hi low/ fan relay

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=132141
Printed Date: May 16, 2025 at 12:46 PM

Topic: hi low/ fan relay

Posted By: jtm311
Subject: hi low/ fan relay
Date Posted: September 05, 2012 at 3:14 PM

Hello all,

I want to make a high/low relay setup for my car. does anyone see any problems with this design?

posted_image

Thank you

John

Replies:

Posted By: i am an idiot
Date Posted: September 05, 2012 at 3:42 PM

Are the 2 wires coming from the fan both positive wires? One low speed, and the other for high speed?

Posted By: jtm311
Date Posted: September 05, 2012 at 4:16 PM

yes one needs a 70 amp for high and one needs a 40 amp for low that is start up only of course.

Posted By: i am an idiot
Date Posted: September 05, 2012 at 8:11 PM

I see no problems with your diagram.

Posted By: oldspark
Date Posted: September 06, 2012 at 2:39 AM

I'd rather use 2 SPST relays, and hence also have redundancy.

If the top relay fails, you have no fan.

Posted By: jtm311
Date Posted: September 08, 2012 at 6:09 AM

Thank you I like the idea of added another realy.

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