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ElmerFudd GenII
5/26/2007 17:58:36
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Subject: Electric Fan A/C Question IP: Logged
Message: Finally had a chance to put in my Electric Fan. Just need to hook up the wiring. I'm using the flex-a-lite adjustable temperature control and it says that if you want you can connect to the positive wire that triggers the A/C compressor.
Larry - it says it's optional. Should I do this or is it not necessary with A/C? I'm not sure what wire to tap or which one triggers the A/C compressor. I'm putting in a manual switch I guess I could just turn on the fan when the A/C's running.
Intalled the fan into the shroud, looks good, took forever to beat the nut off the old fan.
Thanks for the help.
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dakota49 Dodge Dakota JOIN HERE
5/26/2007 21:16:52
| RE: Electric Fan A/C Question IP: Logged
Message: I think the reason they offer hooking up to the A/C wire is because the A/C gets hot a lot faster than the water will and by cooling the A/C core it takes a little pressure off the A/C compressor. All big trucks (like Kenworth, Mack,ect.) have the fan come on when the A/C compressure gets high, then it cools down and will shut off, doesn't have anything to do with water temp. I think it would be a good idea to wire it with the A/C wire if it uses a relay. If not I would wire in a elay and still use the A/C wire.
That's just my idea though, I am sure Larry will have a better idea. I work on mostly big trucks and my own Dakota. Good Luck. I also drive big trucks for a living.
88 Dakota 4X4 3.9
Dakota49
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TexasTodd Dodge Dakota JOIN HERE
5/27/2007 05:22:02
| RE: Electric Fan A/C Question IP: Logged
Message: Just happened by.
The stock 4.7's electric fans come on at two different times.
1. When the a/c is engaged, even at start up.
2. when the trmp climbs to a preset point, w/o the a/c being on.
I, as well as others, have taken my beltdriven clutch fan off and just run my stock electric fan.
I did put a 180 degree T-stat in.
FWIW
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Luke Dodge Dakota JOIN HERE
5/27/2007 10:27:27
| RE: Electric Fan A/C Question IP: Logged
Message: I would for sure wire the fan to the compressor. The fan doesn't
take a LITTLE pressure off the compressor, it takes a LOT of
pressure off the compressor. Besides, your air conditioning will
not get cold when not moving without a fan pulling air through
the condensor. I wouldn't recommend running the switch
manually for the air conditioning. I speak from experience. In
the beginning I forgot to turn the switch on a couple of times
and the refrigerant got to such high pressure at idle that it
vented into the engine bay. Looks like smoke coming out and
sounds like a foghorn. Whenever the compressor is engaged,
the condensor has to have air running through it. Pressure's can
rise as high as 350-400 psi on the high side without airflow.
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ElmerFudd GenII
5/28/2007 21:13:50
| RE: Electric Fan A/C Question IP: Logged
Message: Thanks, sounds like I need to hook up the fan control to the A/C. The compressor has two wires one black with white stripe and one black. I figure one's constant 12v source the other's the one you tie into which completes the circuit when you turn on the A/C. Any idea which is which?
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J and J Auto GenII
5/29/2007 03:16:32
| RE: Electric Fan A/C Question IP: Logged
Message: If you look close you will see 2 wires going to
the electric clutch on the A/C unit
1 wire power all the time
2nd wire on off ground side
Does this flexolite control wire not go to the
ground side of this switch
This will turn the fan on when a/c compreser is on
If you do a lot of stop and go city yes otherwise
not needed
I like to set the thermos with a scanner and
engine temp sensor
mine is at 188 on off at 185 on the high way it
runs 183 185 only once in a while in slow town
traffic does it come on on 90 to 100 days it
comes on going slow under 30 35mph
Larry J&J Auto
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ElmerFudd GenII
5/29/2007 07:56:10
| RE: Electric Fan A/C Question IP: Logged
Message: I would think it goes to the negative lead other wise the fan would always be on. The instructions say connect the control module to the positive wire that triggers the A/C compressor. Use a voltmeter to determine which wire coming from the compressor is the positive trigger wire. I would think when the A/C switch is on the negative wire becomes the trigger wire as it completes the circuit. I'll have to figure it out when I finish hooking it up Saturday. Thanks.
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ElmerFudd GenII
6/04/2007 08:12:03
| RE: Electric Fan A/C Question IP: Logged
Message: Finished with the install. Tapped the AC line to the compressor and the fan comes on when the AC is turned on. Also put a relay switch in as a backup if the control module fails. Works well, next mod the computer which is back ordered. Won't have it until July.
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