re heater/blower fan 635 csi

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mikex1
Posts: 6
Joined: Tue Jul 15, 2014 1:19 pm
Location: barossa valley

re heater/blower fan 635 csi

Post by mikex1 »

Hi, my heater/blower fan only works on full speed,you cannot regulate the fan speed with variable fan switch . When you turn on air conditioner with blue button,the variable fan switch works,the fan will vary in speed. I know the air conditioner fan is in under front console area,heater/blower fan is on firewall under bonnet. I have replaced the heater /blower fan with new electric motor because noisy at speed and vibrated,probably bearings and replaced tumbler blades on electric motor with original ones. The fan works well now,not noisy as used to be, but cannot vary speed,full blast or nothing. I researched this and appears there is resistor under the housing of heater/blower fan on firewall,is this resistor creating issue with variable speed of fan, what your thoughts on this matter. thanking members mikex1
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635sharknose
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Re: re heater/blower fan 635 csi

Post by 635sharknose »

The transistor of the heater fan is most likely broken. The transistor on the air conditioner fan is still OK, that's why it does work with air conditioner on and doesn't with the air conditioner off.

I replaced mine by this part, works perfectly: Darlington MJ11028
Can be bought on Ebay for a few $.

The transistor is located just behind the fan motor under the hood.
Do not forget to add cooling paste when you mount the new transistor otherwise it will be broken in no time.

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Paul
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1987 635CSi Bronzitbeige
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