Low/high speed fan question.

[DAKOTAKIDD]

I know my car (91eco diesel jetta) has an automatic fan cut in and supposibly a 2 speed fan.  I have never heard the fan pick up speed.  Any way, before I test the system,  does the air conditioning have to be operational for the auto/2 speed fan to work normally?

Thx

[Baron VonZeppelin]

I asked similar question on Vortex a while back, about what makes fan go to the high speed.

From what i gathered by replies (and not absolutely 100% certain) Yes, your a/c would need to be in operation (selected on dash control) for it to call on the high speed.

As you probly know, it runs at low speed on a regular cycle as needed.
Also, it runs at low speed constantly anytime the a/c dash control is on an a/c compressor acquainted selection.
So when temp climbs - while an a/c acquainted selection is in use - it calls the high speed into operation.

Mind you, the a/c would not have to be "fully operational" as in charged up and blowing cold, for the fan to operate in this manner. Just everything electrical would need to be in order. And proper selection made on dash control.

It's easy to test both speeds of the fan at the main plug using two jumper wires. From memory the center terminal is ground, and the outer terminals are 1 for slow, and 1 for fast. The colors of wire going to them will correct me if i'm wrong.

[8v-of-fury]

Quick Hijack here, is it only A/c equipped cars that came with dual speed fans?

I have a mk1 jetta, and she gets to about just past the 3/4 mark before the fan kicks on and cools her down to 1/4.. I would much rather manually be able to switch the fan on.. you know? and have it be able to be high speed too! what do ya'll think?

[Baron VonZeppelin]

8v, you'd have to check your fan plug and see if it has 2 or 3 wires.
3 wires is 2 speed fan.
I'm not sure which your car will have.
But you can probably swap a 2 speeder onto it if it doesn't have one.

And then wire it anyway you want it to work, for sure.

I ran my 89 NA for 16 months without the fan being functional at all.
Just because the gauge always stayed 1/4 to 1/3 when driving.
(one of those just do it later deals)
It had to sit idling for extended time to get close to half.
I fixed the fan (was justa bad contact) but it rarely if ever comes on that i'm aware of while driving. I don't use the a/c - maybe next year.

All cars are different.
And we have different type cars on top of that.
But it would take me a while to get used to seeing 3/4 on the temp gauge.
Just the visual effect. Maybe yours is just "saying" it gets that hot.
I get wiggy when they go past 1/2 unless its a Tbo Dzl getting nailed.

[8v-of-fury]

Well the only reason I ask is because until the fan comes on in my 1.7 it gets to the 3/4 and almost 7/8 mark 

Kinda freaks you out when you get that high.. plus you can feel that the car is hella-hot before the fan comes on too.. so i was thinking of maybe adding a switch.. and im pretty sure stock fan now has only two wires.. so one speed, but still when the fan kicks on you can see the temp drop immediately.. and fast.

So i guess a switch it is for me, Do i just tie in to the fans power line? so that way it will still turn on when it needs and when i want it... or will power from either source try and get back through the opposing power wires and be bad?

I may even just have it completely manual.. No-one drives my car, and I love everything to be manual. Like when the fan comes on and you start moving, there is no need for it to be on right? I could probably save a few years on the fan with killing it off when it is not needed on

[Baron VonZeppelin]

Wait a minute, you still don't have the 1.6 swap done on that car ?
Or do you have more than one mk1 Jetta ?
Been a while since you put anything about it on Vortex.
So i'm behind on its progress reports.

If you wanted to go full manual control - i would just unplug factory plug and tape it over to keep it clean inside - and pull the fuse from fuse panel. And make all new wires and a switch.

It might could just be your rad thermal switch is getting old and lazy.
I'm with you and wouldn't want to go with Always On either - unless it just really needed it to be that way.

[jtanguay]

watchout if you directly wire the fan.  if you wire it for high speed only, you can burn the fan out in about 5-10 minutes of constant use. (ask he how i know  ) i recommend using the low speed, as it can be run indefinitely provided the motor is in decent shape.

cars with a/c have an extra low speed provided by a resistor mounted on the shroud. it is always energized when a/c is on. a/c can kick on the fans high speed mode when the refrigerant goes above a certain temp (not quite sure what that is) and i'm pretty sure that the a/c can be cut off if the coolant temp becomes too hot as well.  it's a pretty well designed system, but if the resistor blows, the whole system is in jeopardy (head gasket failure is usually the result if the driver does not pay attention to engine temp).

[Quantum TD]

ECO fan wiring explained:

http://www.vwdiesel.net/forum/index.php?topic=20393.0