Mod that keeps the cooling fans on when the AC is on ***Split***

[SBL]

I can't find the documentation on the mod that keeps the cooling fans on when the AC is on, regardless of the compressor being on, or where the mode with set to. It is somewhere out there.....

[Ron]

That is the way it is already wired from the factory. Sounds like the Cooling Fan Breaker might be tripping (40Amp. Maybe it's weak, high fan amp draw, ??)

[SBL]

Ron,

I am not so sure about this. I found the post by Darryl from the old list. Perhaps the early models did not have this feature and it was corrected later.

Here is the post:

Author/source: Darryl Tinnerstedt/McElraft

To prevent the cooling fans from cycling with the A/C compressor (i.e. they are on any time the A/C is on, regardless of the compressor cycle) do the following modification.

Locate the tubular diodes in the large wiring loom just inboard of the fuse box. Locate the pink wire and disconnect it from the diode. On a length of 16 gauge wire install an appropriate blade connector and plug it into the diode where the pink wire was. Route this wire under the console by tucking it under the console and pulling up on both ends. The other end of the wire should be up on the floor hump under the dashboard on the passenger side near where the wires from the A/C mode switch go to the pressure switch on the A/C accumulator behind the right front tire. Disconnect the pressure switch plug, and with the ignition switch ON and the mode switch in A/C use a test light to find the pink/orange wire leading to the pressure switch that is "Hot". Turn off the ignition and using a parallel wire splice (3M Scotchlok) connect the new wire to this hot lead. Reconnect the pressure switch and test the system.

The cooling fans should now run any time the mode switch is in A/C, regardless of whether the compressor is cycling on and off or not.

Original by Darryl Tinnerstedt/McElraft




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[David T]

That is the way it is already wired from the factory. Sounds like the Cooling Fan Breaker might be tripping (40Amp. Maybe it's weak, high fan amp draw, ??)

Make sure what is clicking, the relay or the cooling fan circuit breaker. The breaker usually won't click that fast. Check that you have the uprated (40A) circuit breaker. The relay should be clicking but 3-4 seconds is too fast and means you need some refrigerant or the low pressure switch needs to be adjusted.

[SBL]

David,

I don't really have a problem with cycling or clicking. I was just perturbed that when it does cycle, the cooling fans at the radiator go off. I remembered that there was a modification for this. But Ron says it is wired that way from the factory. So, I and trying to sort that out.

[Ron]

Ron,

I am not so sure about this...

I'm so sorry Steve!!! I missed where you said, "regardless of the compressor being on," somehow.

I assume the mod you found works. Hope this helps you follow it and/or make it easier to do:
PS-Bypass.jpg

[SBL]

Thanks Ron.

So, from the factory the radiator cooling fans will cycle with the compressor, correct?

I have not done the mod yet. I was thinking that an easier way to do this was to key the radiator fan relay with the +12 from the high setting of the AC fan (I always have it on the highest setting). Gee, that connection is right there a few inches away! Just a thought.

[Ron]

Yes, as long as the Otterstat doesn't override and turn them on...

If you mean as in the below, I think it would do as you say, but it would also make the fans run when the Heater was on and at 4th speed.
The diodes (circled) should prevent interference with other circuits.
(Maybe add a "summer/winter" switch in series with the jumper ;-)

PS-Bypass2.jpg

There is always a "but", eh?

[David T]

The stock (original) mode of operations of the fans is;
1) the "O" switch controls the fans on and off when the ignition is on
2) When the A/C compressor clutch engages the A/C overrides the "O" switch and causes the fans to run regardless of what the "O" switch wants.

The way the electrical system is set up the fans and the A/C MUST cycle. If you set up the A/C or the fans to run continuously you will overload the electrical system.

[Ron]

+1 on a stock system.

$.02:
3) When the "O" switch engages, it overrides the A/C and causes the fans to run, regardless of what the A/C switch wants.

$.04:
A D with one of the "high amp" (90+) aftermarket alternators (and the correct size pulley...) would keep up with the fans always on, and then some.

$64.00?:
What's an "O" switch? It sounds like something that 'Oughta be jumpered' for the hot summer months!!