My '95 E300D is at it again. Now that the cold weather is here the start of the Heater Fan blowing is delayed by a few minutes until the engine heats-up a bit. This is normal and I am aware of that. Yesterday however a new symptom started that sounds like it could be trouble.

Sarting the car when cold (outside temp at 32F), and after a few minutes of the fan not blowing (normal for this temperature), I would start hearing loud clicking sounds coming from what appears to be the KLIMA relay. After about a minute of clicking, the fan would than come on, and the clicking subsides to nothing. If I start the car while the engine is still hot, the fan starts immediately, and there is never any clicking.

I am not sure, as I need to experiment with this, but, I think that the clicking sound is only there when the Climate Control Unit is in "AUTO" Mode. I think that when its in Manual Mode i.e.: High or Low speed pressed on the Push Button, that the Fan starts right-away and there is no clicking sound prior to start-up. But as I said I am not sure if that's the case or not, I'll need to try it next time.

At this point I am not sure if the problem is the KLIMA relay itself, the Climate Control Unit, or something else. Any ideas?

Thanks

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

You may be hearing the switchover valve cycling through modes on startup, both of my W124s do that. If the clicking seems to come from the glove box, it's very likely the switchover valve.

Probably goes from off to air intake open to heat to mixed mode, three or four clicks.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

There are a couple of places that you can hear clicking. The blower speed module will click every time it changes speed. The pushbutton module has a couple of relays that are energized by the cold lockout swithc, but only in economy and normal mode, not in total ventalation mode.

The heater blower should not start in heating mode (in-car temp is lower than temp set on dial) below 33 C engine coolant in economy or normal mode. Heater blower motor should start after 33 C coolant temp is attained. If the blower is not starting, pull wire from the coolant lockout switch and ground it. If the heater blower starts after approximately 10 seconds, the themperature switch is faulty.

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Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

Peter,

The sound does come from the glove box area, [My car however has no glove-box] I never thought of the switch-over valve as being suspect. Does the fact that its clicking mean its defective? Is it normal for it to click for 30 Sec. or so before the fan comes on?

Michael,

After the initial cold start delay, the heater blower starts fine. Its just that it is preceded by this loud (approximately 20-50 Sec.) clicking sound that comes from somewhere behind where the glove-box would normally be, or from the KLIMA Relay. Not sure anymore which one, I will listen carefully next time.

Thanks

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]