R Reg SL320 Evaporator Temp Sensor Replacement

[SW10_driver]

Hi All -

I have just replaced the evaporator temp sensor on my SL320, since it was reading 40 degrees previously and the EC light had come one. The temp is now reading 23 and is within range of the other temperature readings. Unfortunately the EC light is still on and the air con is obiously still no working.

Does the climate control need to be reset in any other way or is there any way of getting fault readings other than holding down rest and going through the individual readings?

Thanks for your help in advance.

Regards,

Ed

 

[SW10_driver]

Hi Again -

After digging round in the internet and other fora, I have found what I was looking for. I am posting below in case any other R129 owners from 9/95 onwards, require this information.

Regards,

Ed

CLIMATE CONTROL FAULT DIAGNOSIS - SL FROM 9/95

1. IGNITION : Position 1
2. Temperature selector wheel : "LO"
3. Within 20 seconds press the REST and DEFROST buttons simultaneously for more than 5 seconds.
4. The LED in the RECIRCULATE button flashes and "dI A" appears on the display.
5. Press the AUTO button until all DTC's are displayed and recorded.
6. The current faults are displayed first, then the intermittent faults. "END'" is displayed when all codes have
been displayed.
7. To erase codes press AUTO again, "dEL" will be displayed. Press v and ^ simultaneously for more than 5
seconds. The display will then show "---". Press AUTO to cancel the erase.
8. IGNITION : OFF to end the test program.
FAULT CODES - 129 Chassis from 9/95

DTC Readout Description

026 CAN Bus Communication
226 In-Car Air Temperature Sensor (B10/4)
227 Outside Air Temperature Sensor (B14)
228 Heater Core Temperature Sensor (B10/2)
230 Evaporator Temperature Sensor (B10/6)
231 Engine Coolant Temperature Sensor (B11/4)
232 Refrigerant Pressure Sensor (B12)
233 Refrigerant Temperature Sensor (B12/1)
241 Refrigerant Level
416 Coolant Circulation Pump (A31m1)
417 Automatic A/C Monovalve (Y19)
419 A/C Compressor Electromagnetic Clutch (A9k1)
420 Closed (Idle) Throttle Speed Increase
421 Auxiliary Fan Control Module (N65/1)
422 Serial Interface Connection (K1) to Instrument Cluster (IC)
423 Switchover Valve Block (15 connection multiplex) (Y11)
459 Serial Interface Connection (K2) to Instrument Cluster (IC)

 

[DubW129]

Where is evap temp sensor?

Hi, is the evaporator temp sensor located driver or passenger side in a RHD uk car? any details of what you have to strip back in order to get at it? as much detail as possible appreciated as have zero experience with this type of thing. I gather believe this is an easy enough job as regards "do it yourself" help much appreciated.

 

[SamT]

The evap temperature sensor can be accessed from the passenger side [on a RHD car]. If you look above the toeboard on the passenger side, you will find a near horizontal plastic panel, with screws attaching it to the bottom of the carpet-covered lower dash panel. If you remove the screws, you should be able to remove the panel.

If you then lie on your back through the open passenger door across the seat and footwell, so that you can look up into the under-dash area, you will see and/or find by touch the evap temp sensor, mounted on the LH side of the big plastic box above the transmission tunnel, behind the radio. [You could dismantle further and take out the carpet-covered panel, which is attached by screws sunk into the carpeting along its upper edge, but it isn't really necessary.]

The sensor is a push clip fit into the box and has a short flying lead, to a connector on the wiring loom under the dash. It will take you longer to find it in the first place, than to change it, because its uncomfortable and awkward, but fifteen minutes should see you done.

 

[television]

As SamT but if anyone needs the info I can send it,and the self check info done in the control panel

 

[SamT]

Having perhaps missed the point of SW10 driver's original query, another source of frustration in this area can be the refrigerant temperature sensor. The earlier cars are not fitted with it, I think that if you have the later control panel, you will also find one of these on the top of the filter/drier.

IIRC these were modded a long while ago, because of moisture penetration problems. It may be worth checking to see if you get an improbable reading there. unfortunately changing the sensor requires pumping down and re-gassing.

I did read somewhere that it is a redundant feature, as it's failsafe ability to derive a refrigerant level indication and so protect the compressor is already carried out by the pressure sensor. However it will definitely stop the a/c and light the EC light, unless fixed.

f you clear the fault codes, the a/c will work for a very short while and then cut out, but the delay before cutting out is much shorter than with a dodgy evap sensor and it needs the fault clearing every time, before it works again. I guess the delay just allows the system to validate the fault signal as "genuine".