Mr. B

HELP... another A/C problem…




holy cow… if it’s not one thing it’s another…

after getting the blower regulator fixed and working like a charm for about a week… all of a sudden the A/C doesn’t want to make COLD air…

only blowing hot air now… when you first start up… it seems to want to work, it will start to get cold then just stop making cold air and only blows ambient temperature air.

ran these A/C diagnostic codes… now i think i have the conversions correct but not sure about #7 & #8...

1 - 37.… converted = 98.6*F……… in-car temp.
2 - 41.…………….= 105.8*F…….. outside temp.
3 - 15.…………….= 59*F………… heater core left
4 - 15.…………….= 59*F………… heater core left
5 - 13.…………….= 55.4*F……….evaporator temp. sensor
6 - 89.…………….= 192.2*F……ECT engine coolant temp
7 - E ………………= ??? I’m at a loss……refrigerant pressure in Bar
8 - 49.…………….= I believe this is *F….refrigerant temp. sensor

any clue as to what the “E” on number 7 means..??

also found these error codes through the A/C diagnostics: not sure if they are current or old codes from previous owner, that may have been repaired but not removed...

Eb1231 engine coolant temp sensor malfunction
Eb1232 refrigerant pressure sensor malfunction
Eb1234 sun sensor malfunction
Eb1459 ?? i can't identify
Eb1422 ?? i can't identify

i hooked up a gauge to the refrigerant input and it reads as if the freon is with-in the proper levels (high side of blue zone… green being low and yellow high, red danger zone on my gauge)

i’m thinking this might be the “evaporator temperature sensor” based on a search of the forum… i believe i might be on the right track, just want to confirm before i buy the part…

also any recommended sources for the part and/or a part number for a 1997 E320... i have purchased from autohausaz.com in the past with excellent results but they don't seem to have it listed under my years parts list for some reason... maybe i can call them...

any help is greatly appreciated… suffering in 100*F plus blk on blk MB


~ Mr. B ~

slk55lvr

Hey I am having the same problem as a couple of you guys, a big thanks to whoever posted how to read these sensors! Here's what mine just read:


1. 78
2. 76
3. 84
4. 82
5. 80
6.84
7. 01
8.76
9. 27
10. 2.3
11. E
12. 4.3

What does the "E" on number 11 signify?

Mr. B

okay, i’m only guessing now based on a little research… best to wait for the pro's.... but could the “E” be error (misread due to a fault of some kind in the system)…

#11 would be emissions sensor (B31), e.g. 3.1 corresponds to 3.1 volts

#7 = refrigerant pressure in bar, e.g. 01 corresponds to 1 bar.

i think this means your refrigerant pressure is running a bit low (01 bar, should be 10-25. it varies depending on how much compression is needed to cool your car). this probably means that you're low on refrigerant. you should get a recharge.

is your EC light stuck on permanently..??

if not it means the pressure hasn't yet dropped far enough to force the A/C compressor to shut off. note that MB air conditioning systems use variable pressure to provide the appropriate level of cooling as needed. this is helpful for fuel economy. but it makes it impossible to know for certain how much refrigerant is in the system based on pressure alone. often you can tell you're low on refrigerant by a hissing noise coming out of the center vents. the hissing is the sound of the refrigerant rapidly expanding to fill the evaporator. this only makes noise when you're low on refrigerant.

do you hear this hissing noise?

also have you noticed the fan just not blowing as hard as it use too..??
mine was only working to about the third bar then no increase in blower output even though the controller would display all the bars...
i had a bad blower regulator, one of the common problems... do a search for the "how-to" on repairing that part of it.

not sure if a recharge will make the #11 code better... it should be showing a voltage reading of some sort..??

need a pro..!! some one will answer soon i hope...

take care,


~ Mr. B ~

Musikmann

I think the #7 E refers to the refrigerant temperature in bars. If that sensor is functioning properly, you have too little refrigerant it looks like. But, as another contributor mentioned, it might also mean a bad evaporator sensor. Speaking from personal experience, you better hope that you don't have a bad evaporator!

lexrex on this forum wrote a nifty A/C diagnostics program; to use it, all you need are the codes you already have. The name of the thread is: A/C diagnostics instructions & analysis utility.

Hope this helps,
M

raymond g-

lexrex
+ diagnostic program
= here (scroll down)

okc329

These cars are noted for having a failure of this sensor which can be easily replaced from the drivers footwell. Not expensive and does not require any changes in coolant content. Make sure you get the revised part.

slk55lvr

Perfect, thaks so much for the help! My EC light is permanantly on and if that measures the amount of pressure then I need to recharge my coolant. I did get the hissing sound a while back but it's stopped now, but the blowers are still pushing as hard as ever. This is such a load off my mind, thank you so much for responding!

Mr. B

thanks Raymond… found that thread and the great utility, ran these results listed below… didn’t really solve my problem since i just repaired the regulator, so it’s blowing like mad, just not making cold air… i’m thinking i’ll try the evaporator temp sensor (since it's only $35) and we’ll see if that fixes it…maybe replace all the other sensors just to be safe if it doesn‘t fix it… heck, i don’t know what else to do…


results from scan:
Your climate control data has been received.
Your A/C system is working properly. The evaporator temperature is 13 degrees.
If your problem is air flow, rather than air temperature, it's likely that your blower regulator went bad. (not the problem, just replaced it)
Code B1231 Explanation: This sensor measures the temperature of your engine coolant. This reading is used to delay turning on the heater fan in the winter until the air is somewhat warm. The sensor is reporting an implausible temperature.
Code B1232 Explanation: This sensor measures the pressure of the refrigerant in the A/C system. It appears to be malfunctioning. If this sensor is defective, you may be able to turn your A/C back on by overriding it.
Code B1234 Explanation: This sensor detects strong sunlight and increases the fan speed slightly to compensate for solar gain. The sensor is located in the middle of the dash near the windshield. This sensor is not critical. Its failure would not interfere with normal A/C function.


Thanks,


~ Mr. B ~


your welcome… glad to help… this air thing is driving me crazy… mine was back to working fine this afternoon for some reason… seems to be intermittent. i’m going to just replace one sensor at a time until it’s all working fine again… don’t know what else to do… take care,


~ Mr. B ~