Keeping the AC from coming on EVERY time I start car??

[chillcat]

I'm posting questions I keep thinking of based on my 91 500 sl, every time I start car the ac turns on, so I hit the button that turns it off, how do I keep this from constantly turning on? I have no idea how this ac system operates, way too many buttons/options for me.

[kknudson]

I'd have to go out and look, but there is an E/C mode. Economy (Makes sense in an expensive sports car, ya right)

Since I never use ti AC or rarely the heat, I just run it in that mode.

[Mike Miller]

I can only think you have a short that occurs when you hit the starter. It must only happen for that instant as I believe you said you can turn it off once the car is running. I have a '92 500SL. OFF is OFF until I turn it on. It never comes on be itself.

[chillcat]

Yes, Every time I start car, the "automatic" button lights red and AC turns on, it goes off if I hit "O" button--just under the automatic button. Any way to prevent this from automatically turning on?

[Ron MB]

Originally Posted by chillcat

I'm posting questions I keep thinking of based on my 91 500 sl, every time I start car the ac turns on, so I hit the button that turns it off, how do I keep this from constantly turning on? I have no idea how this ac system operates, way too many buttons/options for me.

Hey chillcat, I'm having the same problem 1991 500SL if you should find a soultion drop me line.

Thanks Ron MB
ron6802@tampabay.rr.com

[chillcat]

I sure will, how long have you owned your sl ? I've had mine about 2 weeks now or so. Anyone know where the audio amplifier is located?

[chillcat]

I went to MB today in Gainsville to order a keyless remote and asked a service guy about why the ac comes on everytime and he said it sounds like a wire issue--but to find the problem would not be worth the $$ unless I really wanted to fix it, I said naw, I'll live with it.

[bobterry99]

Originally Posted by chillcat

Yes, Every time I start car, the "automatic" button lights red and AC turns on, it goes off if I hit "O" button--just under the automatic button. Any way to prevent this from automatically turning on?

It's annoying but normal operation for the early climate control units to come on automatically. To minimize the annoyance, I suggest selecting the lowest blower speed and EC mode. If your controller is like mine, then on a startup the controller remembers those settings. Another solution is to remove fuse #10 from the main fuse box. That will disable the climate control unit.

[chad500sl]

I think the older R129 act differently than the newer ones. My 1990 500SL remembers whatever setting the climate control was on before you turn it off. For mine, if you push EC before off the next time you start the car it will be in EC. It would be nice if it would stay off, but EC with the lowest fan setting is close enough. Basically it will remember any setting except for off. Those wacky Germans...