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560 sl
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5 Posts
Discussion Starter #1
I own a 1988 560 SL.
The car is great condition. I've been working some
bugs out of it.
The car produces heat when parked and when driving
for the first 1 or 2 miles. Then the air is luke warm.
On a cold day this is not enough heat.
It's still warm in the car but no "hot" air,
even on "Max" setting.
Any advise?
 

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600SEC
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8 Posts
My wifes car is doing a similar thing. If I mess with the connections to the aux water p...

My wifes car is doing a similar thing. If I mess with the connections to the aux water pump (the electric one for the heater) it works for a while. I think a bad wire to the electric heater pump or mono valve.


Try disconecting the power to the mono valve. This need power to stop the heater so unplugining it is the same as max heat.

Marco.
 

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1986 560SL
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1 Posts
Randy-Dallas-560SL

I just recently replaced the radiator (BEHR) and I am experiencing the same problem. Upon further inspection, I realized that the auxillary fan (electric fan) is functioning improperly. The auxillary fan comes on as soon as I start the car, not when the engine temp. reaches a certain level as it should, thus preventint the engine from reaching the proper operating temp. This is caused by either a bad (stuck) thermostat or a bad auxillary fan switch. The auxillary fan switch can be found on the top side of the engine behind the radiator (green, has two connections, one "one-prong" and one "two-prong" connection). Now, as to how you determine if the switch is bad or the thermostat is stuck, I don't know. I'm a light-weight when it comes to reparing a Benz. I've had this car for 10 years and I have a very reliable and REASONABLE mechanic that does all my work. So I'm just going to take it to him. Hope this helps. Let me know what you find out!
 

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560 sl
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5 Posts
Discussion Starter #4
Re: Randy-Dallas-560SL

I just recently replaced the radiator (BEHR) and I am experiencing the same problem. Upon further inspection, I realized that the auxillary fan (electric fan) is functioning improperly. The auxillary fan comes on as soon as I start the car, not when the engine temp. reaches a certain level as it should, thus preventint the engine from reaching the proper operating temp. This is caused by either a bad (stuck) thermostat or a bad auxillary fan switch. The auxillary fan switch can be found on the top side of the engine behind the radiator (green, has two connections, one "one-prong" and one "two-prong" connection). Now, as to how you determine if the switch is bad or the thermostat is stuck, I don't know. I'm a light-weight when it comes to reparing a Benz. I've had this car for 10 years and I have a very reliable and REASONABLE mechanic that does all my work. So I'm just going to take it to him. Hope this helps. Let me know what you find out!
 

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Registered
560 sl
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5 Posts
Discussion Starter #5
Re: Randy-Dallas-560SL

I just recently replaced the radiator (BEHR) and I am experiencing the same problem. Upon further inspection, I realized that the auxillary fan (electric fan) is functioning improperly. The auxillary fan comes on as soon as I start the car, not when the engine temp. reaches a certain level as it should, thus preventint the engine from reaching the proper operating temp. This is caused by either a bad (stuck) thermostat or a bad auxillary fan switch. The auxillary fan switch can be found on the top side of the engine behind the radiator (green, has two connections, one "one-prong" and one "two-prong" connection). Now, as to how you determine if the switch is bad or the thermostat is stuck, I don't know. I'm a light-weight when it comes to reparing a Benz. I've had this car for 10 years and I have a very reliable and REASONABLE mechanic that does all my work. So I'm just going to take it to him. Hope this helps. Let me know what you find out!
 

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560 sl
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5 Posts
Discussion Starter #6
1988 heat

I Don't work on this car myself.Thank you for your input.
I found that if you shut off heat for a few minutes and then put it on max, you get max heat.
If you back it off you'll get luke warm air.
You have to shut the heat off again to reset it and then you'll get max heat again.
In another words it's max or luke warm,
and only max after you shut it off for amoment.
No temp controled heating.

Anyway it's a great car, my Dad left it to me
and I love it. I fix it one problem at a time.
I runs great and it's in very good condition.

Thanx, Bill
 

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1986 LWB 300GD 6-2
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64 Posts
Did you ever fix your problem ?
Mine is doing the same.
Cheers Soeren
...


Did you ever fix your problem ?
Mine is doing the same.
Cheers Soeren
 
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