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  #31  
Old 07-07-2003, 03:44 PM
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It should. Is the key on? AC doesn't have to be.

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95 S420
91 300SE
87 300SDL
83 300SD
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  #32  
Old 07-07-2003, 04:10 PM
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O.K...The top one (green) does turn on the aux fan with ign. on. Is this my pressure switch ??

What does the one below do ?
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  #33  
Old 07-07-2003, 04:22 PM
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I have little diffirent settings, but your green is for the aux. fan...the fact that the fan works fine if you jumped it means either a defective switch (the green) or the pressure does not get to the point to activate the fan (low system pressure, bad compressor etc..., or the weather not hot enough to make the pressure builds up....
the other switch (down) is the compressor activation switch...it truns on the compressor if there is enough pressure (low but not very low)..and it cuts if the pressure getting very high..but it will connect back once pressure gets lower than the highest point...this extra protection was added after '86...so I do not know whether you have updaed one or not...
If you wait enough after turning the AC, the aux fan (low speed) will be activated eventually...if the system cools down nicely, this means the switch might be defective...
good luck
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  #34  
Old 07-07-2003, 04:34 PM
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The white rectangles contain the sockets of the wires that must be connected with a jumper to make the aux. fan turn on.

The green switch (temperature switch) has been superceded by MB, with the red switch, a few years back. Different pressure/temp curve on/off points.
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  #35  
Old 07-07-2003, 04:49 PM
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Yes, jumped the white things.

Pressure is 155 high side and 45 on low side. See my very first post. Don't think low pressure is a problem. What is considered HIGH ??

My temp gauge (Coolant) never really gets over 80 C so I can't really tell if it goes on by coolant temp alone.

Is is suppose to go on anyway with the compressor running ? If so, it is not.

The lower one has me intrigued though. If defective, and pressures are ok, what would be the effects.

If it's disconnected what will the effects be ??

Lastly, can these sensors be change without losing Freon ????
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  #36  
Old 07-07-2003, 05:12 PM
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The lower one is the pressure switch which would disconnect the compressor clutch if you were to be very low on freon (protective of compressor, since oil circulates with the refrigerant).

In the eary receiver/dryer you could remove one of those switches w/o losing freon (but I can't remember which one). I can't believe your receiver/dryer is one of the eary ones (unless someone searched one out) and therefore you would have to evacuate/recover before you replaced either switch.
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Last edited by jbaj007; 07-07-2003 at 05:33 PM.
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  #37  
Old 07-07-2003, 06:02 PM
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Quote:
Originally posted by alan911
My temp gauge (Coolant) never really gets over 80 C so I can't really tell if it goes on by coolant temp alone.
Seems like you have other problems. The gauge pointer should be above 80C. I say that like I'm a tech. I know I had bad thermostats on the SD and SE when they weren't reading above 80C most of the time and shot over 100C when it got really hot.

Sixto
95 S420
91 300SE
87 300SDL
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  #38  
Old 07-07-2003, 06:17 PM
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Well I say that 'cause most of my driving is around town. Not much on the freeways.

It does move up a little bit over 80 C. when the A/C is functional and on and sitting in traffic. But most of the time it hovers just a hair below 80 C.

Don't tell me I have more problems. ..........Had the car since '89 and 80 C, 78-79 is about where it's been all these years. Even today, it's over 100 out. Geeeze..., you mean this isn't normal ?????

Since the other car is a oil cooled 911, I'm really a high temp freak. So I always watch temps.
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  #39  
Old 07-07-2003, 07:03 PM
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I don't mean to cause alarm. Maybe it is normal. My temp gauge is pretty much stagnant in the winter and hyperactive within a range in the summer. I thought all MBs were like this.

Are you saying that thermostat's been in there for at least 14 years?

Owning an 86-87 603 is reason enough to be a high temp freak

Sixto
95 S420
91 300SE
87 300SDL
83 300SD
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  #40  
Old 07-07-2003, 07:27 PM
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The Thermo. 's been in there since I've had it anyway. My temps never really vary much. Never, ever overheat. Not that I've noticed anyway.

Only have 103,000 mi on it. I got it with 42,000 on it. So I put about 61,000 on it in 14 years. (4400 annual average) Helps to have 2 cars I guess.

80 C. is about 176F or so. I always thought that most cars ran about 180F. So I guess that's why I thougt 80C was normal and never questioned it. If around 80 is out of line, I need to know.

Oh.... I blew out a belt once and that motha soared up the scale real quick like.
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