R129 Air Con fault codes - help

[IMD]

Hi all,

I recently had my air con on my 1997 R129 re-gassed and it was blowing really cold. It hadn't worked for almost 3 years and I'd never got around to sorting it.

One week ago, I had the battery replaced and since then, the EC light has been coming on (have to press it for maybe 10 seconds to get it to turn off) and it just isn't very cold, sometimes warm!

I'm wondering whether the battery disconnect has affected the system or perhaps having no gas for so long has meant that it is now leaking?

I saw a post about checking codes using the air con unit diagnostic mode - Set the temp to 22º, press REST for 6 seconds and then go through the numbers.
The results (numbers) that I got were as follows and I wonder if anyone knows what some of these mean? Results are the figures given on right of each test information below:


01 In-car temperature sensor °C 27
02 Outside temperature sensor °C 23
03 Left heat exchanger temp. sensor °C 34
05 Evaporator temperature sensor °C 34
06 Coolant temperature sensor °C 73ºC
07 Refrigerant pressure bar 05º8
08 Refrigerant temperature sensor °C 33
09 Not assigned -- 08 ºC
10 Blower control voltage Volt 080
20 Auxiliary fan control current mA 00
21 Engine Speed x100 RPM 000
22 Vehicle Speed km/h 000
23 Circuit 58d (% of batt. Voltage) % 000
24 Battery Voltage Volt 12.3
40 Software status 02
41 Software status 03
42 Variant Code 1st numerical value 03
43 Variant Code 2nd numerical value 6-C
50 Not assigned 34
51 Not assigned 22
52 Not assignd 10ºC
60 Roof OPE/CLO CLO
61 Left side air outlet, knurled wheel 4.1
potentiometer Volts
62 Vacuum actuator 46, feedback 3.7
potentiometer Volts
63 Center outlet, knurled wheel 4.1
potentiometer Volts
64 Vacuum actuator 47, feedback 3.7
potentiometer Volts
65 Right side air outlet, knurled wheel 4.0
potentiometer Volts
66 Vacuum actuator 48, feedback 3.7
potentiometer Volts


Any help would be greatly appreciated.

Thanks

Ian

 

[IMD]

I'm aware that No 7 is the important one, the refrigerant pressure. Not quite sure what 05º8 means? It looks like a 05 (then degrees symbol), then 8.

 

[lexman8]

Parameter 21 says zero RPM. Was the engine running when you took these readings? If not, repeat them with the engine on.

Can you clarify parameter 07? At idle, I'd expect a pressure of 5 to 10 bar depending upon outside temperature, etc. When working normally, parameter 05, evaporator temperature sensor, should read about 2 to 5°C.

The EC light normally comes on when the refrigerant pressure is too low so you may have a leak or, more rarely, a faulty pressure sensor. Note also that if the EC light is on because a fault has been detected, the aircon will not work again until the fault code is cleared and the system has been reset.
_

 

[bing]

If you've read parameter 7 correctly at 5.8 bar then it seems theres (holding) pressure. Parameters 5/8 seem high.

What you pulled are sensor values. You need to go through the diagnostic mode and read fault codes, delete and reset. If still not functioning after reset focus on the codes that shows up again.

See here :https://www.youtube.com/watch?v=fO7i_Zj_hJo

Fault codes are shown if you click view more.

Hope that helps!

 

[IMD]

This is the No 7 reading today, with the engine running

 

[IMD]

Parameter 5 read 27 degrees at idle with cold engine, but the temp drops slowly, 25 after a couple of minutes

 

[IMD]

Thanks guys, I used the YouTube clip and found the codes and cleared them. The codes that were stored were as follows:


241 Refrigerant Level
416 Coolant Circulation Pump
417 Left Duovalve (Water Valve)
419 A/C Compressor Electromagnetic Clutch
459 Serial Interface Connection (K2) to Instrument Cluster

I cleared the codes, so will see what happens. I expect I'll need a top up of gas again. maybe it is leaking. I will get the pressure checked this week.

 

[andy27168]

The gas pressure if fully filled should be if I am remembering correctly should be in the region of 11-12bar system running. Not sure what pressure the low pressure switch cuts out at, but mine had a leaky condenser but would retain enough pressure to keep the EC light out, which again if I remember correctly was a similar pressure as what yours is showing now. Mine was a 202 but with climate control which has the same control unit as your SL.
A good indication of the system working correctly is that the two fans in front of the radiator will cut in and out as the refrigerant pressure fluctuating in normal use will switch them on/off at varying speed, if the system hasn't worked for a while then check that these fans freely rotate and are not seized as one mine was.

 

[Iqbal7]

Can I ask what machine is required to check these values. I have a W204 with radiator fan running constant, the aircon pressure sensor is suspected. I would like to check the values.

 

[OneForTheRoad]

Can I ask what machine is required to check these values. I have a W204 with radiator fan running constant, the aircon pressure sensor is suspected. I would like to check the values.

try taking off the battery earth for a while and reconnect . sometimes a loss of power resets things back to normal .