want a radiator fan switch on inside

[thejman3]

hey guys,
i want to install a switch on the inside to turn my fan on before the motor heats up while sitting in traffic or a drive thru on those hot days. i think by knowing beforehand that i'll be sitting in the heat for a while and turning the fans on before it has a chance to get hot would be alot better for the motor.

now, i would still like the factory settings to stay (fan turns on at 222) but i would also like to override that with a switch when i want.

i'm thinking just piggy back the factory wires with taps and a switch? will this work?

[LMP]

No problem. THe fans are turned on by a relay. THe best would be to switch the relays rather than the high current to the fans themselves. This is done by grounding the low side of the relay coils. RUn 2 wires, one from each relay ground side, to the separate contacts of a 2 pole switch. The switch wiper contacts then will go to ground . Just in case, as you do not mention model year, here is the '93 diagram .
www.avigex.ca/xport/coolantfan.jpg

[thejman3]

thanks LMP, i forgot to add its a 96 so would it be the same?. also could you draw me a rough sketch for a general idea? i have a clue but just want to make sure. thanks!

[LMP]

I'd do it like this:

[thejman3]

thanks for the drawing, so all i need to do is tap the 2 ground leads from each relay and put them to my toggle switch, now you say run the 2 grounds from the relay's to a separate post, would it be bad to tie them together to a single post? reason i ask is i have a bunch of 3 post switches already that i could use.

and after that i just ground and put a hot lead on the switch just like installing aftermarket fog lights or something correct? then when i flip the switch the relay's get grounded and fan turns on.

now last question, will the fans run at the normal or fast speed with this setup? or does this van have a 2 speed fan?
thanks!

[LMP]

Originally Posted by thejman3

1 ... run the 2 grounds from the relay's to a separate post, would it be bad to tie them together to a single post?

2 i have a bunch of 3 post switches already that i could use.

3 after that i just ground and put a hot lead on the switch ... then when i flip the switch the relay's get grounded and fan turns on.

4 now last question, will the fans run at the normal or fast speed with this setup? or does this van have a 2 speed fan?
!

1,2,3,4 point to questions above
1 if they are tied together, this would make both fans run together even when the computer calls for only one (when your switch if off)
2 confusing here. Douple pole switch has AT LEAST 4 connectors, most often 6 connectors. post/send me a picture to be sure. Verify this link http://www.kpsec.freeuk.com/components/switch.htm your switch must be of the dual/double pole type (DPST or DPDT ) or then use 2 separate simple pole switches SPST or SPDT
3 when one says HOT lead in that contect, it means it carries 12V...that is a no no here. Keep the vocabulary thight...ground is all tha tis needed.
4 Fan circuits on mine are one speed only. THe diagram I posted is indicative of the principle. I know 97 and after have 2 speed fans, I do not know for '96

However, and before anything, turning the A/C on immediately starts both fans....if the conditions you consider would already let you use the a/c....you need doing nothing more!

[thejman3]

ok i understand now, i had the wrong switch in mind. i just need a switch that gets grounded then goes to the fan relay, no power (hot) wire needed at all. would this switch be correct?
http://img205.imageshack.us/img205/3783/swdpst.jpg
http://img263.imageshack.us/img263/5601/swdpst.gif

also where would the best place to tap into the relay grounds? where are they located in the engine bay?
thanks for your time and help

[LMP]

Aok
Locating the wiring is the problem. The relays are behind the right headlight in my '93
www.avigex.ca/xport/relays.jpg
NOtice the sequence might not be the same.

[thejman3]

hey LMP take a look at these and tell me if they will work
http://cgi.ebay.com/ROCKER-SWITCH-IL...item3358c3edd0

[LMP]

DPST: double pole, single throw. THe right stuff.