88 300 SEL. Converted to R134a before I purchased it. Let's ignore that for now and just focus on the fan issue. A/C works well when I'm driving, but when I'm at idle, it barely feels colder than ambient air. Low side pressure is 45. I just had the car checked for vacuum leaks and was told there were none. (I read a post that mentioned that a large vacuum leak could cause warm air at idle). Auxiliary fan never seems to run, even at idle in 100 degree california weather. I took it off and attached it to 12 volts and it works fine. The temp gauge never reads over 100 celsius so I understand why the high speed fan mode doesn't come on. But it seems to me that the low speed fan should come on in such hot weather at idle. I have the green topped three pin sensor coming off my drier. I know JimF makes something to turn on these fans at a lower coolant temp, but I haven't seen any for the w126 with the three pin sensor. Any other thoughts or a better way to diagnose what the problem is? Would it hurt anything to just have the low speed fan on all the time and if so has anyone done it? Am I wrong to assume that the problem is the fan; is there something else that would cause warm a/c at idle?

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Eric Zacharias

'88 300 SEL
'64 Ford Falcon
'99 Infiniti QX4