98 S500 AC COMPRESSOR
 

98 S500 NO COLD AIR, AC COMPRESSER WILL NOT TURN ON. FUSE IN MAIN BOX IS GOOD, WITH A SET OF GAUGES HOOKED UP AND PRESURE IN LINES AROUND 95 lbs THERE IS IS PLENTY OF R134 THERE
ANY THOUGHTS THAT MIGHT HELP?

Did you pull the fault codes?

Read the procedure here: http://www.eclassbenz.com/node/27

The site is for e-class cars but the procedure will be the same for your 98. Perform parts 1 & 2 then post your findings.

98 S500 AC Compressor
 

Thanks Bob,
This is all new to me,but willing, and do have some skills.
Hope I did this right.
Error codes read Eb1 227
EB1 23
E FF
Fault Codes
1. 72 6. -40
2. -40 7. 4
3. 110 8. 58
4. 111
5. 64

98 S500 106.000 Mi
Love my car.

Error Codes:

B1227 Outside temperature indicator temp sensor (014)

B123 (didn't get the last digit) could be:

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)

E FF means no more error codes found.

Of those codes, I believe only 1232 or 1233 would be the only ones that would prevent the compressor from engaging. I'm definitely not an A/C expert, so I'm sure someone will correct me if I'm way off base. :)

For the real time data: (Assuming all temperature values are in deg F.)

#1 is inside temp: 72 (probably OK)
#2 is outside temp -40 (an improbable value. Sensor is bad. B1227 code above)
#3 is left heater core temp: 110 (OK)
#4 is right heater core temp: 111 (OK)
#5 is evaporator temp: 64 (probably OK if compressor is not running)
#6 is engine coolant temp: -40 (an improbable value)
#7 is refrigerant pressure in bars: 4 (probably OK if compressor is not running)
#8 is refrigerant temperature: 58 (probably OK)

98 S500 AC Compressor
 

Thanks for the help.
Any other thoughts as to why compressor does not turn on? I did check the compresor plug seems ok.


jlb

can you go read out all the digits of that eB123 code? That would help a lot.

98 S500 AC Compressor
 

I am sorry, I should have said in my last post. It was Eb1 231
Thanks,
jlb
98 S500 106.000 Miles

OK, B1231 is the engine coolant temperature sensor. That would make sense given that real-time value #6 reads -40. If that sensor is bad, I would expect that your aux fans would come on at high speed every time you turn on the ignition. Can you tell us whether or not they do?

98 S500 AC Compressor
 

Yes they do, about 15 sec after the car is started up, every time. I am refering to the fans at the front of the car. I was wondering about that, an going to address that next.Sounds like both are related to the same problem. If it is the coolent sensor, were is it located?

Thanks

jlb
98 S500 Black 1006.000 Miles

Sounds like your coolant temp sensor has gone bad. If the engine management system can't get a reliable coolant temp, it goes into kind of a fail safe mode and kicks on the aux fans at high speed to prevent the engine from overheating.

Regardless of whatever other problems you may have, you probably want to replace that sensor. It's very easy to get to. Pull off the smaller plastic cover on top of the engine. The sensor sits smack-dab in the middle of the area under the cover. It looks like a big bolt with two wires coming off of it.