AC is currently not functioning and seeing the following diagnostic codes on my 1998 E300 TD, 58,000 Miles

B1231 - ECT Sensor (B11/4)
B1234 - Sun Sensor (B32)
B1459 - Series Interface (K2) Connection to instrument cluster(A1)

I have replaced Refrigerant Temperature Sensor, cleared diagnostic codes (and do not see any new ones)

AC Diagnostic actual values (original stop/running & after sensor replacement-stop/running) and Mercedes service are:

1-(37,37)(32,32)(29,29)
2-(37,40)(30,30)(33,33)
3-(40,40)(34,34)(26,23)
4-(40,40)(34,34)(26,22)
5-(54,55)(33,34)(28,14 up to 19)
6-(83,84)(37,up to 66)(82,81)
7-(00,00)(00,00)(07,17) if this is 1.7lbs then pressure has dropped from fill of 2.6lbs and AC may have a large freon leak.
8-(52,55)(32,32)(40,54)
9-(05,05)(05,05)(05,01)
10-(4.5,4.5)(6.0,6.0)(3.5,3.5)
11-(4.3,4.3)(4.3,4.0)(3.9,3.9)
12-(4.2,4.2)(4.3,4.3)(4.2,4.2)
20-(0.0,0.0)(0.0,0.0)(0.0,6.0)
21-(00,06)(00,06)(00,06)
22-(00,00)(00,00)(00,00)
23-(00,00)(00,00(00,00)
24-(11.5,13.0)(11.2,11.3)(11.6,12.6)
40-(71,71)(71,71)(71,71)
41-(34,34)(34,34)(34,34)
42-(72,72)(72,72)(72,72)
43-(152,152)(168,168)(168,168)

Learned a couple of things doing searches:
Didn't know how to clear codes - just hit both auto buttons at the same time.

From other threads it appears that I need a:

Refrigerant Temperature Sensor part number: 210 830 05 72

I have replaced sensor but am concerned that diagnostic value # 7 = 00. Shouldn't this number be greater than that? I am not seeing any diagnostic error codes at this time. If Freon was low wouldn't I get a diagnostic error code?

I brought the car to the local Mercedes dealer this morning.

I asked Mercedes regarding a freon diagnostic error and they told me in 1998 there were no sensors for freon. Mercedes diagnostics:

"Verified that A/C was blowing warm air, recovered R134a from A/C system, only pulled 0.02ibs of R134a, this indicates a leak in system, pulled vacuum, recharged A/C system to 2.20lbs of R134a. Also installed A/C dye into system, when A/C blows warm air again customer to return for further diagnosis & repairs."

Have you read this thread, particularly page 2?

Under dash panel panel under steering wheel has to come off. Sensor is located up high on the center console on the driver's side.

Len

Guess I didn't look enough. Thanks for you help. Now to find the part.

I thought that maybe if I reset HVAC computer I would get some cool air.

It still blows hot air though. No codes on HVAC computer now.

With the new part in hand, you'll at least know what you're looking for. That helped me to find it. I missed it the first couple of times I looked.

Len

Len, been underneath now looking for where the sensor plugs in for about one hour now and cannot find it. Is it to the outside of the vehicle (using the steering column as my center point) or toward the inside? Is it more towards the back or the front of car? Is it high up closer to the top or low? Can you please give me a point of reference? Thanks in advance.

It's up high on the center console, I think almost where the dash and the center console come together, but more on the console side. It's been a year and a half since I did mine, but as I recall, I may have had the same problem finding it as you are. Had to look more than once. Do you have the new part in hand? That helped me find it along with following some wires to it.

Just think how much easier it will be next time.

Len

Found it! Noticed the removed part is slightly different but same connector. Part number on removed part is one number off. So I started car and still warm. Any suggestions Len? I have reset diagnostic codes and currently have nothing but FF (I am guessing this is fine).

210 chassis climate control problem

Did you reprogram the unit as I described on page 2 of the above post, i.e. where you have to add 16 to the number shown?

Len

Len, Just reprogrammed it. Will try taking it for a drive and see what happens.

Test drove vehicle. AC still not running cold. It is not running hot though.

Brought vehicle to MB this morning. I have posted results above.

MB has not leaked Freon and values are same as previously noted above. MB in Sarasota, FL & service department was excellent. The only place that I could find the refrigerant temperature sensor last week was at the Fort Meyers MB dealer. Just an FYI relating to customer service and my experience there. The customer service representative there was a pompous a&#%& and for that reason along I would never return to that dealership. The parts person on the other hand was polite and pleasant to deal with.

In conclusion it turned out to be the evaporator coil. The freon leaked out in a matter of a few weeks. This is sad as the car has only 58,000 miles on it to see this go. I had the same issue with an E320 with 79,000. Before these two owned two MB diesels (purchased new) that ran and ran and were sold well into the 150,000 mile range with no real problems. I guess that's why MB is not scoring too well anymore with Consumer Reports eh? I wonder how the Germans automakers feel now that the Japanese vehicles are on the average scoring higher than their vehicles. I guess maybe its time for a Lexus.