger side temperature push button, the next descending test step is displayed. Press REST push button to exit reading sensor values mode.
01 = In-car temp sensor
02 = outside temp sensor
03 = left heat exchanger (heater core) temp sensor
04 = right heat exchanger sensor
05 = evaporator sensor
06 = coolant temp
07 = refrig. pressure in bar
08 = refrig temp sensor (23*9 = 23.9deg C)
09 = nothing
10 = Blower control voltage (great for evaluating blower controller problems)
11 = emissions sensor (B31) e.g. 3.1 = 31.v
12 = sun sensor 4.2 = 4.2v
20 = aux fan control 6.1 = 6.1ma (max 10ma)
21 = engine speed
22 = vehicle speed
23 = Circuit 58d e.g. 99 = 99% of battery voltage
24 = BATTERY VOLTAGE e.g. 12.5 = 12.5v
30 = left rear air conditioning heat exchanger temp sensor (not all vehicles; obviously)
31 = right side
32 = rear evap temp sensor
33 = blower control voltage rear 0.8(MIN) – 6.0(MAX)
34 = left rear temp selector
35 = right side
38 = software status e.g. 37 rear air conditioning
38 = hardware status e.g. 37 , rear air conditioning
40 = control module version software status
41 = control module version menu hardware status
42 = control module variant code 1st number
43 = variant code second number.
To pull error codes perform the following. Be advised an error code will appear as "Eb1 232". This corresponds to (E)rror B1232.
1) Turn ignition on. Press down arrow push button until “LO” is shown in A/C-heater control panel temperature display window.
2) Within 20 seconds, simultaneously press REST and defrost push buttons for more than 2 seconds. The Light Emitting Diode (LED) in the recirculated air push button will blink and the display window will show “di R”.
3) Press AUTO push button repeatedly, recording each DTC, until all DTCs are displayed. Permanent malfunctions are displayed first. See DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION tables.
4) If no permanent malfunctions are stored, the display window shows “En d”. Press AUTO push button again. Intermittent DTCs will be displayed. Intermittent malfunctions are recognizable by the degree (°) symbol displayed along with the DTC (example: “04 °”).
5) If no intermittent malfunctions are stored, the display window shows “En° d”. Proceed to ERASING DIAGNOSTIC TROUBLE CODES.
Erasing Diagnostic Trouble Codes
1) After display window shows “En° d”, press AUTO push button once again. Display window should show “dE L” (delete).
2) To erase DTCs, simultaneously press down and up arrow push buttons for more than 5 seconds. The display window should show “- –“. If not erasing DTCs, press the AUTO push button. The permanent DTCs will again be displayed. Proceed to EXITING DTC DISPLAY MODE.
Exiting DTC Display Mode
Simultaneously press down and up arrow push buttons until the pre-selected temperature setting of “72 °F” is displayed. Turn ignition off.
DTC error codes list:
B1226 – In-car temperature sensor (B10/4)
B1227 – Outside temperature indicator temperature sensor (B14)
B1228 – Heater core temperature (B10/1)
B1229 – Heater core temperature (B10/1)
B1230 – Evaporator temperature sensor (B10/6)
B1231 – ECT sensor (B11/4)
B1232 – Refrigerant pressure sensor (B12)
B1233 – Refrigerant temperature sensor (B12/1)
B1234 – Sun sensor (B32)
B1235 – Emissions sensor (B31)
B1241 – Refrigerant fill
B1416 – Coolant circulation pump (M13)
B1417 – Duovalve (Y21y1), left
B1418 – Duovalve (Y21y2), right
B1419 – Electromagnetic clutch (A9k1)
B1420 – Idle speed increase
B1421 – Pulse module (N65)
B1422 – Series interface (K1) connection to instrument cluster (A1)
B1423 – Switchover valve block (Y11)
B1424 – Activated charcoal filter actuator (A32m2) open
B1425 – Activated charcoal filter actuator (A32m2) closed
B1432 – Non-USA DTC
B1459 – Series interface (K2) connection to instrument cluster (A1)
B1462 – Wide open throttle (WOT) position signal: diesel engines
FWIW, here's the B1232 code I received a few weeks ago for the refrigerant pressure sensor. I will put the car in the shop for this one...
AC low-pressure line fitting is located mid-length of the engine on the right-hand side while standing in front of the car. The AC high-pressure line fitting is located at the upper-right of the radiator fan shroud while standing in front of the car. Remove the screen over the electric fans. In the upper-right of the fan shroud you will see a small plastic cover pressed on to the shroud. Carefully pry it off (brittle after a few decades) and you will find the high-pressure schraeder valve there.
Ref the radiator electric fans; one is motor driven and the second fan belt-driven off of the first fan. Yes, the drive belt can break and cut cooling significantly. Just rotate one fan with your fingers and both should turn. If not, just pull the fans out and replace the belt with OE or OEM.
Last edited by bbirdwell; Jul 3, 2023 at 03:53 PM.
Thanks guys. I thought I went through sticky and did the search, but guess it wasn't good enough.
I'm still waiting on my manuals but I can perform the on-board diagnostic so wish me luck. I'm hoping it's something small/easy. Hoping for the best, preparing for worst.
Cool from the passenger side vents and warm from the drivers side vents is common when the refridgerant is low, but it can also happen if the duovalve is acting up.
Just ran a diagnostic and came back with B1233 and B1234. Ref. temp sensor and Sun sensor.
Just how hard is it to change the sun sensor? Went online and according to the web info, it's at middle top dashboard (unless this info is wrong).
Can I just pry that out with plastic pry bar that's use to take the door panel off? Or does it have to squeeze out from under the dash?
I'm still waiting for the manual to come in, so most of my knowledge is from here or the web.
Thanks Plutoe. I checked the vacuum line that was posted but that's not broken. So I assumed it was those error code unit that's need of replacement.
However, when I ran the diagnostic, #3 & #4 had 14 degree difference (94 vs 80) , and Ac pressure of 14 so I'll try refilling it first, than tackle the duo valve next?
I'm still waiting on the manual as the seller sent me the wrong one (Saab). He's sending me the right one, but will be couple more days before it gets here.
Anyway, driver side is still warm, so I thought I'll charge it up just the little. 1 Bar is is pretty big compare to Psi and since you
mentioned 17 Bar in the previous post. Of course, I'm still waiting on my manual, so I still haven't hook up the gauges yet. Or
any other diagnostic(s).
What worries me is that Ref. Temp Sensor. Looks like I need to evacuate the system before I can get to it. Maybe I should evacuate
first, change the sensor and re-fill it.
Just quickly jumping in to share my AC experience last week. My 1999 E320 has been near perfect performer the past decade. Last week when I drove it, the EC light stayed on and I was unable to override it. In previous years, I might have needed to toss a can of r134 in every couple of years. With the EC light on, this meant the compressor was OFF and unable to draw in and circulate r134.
Several days passed as I plowed through how-to on various MB forums. Oh, I also was unable to enter the diagnostic part to display the fault codes which made things more challenging.
FINALLY after dozens of button pushing (something like press and hold EC and REST.....or EC and DEFROST....or DEFROST and REST.... one of them worked, just as I was about to give up. EC light went out and the DEFROST was blinking. Whatever, in any case compressor was now operative again. Out came the r134 and plugged into the low pressure port. I turned on the climate control diagnostic part that displays AC pressure/temperature. Toggled to "7" and noted 7 bar.....then 9.....then 10 etc.
It has been holding at around 14 bar the past week and I'm a happy camper, thrilled that my baby was purring smoothly again. (What's this....Plutoe is picking up tab for pizza?)
Thanks for the info raymond. My EC light is out, so I'm guessing that AC system is working.
Today, went to the car and took another reading. As before, #3 is at 94, #4 is at 87. Difference is smaller than before, but there is a difference. Forgot to
post it before, but #8 which supposed to be refrig temp sensor is showing E, which I guess correspond with my error code of B1233. Only other worry I
have is #24, which I have at 11.6. I bought a brand new battery the other day as the battery came with the car was dated 11/18 and wasn't sure of the
condition of it (it did died and won't start the engine. Reason for me to get another reading). I took the reading without starting the car, so maybe that's
why the reading is low? I threw away my previous reading, so not sure what was the reading before.
Anyway, still waiting on the manual. In the meantime, reading all I can on the web, including stickies.
Just wanted to update as some of you may have wondering what was wrong with my AC.
That manual finally came in, but still learning how to use them. In the meantime, since I have a manual in hand and if anything gone wrong, I can always refer to the shop manual, so decided to tackle the AC problem. Hooked up the gauge and everything look good. pressure is little on low side, so decided to add some R-134a. I've used straight 134a, not the ones with any sealant in it. If I have to, I was going to use the can with a dye in it later. But my first step was to fill it with proper amount of 134a. Just got the car like month ago, so I need a baseline on everything I do. Surprisingly, I had, according to the on-board diagnostic, 14 bar pressure, but took almost a pound of 134a. I can't be sure exactly how much, but it took more than 12oz because can of 134a I had came with 12oz. It took one can and little more. Wasn't that much, but definitely, more than one can. Yes, I know if you subtract the weight, I can tell how much I used, but I didn't weight the can before use.
Anyway, after re-fill, my AC is blowing ice cold. Pressure is at steady 16 bar, and it's blowing colder air than the DD driver I had, which was 2004 Lincoln LS, which got replaced with this E320 due to parts availability (It was basically Jaguar with Lincoln body, They only made those from 2000 to 2007, so good parts are very hard to come by) .
When recharging AC systems, I use a kitchen scale set in grams to measure the amount of refrigerant I am adding. As an example, with fitting installed, the full can will measure at 475 grams. After bringing the system up to the proper pressures based upon outside air temperature, the can may measure 250 grams. I then note in the maintenance log that 225 grams of refrigerant were added to a system with 1000 grams capacity.
FWIW, I go to pick up my '99 today. Compressor failed so it and other parts replaced. The car is 24 years old so I'm not complaining too loudly. Since I just got my '05 out of the shop two weeks ago for a large repair bill, and now adding this repair bill, I told the owner I expect to see my photo on the wall with the annotation, "Customer of the Month".
I've read through this thread and still coming up short on understanding how to handle diagnostic code B1232. I have a 2000 E430 which I've been having issues with the AC system. I ran the diagnostic and it came back with one code B1232. The compressor cycles on and off rapidly. I assume this is due to the B1232 code.
I have two questions
1.where is the location on the refrigerant pressure sensor?
2. What is the normal refrigerant pressure ( screen 7 reads 2 bar on my system)?
All I can tell you is 2 bar is way too low. You need to recharge the system. But first, you need to find out why you need to recharge it. Yes, I'm pretty sure you have a leak, but from where is the question.
Now, you need to hook up pressure manifold to get accurate pressure reading, but since you don't even know where or what to look for, before you do any (more) damage, take it to professional and have them diagnose. Those recharge kit you buy at auto store only read low side pressure, and those cheapy gauge is not accurate. I once bought a recharge kit with those gauge and it was off by almost 10 psi (I do have manifold but I left it at my work so i've use the gauge that was on the can). I actually had to release some refrigerant.
Recharge the system, and run the diagnostic again. You don't have to top it off. Just add some and see if the code still there. But if you really don't know where the port is, or what to look for, take it to professional or ask a friend who knows how to work on car. They should have an idea where or what to look for.
Thank you for the reply. I do know where the port for recharging is located ... Both high and low pressure on driver side of vehicle. Low side next to engine and high side next to radiator.
My concern is the location of the refrigerant pressure sensor. But I suppose with pressure being so low that could be cause for B1232 diag code
Following up, I hooked up the manifold today and read high and low pressure sides. The pressure on the high side was way too high which was causing the compressor to cycle on and off. When the compressor kicked on, high side pressure would go above 400psi and the compressor would kick off. I relieved some of the pressure, freon, from the high side and monitored the pressure for both high and low. I purchased the vehicle a few months ago and the previous owner mentioned a problem with AC. Apparently they must have over filled the system. Diagnostic no longer shows any codes. Compressor is staying on full time with AC settings to low at highest fan speed and shuts off when temperature increased as it should. AC super cold again, all fixed. Thanks for the support !
Last edited by Dacrambo; Feb 16, 2025 at 08:36 PM.
I'm not quite sure why only 2 bar. I believe it had something to do with the extremely high pressure on the high side. As soon as I relieved some freon from the high side, the compressor stayed on for more than 4 or 5 seconds. The low side pressure normalized while the compressor continued to run. Both high and low side pressures are within range for the ambient temperature now.
Last edited by Dacrambo; Feb 17, 2025 at 10:23 AM.
woooooh we are not being told the real and complete story----i just wish that the posters would tell the complete story and the truth as we all just waste our time with BS
Thats exactly what i did to a T. Hooked up manifold. Compressor would kick on high side would go into the 400s and kick off. I relieve some of the freon from the high side. Then compressor stayed on which brought the low side to about 35 PSI ~2.5 bar and the high side now being around 150 PSI ~10 bar. No BS about it.
Last edited by Dacrambo; Feb 17, 2025 at 03:11 PM.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
