Electrical guru's-help wiring up 2 fans into 1.

[turbovanman²]

Ok, I am moving my condensor in front of the rad and my van has 2 fans, one for the coolant and one for the a/c. They both work indepantly of each other so this is my plan. I have a stronger thinner fan that will be doing double duty. I have some 40 amp diodes that are getting installed on the power wires so when there both turned on, theres no back feeding of voltage. Now, don't laugh but if both are commanded on, will I get more than 12 volts or amperage being sent to the fan and will it melt anything?

[Stevien1]

I don't know why you would need to add diodes, just use the old radiator fan wires to connect to the new fan. Tie the a/c clutch relay to the radiator fan relay so when the compressor kicks on, so does the fan relay (along with the new fan). That way, your not messing around with the low amp control side instead.

-Chuck James

[turbovanman²]

I don't know why you would need to add diodes, just use the old radiator fan wires to connect to the new fan. Tie the a/c clutch relay to the radiator fan relay so when the compressor kicks on, so does the fan relay (along with the new fan). That way, your not messing around with the low amp control side instead.

-Chuck James

Ok, another idea, I was toying around with relays but your idea confuses me a bit. There is one control terminal on the relay so how would you run 2 control wires on one relay? tie them together and run diodes in them again so no backfeed?

[Turbulence]

what I ended up doing on mine was running the rad fan on all the time during the summer months--provided ground at the relay. Worked ok. I tried messing with the two relays. I couldn't get it to work. Fan would run constant and stop when the compressor kicked in. I gave up.

Hope you have better luck

Martin
90 Voyager TII
89 Horizon

[turbovanman²]

Thats why I am using the diodes, no back wash so to speak,

[4cefedomni]

hey Simon go to KMS carparts by ikea they have relay sockets for dual relays that are already wired together so that they will both go on by either signal wire.

[Frank]

what I ended up doing on mine was running the rad fan on all the time during the summer months--provided ground at the relay. Worked ok. I tried messing with the two relays. I couldn't get it to work. Fan would run constant and stop when the compressor kicked in. I gave up.

Hope you have better luck

Martin
90 Voyager TII
89 Horizon

That is because you had a normally closed relay. Then when it powered on, it opened and you no longer had power. You need a normally open relay.

[Frank]

Ok, I am moving my condensor in front of the rad and my van has 2 fans, one for the coolant and one for the a/c. They both work indepantly of each other so this is my plan. I have a stronger thinner fan that will be doing double duty. I have some 40 amp diodes that are getting installed on the power wires so when there both turned on, theres no back feeding of voltage. Now, don't laugh but if both are commanded on, will I get more than 12 volts or amperage being sent to the fan and will it melt anything?

Diodes dont work that way, nor does voltage. Hook the fan up normally with both leads from both fans. No matter how many 12volt lines you add, the potential difference is still the same. Since the fan is not current limited, adding the additional wires does not harm it.


Frank

[mech1nxh]

Simon
had a thought on your fan hook up....
if you could find an aftermarket (or a good j/y) 3 brush fan,
you could wire the a/c fan lead to the low brush and the cooling
fan lead to the high brush, looking at the wiring diag I think it would let
you retain all factory fan controls,

also Frank ...correct me if I'm thinking wrong here but with a three brush
fan and power commanded on to both + brushes .. isnt this technically
a parallel total resistance??? if so a three brush fan would need no fuse /
relay/ current/ wiring mods, plug and play maybee......with low and high speeds

[JDAWG]

Simon
had a thought on your fan hook up....
if you could find an aftermarket (or a good j/y) 3 brush fan,
you could wire the a/c fan lead to the low brush and the cooling
fan lead to the high brush, looking at the wiring diag I think it would let
you retain all factory fan controls,

also Frank ...correct me if I'm thinking wrong here but with a three brush
fan and power commanded on to both + brushes .. isnt this technically
a parallel total resistance??? if so a three brush fan would need no fuse /
relay/ current/ wiring mods, plug and play maybee......with low and high speeds

thats what i was thinking, alot of fans have a high and low setting, high for when the a/c is on. Ford Taurus's have this fan setup from the factory, maybe play with one of those first, then move to a good aftermarket

[turbovanman²]

Diodes dont work that way, nor does voltage. Hook the fan up normally with both leads from both fans. No matter how many 12volt lines you add, the potential difference is still the same. Since the fan is not current limited, adding the additional wires does not harm it.


Frank

Thats what I hoped. I am going to use the diodes though, the voltage could still backfeed, learned this when using the ALT power wire on GM's to power the HEI distributor, you would turn off the car and it would keep running, Install a diode, no more issues.

All good ideas, I am installing a much larger, stronger aftermarket fan and will try my way first-its the easiest. IF that fails, I will try the others.

[David Bohrer]

+1 on the diodes!

I just found my gremlin and it was the backfeed because of my wiring up two relays off of one ground/driver. Install diode and now the relays don't freak out!

[turbovanman²]

+1 on the diodes!

I just found my gremlin and it was the backfeed because of my wiring up two relays off of one ground/driver. Install diode and now the relays don't freak out!

Is that because of what I said or you found out from another source?


Have the fan in, covers almost the whole rad, almost finished the wiring. I shouldn't have any problems with overheating,

[turbovanman²]

Thought I would post an update. Well, it worked. I put a 30 amp diode in each fan power line, spliced it into my new 16 inch fan and it works perfectly. I turn on the coolant fan, then turn on the a/c relay and works. As a note, when turning on both relays, the fan does spin a little faster, you can hear it speed up.

[David Bohrer]

Both actually. You just triggered a good diag I had forgot to do!