W124 Heater Blower

[124BST]

The heater blower in my 124 estate gave up the ghost last week so I stripped it down and after bench testing it and condemning it to the scrapyard, I replaced it with a new unit.

Annoyingly and quite oddly however, it still isn't working! I'm therefore looking for suggestions as to where to go next... The fuse is fine and has 12 odd volts at it when the heater is turned off but this drops to zero as soon as you turn the knob. Is this an indication that the heater control is faulty?

Would appreciate any advice as don't really want to strip the centre console down if I'm chasing my tail... I have also seen heater blower regulators advertised but cannot find the location of this unit in order to inspect. The car is a 93' 300TD, pre facelift/OM603. Thanks

 

[124BST]

Should have mentioned that it has no air con or climate control - just the most basic heater option.

 

[grober]

Mercedes-Benz W124 HVAC Resistor Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article

 

[optimusprime]

Grober thank you for that , this is another one for the book .You learn more every day on the forum ..I would do just the same as 124bst, and swop out the squirel cage and motor and not look under the base for the resistor .

 

[124BST]

Thanks for the link. I have a completely different blower motor however (see photo) and the resistor isn't located in this compartment.

I have a feeling that this might be it (2nd photo) and it's located behind the fuse box up under the windscreen... Bad news is that I have no idea how to remove it as I can't see any fixings and it's hardly easy to access!

Would appreciate any suggestions - resistor, heater control, and have even read about a link to a switch in the ignition barrel?

Thanks

 

[124BST]

Resistor:

 

[grober]

I am beginning to wonder if the car didn't have an an aftermarket air con system fitted at some point. Some of these were Mercedes dealer approved/fitted post purchase DIAVIA comes to mind.
W124 Diavia A/C Systems | Mercedes-Benz Owners' Forums

if so these guys may be able to advise?
http://www.ac4cars.co.uk/

 

[124BST]

Thanks for the suggestion but no aircon fitted or climate control of any kind - just the most basic setup with the blower and vent knobs and two temperature wheels.

 

[tron]

'Old on lad: you have twelve volts at the fuse until you close the switch and then the voltage falls to zero. Yes?
If so and the fuse doesn't blow, the problem is a loose, dry or corroded connection UPSTREAM of the fuse.
Once the circuit is obliged to supply current, the resistance of the circuit supplying the fuse is much greater than that of the motor.
Test 1: stout wire to motor side of fuseholder from battery. Motor should run.
Test 2: same stout wire to other side of fuseholder
Test 3 : next connection back, etc.

 

[optimusprime]

Can anyone clear this up ,,and say if 2 types of motors were used . All i can find is the one with double squirel cage .

 

[d w124]

Can anyone clear this up ,,and say if 2 types of motors were used . All i can find is the one with double squirel cage .

Cars without aircon had a single,just like the one on the picture ^

 

[optimusprime]

Got it thank you ..

 

[sraouf]

Thanks for the link. I have a completely different blower motor however (see photo) and the resistor isn't located in this compartment.

I have a feeling that this might be it (2nd photo) and it's located behind the fuse box up under the windscreen... Bad news is that I have no idea how to remove it as I can't see any fixings and it's hardly easy to access!

Would appreciate any suggestions - resistor, heater control, and have even read about a link to a switch in the ignition barrel?

Thanks

Sorry to resurrect an old thread, but did you find out if the resistor was indeed the thing behind the fuse box? if so how did you remove it? mine looks the same and Im trying to figure out why the blower keeps blowing fuses. The motor itself looks/feels fine