AC blow cool air then blow ambient

[Fast_car]

AC blow cool air then blow ambient
Here is the code from my 1999 E320 with the engine & A/C switched on.
Does it mean I have a bad evap temp sensor, where is this sensor located ?

Thanks

The AC temp was set as 72 per instruction and car was park in side garage while I took this value

1 = 75
2 = 73
3 = 80
4 = 78
5 = 143
6 = 85
7 = 06
8 = 76
9 = 27
10 = 1.1
11 = 0.3
12 = 4.3
20 = 3.2
21 = 32
22 = 00
23 = 32
24 = 11.6
40 = 164
41 = 85
42 = 40
43 = 136

[stevebfl]

Sure does. Unless you have some other reason for having an evap temp at 143 deg.

[Fast_car]

Thanks Steve

Can you plese let me know where is the Evap temp sensor locate, I remove the panel under streeing wheel, but still can not find it. My car is 1999 E320

Thanks
Tan

[pat201]

TAn,
How did you get the codes? I have a similar problem with my 99-E300TD. It happends after 5-10 minutes if I drive on highway or city. I had a brand new compressor + dryer installed a week or so ago. It worked fine just a day or two.
Thanks, PAT

[Fast_car]

Originally Posted by pat201

Tan,
How did you get the codes? I have a similar problem with my 99-E300TD. It happends after 5-10 minutes if I drive on highway or city. I had a brand new compressor + dryer installed a week or so ago. It worked fine just a day or two.
Thanks, PAT

the code from this link, does not know t's the same for your car or not, but the author said pretty much similar

http://www.continentalimports.com/ser_ic40142.html

Good luck

[pat201]

Tan,
I did the test. Here is what I have:
1 (In-car Temperature sensor B10/4) = 102 F
2 (Outside temperature sensor B14) = 112 F
3 (heater core temperature sensor left B10/1) = 111 F
4 (Heater core tempertature sensor right B10/1 = 109 F
5 (Evaporator temperature sensor B10/6) = 147 F
6 (ETC sensor B11/4) = 188
7 (Refrigerant pressure in bar) = 25 bar
8 (Refrigerant temperature sensor B12/1) = 138 F
9 (?) = 27
10 (Blower control voltage) = 5.3 V
11 (Emissions sensor B31) = 2.5 V
12 (Sun sensor B32) = 3.8 V
20 (Control current for auxiliary fan) = 21.1 mA
21 (Engine speed) = 420 rpm
22 (Vehicle speed) = 0 km/h
23 (Terminal 58d) = 32%
24 (Battery voltage) = 13.1 V
40 (Software status) = 164
41 (Hardware status) = 32
42 (?) = 08
43 (?) = 136

I also did the second test called DTC Memory (when you set the left temperature selector HI and teh right at LO and then you press REST and EC buttons for more than 5 seconds). The only code displayed was E on the left hand side of the screen. Then after I pressed AUTO to get the many codes I read about, the only code displayed was FF on th eright side of the screen.

I would appreciate any suggestions.
Thanks PAT

[engatwork]

(Outside temperature sensor B14) = 112 F

Where are you from?

[pat201]

Detroit

[pat201]

After doing some reading of former posts I believe The Evaporator Temperature Sensor (part number 210 830 0572) has falied. I was able to locate it (just above the gas pedal) and remove it (from the console wall) by depresing the snap fits which hold it in place. I used a Clark digital mutimeter to see what kind of resistance measurement I get. The value I read is 1225 Ohms. Is this value indicating a failed sensor?
Thanks PAT

[Arthur Dalton]

The Evap sens is a negitive thermistor [ meaning as temp goes up, ohms go down].
So , for testing, you have to compare your ohm reading to a temp chart .
To simplify this , if you take the termistor out and get it to a stable room temp of 20C/68F, it should read between 11.5 and 13.5 K ohms to be ballpark.

However, if the sensors value ever get LESS than 2.5 K ohm [ which is your case ] , then the Control unit sees this as a shorted sensor and automatically shuts down the compressor after approx. 2 min. It will then not restart the compressor until the engine has been shut off and restarted .. but this cycle just start all over again, as your complaint states

so, sensor change should rectify this short cycling problem.
You may want to do the temp/oms test anyway...

[pat201]

Arthur,
Thank you for your reply.
Indeed I removed the Evaporator Temperature sensor from the car. I re-measured the sensor resistance inside the house (room temp ~ 75F) and I got the reading of 1,100 Ohms (1.100 on the 2 kOhm scale). It appears it got bad. I will get a new one tomorrow. I will post the results afetr the new one is installed.

[pat201]

I replaced the old Evaporator Temperature Sensor (part # 210 830-0572) which was reading about 1,100 Ohms with a brand new one (part # 210 830 0772). The new one has a resistance of 2,600 Ohms. See attached pic - the new design is the lower one.
However this not fix the AC. Although the vents start blowing cold air for a minute or two they return to the old habit of blowing ambient air.
I know that there a few more sensors (e.g. the one mounted on the drier and the two relays of the aux fan). Any suggestion on further troubleshooting is appreciated.

[stevebfl]

You didn't happen to add a little refrigerant before working on the electrical. Your pressure (25bar) seems high for 420 rpms. What is it key on engine off. There is a common occurance of pressure switch problems but I've also seen too much refrigerant cause your problem and there was no other problem.

Actually both instances a can or two of refrigerant was tried, before he brought it to me.

[Paul_Dierze]

I have the same problem and bought the part but I can't get the cover off...I took out 4 screws and nothing budged. I still have that wierd screw under the steering column to take off but how?

Thanks,

Paul

[pat201]

No I did not added any refrigerant at all. Do you suggest to release some of the refrigerant to lower the pressure? If so to what value I should lower it? (now is 25 bar)

Paul, the cover is held in place by the following fasteners:
3 screws (2 located on the fabric portion of the cover on left and right side - where you have your knees when you drive, which the third one is new the hood release handle.
Then you have also a plastic nut located between the accelerator pedal and brake pedal, and a plastic philips screw which holds the lower vent grill attached to the console.
Finally there are also 3 snap-fit fasteners - you need to pull the cover towards the driver with some force. Do not use screw driver to pry it because you may damage the fabric. Good luck.