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  #1  
Old 11-14-2002, 04:54 PM
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Join Date: Nov 2002
Location: Orange County, CA
Posts: 95
Unhappy W124 Blower always on

Today I replaced the following on my 1987 300D ACC system:

1) Push Button Control Unit
2) Vacum change over valve
3) sampler motor for inside temp sensor
4) all 7 vacum actuators

I also checked the temperature sensors by following procedures with an Ohm Meter according to 83-604 in the service manual (Checking electronic components of the automatic climate control) and all sensors are in the specified ranges.

My blower motor is always on! When I hit the 2 fan speed buttons on the PBCU, the speed will increase a bit or decrease a bit. When I hit the 0 button, the fan still remains on.

Any suggestions?
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  #2  
Old 11-14-2002, 05:15 PM
it leaks, its german
 
Join Date: Mar 2002
Location: raleigh nc
Posts: 1,111
blower regulator is stuck. check it



Joe
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Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364
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  #3  
Old 11-14-2002, 06:16 PM
Registered Diesel Burner
 
Join Date: Aug 2001
Location: Northern Virginia
Posts: 2,911
Was the pushbutton control unit new or somehow refurbished?

I had the same problem, also the A/C would run in the OFF position. It was the pushbutton control unit - I was able to fix it by resoldering the circuit board at every junction.

Ken300D
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  #4  
Old 11-15-2002, 02:38 PM
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Join Date: Nov 2002
Location: Orange County, CA
Posts: 95
Blower Regulator Chaeck

How would I check the blower regulator without having the special socket box?
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  #5  
Old 11-15-2002, 02:40 PM
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Join Date: Nov 2002
Location: Orange County, CA
Posts: 95
Refurbished Unit

The Pushbutton Climate Control Unit was refurbished with a 3 year warranty. How do I check to see if it is defective? The old unit behaved the same ie. blower on when 0 is depressed.
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  #6  
Old 11-15-2002, 03:25 PM
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Join Date: Nov 2002
Location: Orange County, CA
Posts: 95
Original Thread

W124 Climate Control Mystery
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  #7  
Old 11-15-2002, 06:03 PM
it leaks, its german
 
Join Date: Mar 2002
Location: raleigh nc
Posts: 1,111
you gotta pull the damn moter but, once it's out, and unplugged from the motor, check the input signal from the PBP, with it off the voltage should be zero, 5v high (I think it 5, anyway, it'll show no votlage in off and some in any other place. :-) ) With the PBP panel input unplugged, if you have voltage out to the motor then its fried. (the blower regulater that is) the 202 regulators are real good at this one)



Joe
__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364
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  #8  
Old 11-15-2002, 06:55 PM
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Join Date: Nov 2002
Location: Orange County, CA
Posts: 95
Update

I tested the old Push Button Climate Control Unit by applying 12V to pin 13 Left and Ground to pin 10 Right. I then pressed the 0 button and measured the voltage at pin 12 Left (which goes to the blower control unit N29). The voltage was zero. When I pressed any of the other buttons and pressed the high fan button, the voltage jumped to about 7.6 V.
I believe this tells me that the blower control unit is fried. I will remove it and test it next.
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  #9  
Old 11-19-2002, 10:22 PM
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Join Date: Nov 2002
Location: Orange County, CA
Posts: 95
Regulator was Problem!

I replaced the blower control regulator ($250) and the blower works fine!
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