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560SL Heating Problems

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6 replies [Last post]
Member
goconnor's picture
Richmond, CA
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Joined: March 9th, 2000

Posts:
25

Vehicles
2006 SL500

On my 1988 560SL air does not come out of the center nozzles. I'm thinking that a vacuum module doesn't open or close, so the air instead comes out of the defroster vents. No air comes out at all no matter what the temp or setting. Also, when the heater is set at maximum temp it's warm but not hot. The auxilliary recirculating pump at the firewall was replaced - could the mono valve be malfunctioning?

Thanks for your help!

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Anonymous
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Anonymous's picture
acc system

Hi Geof It sounds like you have two problem,first your veh had a problem with the defroster vent control lever behind the cluster it would brake not allowing it to change from defrost to center vents.or blend the air flow.On your heat i would check the mono valve to see if it is stuck most of the times the rubber diagram would rupture and you would get to much and uncontroled heat.joeym

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goconnor's picture
Richmond, CA
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Joined: March 9th, 2000

Posts:
25

Vehicles
2006 SL500

Come on - someone out there must know something about these problems?

Any thoughts?

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Peter Guenther 1's picture
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653

Quote:
Originally posted by goconnor
Come on - someone out there must know something about these problems?

Any thoughts?
If you dont like the answer go to your dealer and let them diagnose it!

Former Member
rdanos's picture
Larose, LA
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Joined: May 22nd, 2003

Posts:
127

Vehicles
1986 560SL
2000 SL600
Heater problem

I have a 86' 560 SL and had a similar problem. Remove the cover under the Glove compartment after removing the glove compartment. Find the manifold for the vacuum lines that control the modules. Find the main line from the engine and install a make shift vacuum sourch. A vacuum pump from a A/C friend works fine. Put a vacuum gauge inbetween the pump and manifold. Turn the ingnition keys on and press the selector switch each one at a time. If the gauge show low vacuum pressure that is you faulty module. If the manifold does not work at all the selector switches may have come loose behind the wood panel. Have fun.

rdanos
86' 560 SL

Anonymous
Guest
Anonymous's picture
vac leak

The previous diag is a start.There several vac elements that operate that system.A leak in any one of them will cause erratic climate control operation.A simple diag method is to take the car out with climate control on,push the throttle to wide open for a while.I f you notice the air coming out of the vents changes volumne or direction or vent location then you have a faulty element.You can also access the vac element block and check them individually as previously described.

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goconnor's picture
Richmond, CA
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Joined: March 9th, 2000

Posts:
25

Vehicles
2006 SL500

Thanks for the replies - I have 3 other Mercedes all diesels and have had similar problems. I'm new to the 560SL and hope to fix it myself. The dealer charges are high to ferret out these kinds of problems.

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