2005 SL350 (R230) Aircon will Not Switch Off …

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WolfieS

Member
Joined
Oct 1, 2013
Messages
40
Location
Westbury, Wiltshire
Car
2005 SL350
Hi,

Having posted last year that, following an accident – Aircon undamaged – my Aircon would not switch ‘on’ despite the switch in the Centre Console illuminating, I finally carried out some ‘back to basics’ fault diagnosis where it transpired that there was power going to the Aircon Compressor Clutch but the clutch was not engaging. Consequently, the compressor was changed.

However, this proved not to be a full resolution to my Aircon maladies … the Aircon Clutch did initially engage for a few seconds but then switched ‘off’ again and would then not operate. After pulling all the gas back out (again), refitting the old Temp/Pressure Switch (I had fitted a new one ‘just in case’) and refilling the system, the Aircon Clutch then sprang back into life and the Aircon started to work … HOWEVER, now the Aircon will not switch ‘off’.

When I press the illuminated Centre Console Aircon Button, the light goes off, then flashes slowly for a few seconds, and then illuminates again. The Aircon Clutch does not disengage – even when I switch the Climate Control ‘off’, the Aircon Clutch remains engaged.

If I turn the Climate Control up to max, the heat does increase a little but seemingly commensurate with the Aircon also operating. If I turn the Climate Control selectors to minimum, the fans increase (slowly) to half of full speed and that is as fast as they run in ‘Auto’. Moreover, I would not say that the car gets particularly cold. Almost as if the Aircon is not working at full efficiency.

Any ideas as to what might be the fault or how to proceed with diagnostics?

Regards

Wolfie Souter
2005 SL350, Westbury, Wiltshire, UK
 
IIRC the a/c will continue to run for a set period after being switch off. How long are you waiting?

Also the a/c is best left on continuously as it dehumidifies the incoming air and also keeps the a/c seals lubricated.

If the car isn't getting warm enough perhaps the blend flaps need resetting or the duo-valve needs attention (not sure which system the R230 uses)

Would suggest getting the car on STAR and check for error codes
 
IIRC the a/c will continue to run for a set period after being switch off. How long are you waiting?

Also the a/c is best left on continuously as it dehumidifies the incoming air and also keeps the a/c seals lubricated.

Hi and thanks ... the a/c continues to run continuously (without cycling on-off) all of the time. When I attempt to switch the a/c 'off', the light flashes slowly and then illuminates again, ie, the a/c does not switch off - not for a second for the whole of the time that the engine is running. I appreciate it is good practice to have the a/c 'on' to lubricate seals; but, as it is 'on' continuously, my mpg is down by 4 mpg. Even if I switch the Climate Control 'off', the a/c remains 'on'. Oh, this issue only started when I had the a/c re-gassed after the new compressor was fitted.

Regards
Wolfie Souter
 

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