My 91 300E only blows full heat out the defrost vents when the defrost button is pushed in. All other parts of A/C control work well and correct. A/C blows cool when required. Compressor works as it should.

What is causing the full hot heat out defrost???? I've reviewed other post without answers. Is there a valve not pulling a flap correctly? Defrost does work, but in the summer during rain, the full heat coming out the defrost vents is terrible.

In defrost mode the controller sets the heater valve to full heat and engages the compressor to dehumidify the air, regardless of temp control wheel setting. I think between having the heater and AC both running full tilt, the heater will win.

Sixto

yeah, it's a drag when it is raining out and it becomes humid and steams up the windshield. To clear the windshield you have to crank the defrost and then all you get is a blast of hot air. Makes it even hotter inside the car. Never liked this feature of the CC on our MB's.

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Frank
84 500SEL EURO 101K ( JUST LIKE MY 1ST WIFE. GLAD TO GET RID OF HER! )
85 300D 310K (sold)
90 350SDL 184K sold
83 300D 118K (sold)
88 300E 153k (sold)
93 400E 105K (sold)

That's what the "other" A/C setting is for - the one with solid arrows pointing both up and down. It will blow chilled air from the A/C up towards the windshield. The defrost setting is for use in the winter when there's ice or snow to melt - hence the heated air.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Also when using the double arrow A/C button close the center vent but leave the side ones open and more air gets to the windshield.

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

thanks, I see I'm not the only one. Nothings wrong then great.

Oh something's wrong, but it's with MB's design

Sixto

oh, my bad...

My understanding was that the button with both arrows meant that it woudl blow from the upper vents and also at the floor level. I misunderstood.

__________________
Frank
84 500SEL EURO 101K ( JUST LIKE MY 1ST WIFE. GLAD TO GET RID OF HER! )
85 300D 310K (sold)
90 350SDL 184K sold
83 300D 118K (sold)
88 300E 153k (sold)
93 400E 105K (sold)