Auxillary fan not working

[renegade]

On my 1989 325i:

The auxillary fan (the one in front of the AC condenser) runs at high speed only when I turn on the AC switch on the center panel.

I have a new radiator and a new double-temperature switch (the one on the side of the radiator), all the fuses are intact, I've replaced the relay that controls the low-speed circuit of the fan, no luck so far.

I don't think the car's been hot enough so far to trigger the high speed circuit but with summer approaching, I'm afraid things might get out of hand...

Just wondering if anyone here has dealt with this before?

Thanks guys!
Kaushik

[DaN]

Has it gotten hot enough to engage the low speed operation? Does the car overheat?
Why you worried about it?

[renegade]

Just because I'm anal and I'm following the "goddamn thing should WORK" philosophy! :D

To answer your question, no the car is not overheating, but I *do* think it might have gotten hot enough a couple of times where I fellt the low-speed fan should have kicked in (about a quarter inch past the half-way mark on the temperature gauge). However, the egine fan was always enough to cool it back down...

So, to answer your other question, I really have no *good* reason to worry about it except, like I said, for the fact that when I jump the low speed circuit (at the plug that connects to the radiator switch), the fan doesn't run...

There *is* one other issue with this. The low speed circuit normally takes a 15amp fuse. If I put one in there, it blows out when the fan runs on high (for example when I run the AC). The only way to run the fan is to replace that fuse with a 30amp fuse, which is what I have in there now. This makes me think that the load-reduction relay might be bad (not sure about this though).

There, now aren't you sorry you asked? ;)

[Madhatter]

I didnt think it was a thermofan, i thought it's primary purpose was to be used for the AC only, not anything else. You still have the clutch fan right?

Replace the fuse with a slow blo item, fans have enormous current draw when starting

[DaN]

These use resistors don't they?
Seems like the low speed resistor is faulty allowing too much current draw. Check the resistance of it.

[Madhatter]

maybe you are thinking of the fan inside (ie the heater/ac one) and not the one at the front of the car. AFAIK it only works or doesnt work.

[DaN]

I know we are talking about the same fan in front of the radiator/condenser.
how can they regulate the speed of the fan? How is there a low and high speed without voltage reduction?
Whats this?