Electric Fan Conversion with Aux AC Fan

[hamann318is]

I've searched around here and M42Club but haven't found an exact answer. For those of you that are running AC and the Electric Fan conversion, did you keep the stock Aux/Condenser fan?

I have the M44 fan set-up running the stock plug/wiring and am looking to do the R134 conversion. Right now, the radiator fan comes on when the AC button is pressed, which is what I'd expect, using the stock aux fan wiring. The stock aux fan is not plugged in.

However, are there any issues using this fan and AC? Would I need to run two fans, or can I get away with just the M44 fan?

Thanks for the help.

[roguetoaster]

From what others have said, you can safely ditch the second fan as you won't improve efficiency having one fan blow almost directly in to another.

The M44 is a two speed fan, right?

[hamann318is]

Awesome - that's what I was hoping. The M44 fan is two speed, and I have installed the lower temperature switch from the M44 (80/88). Right now the operation is no fan until about 3/5ths up the temp gauge, and then the fan kicks on until the temp reads around the normal hair under 1/2. The fan will also kick on with the AC snowflake on.

I'm not sure I've had a scenario that the high speed comes on, unless I just can't tell the difference between the two speeds.

[CanadianDirty30]

I'm not sure I've had a scenario that the high speed comes on, unless I just can't tell the difference between the two speeds.

Pretty sure you'd know if the second speed kicked in, sounds like an airplane on mine lol. It should only really come on if the temp goes way above half.

[slowmoe30]

If you want to hear what each fan speed sounds like, go to the temp switch by the radiator and short each trigger circuit while the car electronics are on.

The stock M42 switch was wired so that:
- GRN/BLK to BK/BRN triggers the Low Temp relay to power the fan
- GRN/BLK to BK triggers the High Temp relay to power the fan

So, to trigger the desired fan mode, short the appropriate two pins.

The M42 Aux fan pigtail has three wires:
- Low Temp power (Black)
- High Temp power (Red)
- Ground (Brown)

Following the harness to the fan, the black wire supplies power just like the red, except there is a box in the way. I assume this is a resistor so the power coming from black is split between driving the fan and the resistor, ie. less power to the fan, and less fan noise.

So for mine I started with a 16" SPAL fan which only has one power cable.
I cut the pigtail off the old aux fan (which was dead), and soldered the SPAL power cable to both red and black on the old pigtail. This allowed me to use the stock fan connector on the chassis harness (the SPAL connector wasnt waterproof).
This means the SPAL comes on full strength when either the low or high temp is triggered (as it should be, given that the switches are exclusive to each other, ie. when HT turns on, LT turns off).
Now, for noise reasons, I could have kept the old resistor in series with the black wire so the SPAL only gets some power at LT trigger, but the resistor on the old aux fan was dead.