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Registered
1979 280SL, 1984 280SL
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5,659 Posts
Discussion Starter #1
1991 350SD- Love the car, hate the Climate Control!

Here is my current state of affairs, and a new problem.

The HVAC in the car is generally inoperative. I have a new monovalve, new aux. waterpump, and a tested, used ccu currently installed. Here are the current performance parameters.

The blower will not shut off. It will operate at various speeds, but will not shut down. I have been told this is most likely due to the "porcupine" resistor. I have a replacment, but have not had the chance to install it yet.

The AC compressor does not run. I do not know if it is the clutch, or a failed compressor.

I have been able to get heat from the car, so I presume my new monovalve and pump are working.

Here is a new problem, that started today. The heat is on all the time! The recirculation switch has a red indicator light, that is newly flashing on and off, and whereever the temp wheel is set- nothing but hot air. A real problem with ambient temps in the 80's.

Ultimately, I need the system to operate as intended. I will settle right now for shutting the heat off.

thanks for the help!!!
 

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Premium Member
1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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1,026 Posts
Not much help, but, I had that similar situation happen to me once. The light on the recirc was blinking and I had full hot from the vents in the middle of the summer. It seems that no buttons could really do anything either. When I got home, I just shutdown the car and it has been fine ever since.

Couple of things to check on your fan speed issue...

1. You already are going down the path of the resistor...good.
2. Not sure if this is the same for the Gen1 cars but on my Gen2 there is a small air sampler motor behind the passenger side (right-most) vent. It sucks air across a temp sensor to sample cabin air temps and adjust the fan accordingly. If this motor is bad or the the temp sensor is bad, it can make your fan speed unpredictable. You get to it by removing the glove box liner IIRC.
 

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Registered
1979 280SL, 1984 280SL
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5,659 Posts
Discussion Starter #4
Thanks for that suggestion Foolio. WIsh I had a glovebox- it would make things easier! My car is equipped with a passenger side airbag.
 

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Premium Member
1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
Joined
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1,026 Posts
Shoot, for some reason I read your post as 300SD.

Airbag removal is not that bad on the passenger side. If I recall, you remove the kickpanel and there are two 10mm bolts that are up inside the corrugated tube. Requires an extension and as always unplug the battery for an hour before messing with the air bag. I think the procedure is laid out pretty well in the FSM.
 

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Registered
1988 420SEL, for sale
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317 Posts
Mine has a glovebox, but the sampler motor was low on the right kickpanel in front of the door, so maybe you can go in below the airbag? Test it first with the key on, and place a tiny bit of tissue paper against the inlet grill above the rear view mirror. If it pulls air, it will hold the tissue against the opening. My sampler motor was frozen.
 

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Registered
1979 280SL, 1984 280SL
Joined
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5,659 Posts
Discussion Starter #7 (Edited)
Good info, Thanks.

As soon as we have a day where it's not 90, or raining, I'll get ouyt and remove the kick panel to change the resistor. I'll try the tissue paper test once I get the blower to shut off.

I really can't wait to get the whole system functional again- it's the last hurdle!

And FWIW, I just went out and started the car, no flashing light on the recirc switch.
 
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