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Hi,

I am wondering if anyone can help with directions in how to replace the heater blower in my 1972 280 sel4.5. I am also replacing the heater controls; any help will be much appreciatted...


Thanks!

Juan
 

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1972 Mercedes Benz 280 SEL
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56 Posts
Did you ever get a response to your question? I have to replace the blower motor on my 1972 280 SEL 4.5 and need help.
 

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1972 Mercedes Benz 280 SEL
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The dash is out from the dash wood restoration. What I need help on is what else needs to come out - do I have to drain coolant, disconnect hoses, etc? Does the whole heater system with "Behr" on the front of it have to be removed?
 

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If memory serves me right it lives on top of the heater box requiring r/r of the heater box assy. You want to be sure it needs to be replaced before getting at it. If the box is out then reseal the heater valves and look really closely at the entire heater assy for any additional issues. Seems like there were some heater hoses that need replacement from time to time.
Bill
 

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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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The Behr unit, the AC, needs to come out too. You'll need access to a totally free and clear front end of the car. Same thing with the speedo cluster - take it out for easier access.
 

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I didn't have to take out the seats or the instrument cluster, but just about everything else comes out. It was like 6 hours out and 6 hours in. And as my memory serves me, the heater box needs to be taken apart with some caution to access the blower motor. If not the heater/air doors will get messed up... and yes, check those valves as long as you have the whole thing out. Good luck!
 

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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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6 in and 6 out? It took me about 40 hours, all told. I had to do it over 2 days. I first took it to a local guy to have it replaced, and he refused - LONG job.

Taking out the seats and speedo isn't NECESSARY, but it makes things a heck of a lot easier to do.
 

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1972 Mercedes Benz 280 SEL
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Before tackling this job, I did some checking on electrical connections. I removed the plug to the blower switch and determined that there is power there. I jump a couple of connections on the plug to see if that would run the blower, and it did not. This leads me to conclude that the problem is not with the switch. So, from what I can tell, that leaves a resistor and the blower motor. Where is the resistro located, and could that even be a problem? Thanks.
 

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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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If memory serves, the resistor is part of the switch. Can you send voltage directly to the blower, to see if it spins?
 

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1972 280se 4.5 Silver/Maroon
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Took mine of the other day and the switch has power in and three wires for power out . for the tree speeds, so I'm assuming the resistors are down at the motor somewhere. If they were built into the switch would just have one wire for out.
 

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1972 Mercedes Benz 280 SEL
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I removed the plug to the switch, turned the ignition on, and identified which female prong receptable had power. Then, I ran a wire from the prong receptable to each of the other three prong receptables one at a time. Should this have sent power directly to the fan? The fan never came on, so I concluded that the fan is the problem or the resistor, if it isn't part of the switch. Hence the question about whether a resitor problem could keep the fan from turning on.
 

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1972 Mercedes Benz 280 SEL
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I am still "kissing the rattlesnake" as another member said, with my never-ending blower motor replacement project. Everything is disconnected per the Mercedes service manual, but now I don't see how the heat exchange unit can come out without removing the a/c condensor unit. Does it need to come out, too?
 

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1972 Mercedes Benz 280 SEL
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This just gets better all the time. I just got back from the auto parts store and asked them for a kit to drain the a/c system. They don't have one. Plus they told me that if my perfectly-working a/c system is drained of the Freon which it probably has, I won't be able to return it to the system but will have to convert the system to 134 requiring me to replace the compressor. Can this be true?
 

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1972 Mercedes Benz 280 SEL
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Heater blower motor has been successfully replaced. Everything is back together. However, if I had to do it over again, I'm not sure I would. It is that difficult and time-consuming of a job.
 

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1985 380sl
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Hey guys! Has anyone found a higher power AC fan that pushes more air out than the original fan motor for the 108 bodies?
Thanks!
 

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1972 280SEL daily driver. 904 Dark Blue with cognac interior. euro 4.5 engine
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I assume you do in fact mean the AC fan, not the heater blower (which is the topic of this thread). I have replaced my AC fan with a 60's vintage Ford Mustang if memory serves me correctly. Same exact motor except for price. It blows the same as the original. What I have done to improve performance is:
  • sealed all gaps/holes in the AC duct with the good foil duct sealant tape .... better airflow
  • converted to R-134
  • removed the original condenser/fan and replacing it with a modern aluminum cross flow condenser and larger pusher fan. This turned my AC from marginal to COLD. I was amazed at the difference this new condenser made.
 
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