cooling 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=11165
Printed Date: June 07, 2025 at 8:13 AM

Topic: cooling fan relay

Posted By: mwmcqu0
Subject: cooling fan relay
Date Posted: March 20, 2003 at 6:10 AM

I have a 90 camaro rs 305, and it started running hot two days ago, but only in city driving, not on the highway. I got home and checked the fan - it isn't coming on. I replaced the motor and the temp. sending unit for the fan, but that hasn't worked. The fuse is fine, so now I figure it's the cooling fan relay. But I've never worked with relays before; I don't even know what they look like or where they might be. I'm kinda stuck here, so any help would GREATLY be appreciated. Thanks a bunch.

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Mark
humbled grad student

Replies:

Posted By: cpgoose
Date Posted: March 20, 2003 at 6:29 AM

Hey...relays look like this:
https://www.bulldogsecurity.com/images/Model757.jpg

Your fan relay will look similar, and will have wires going to it. I had the same problem with my car. (I have a radiator fan AND a cooling fan). The fans are both up front by the radiator, and the relays were just to the side of the fans (kind of behind the headlights). My problem wasn't the relays, though. It actually was something called the "radiator fan timer" (I think). It was this little black box located under the dash behind the radio. When I touched it the fans came on, touched it again and they went off. So I knew the unit was bad. I replaced the unit ($130), and all was good again.

Posted By: benjammin1414
Date Posted: March 21, 2003 at 9:54 AM

I’m no mechanic but I do know twelve volts, the chance of that relay for the fan going out is slim but possible. But your problem sounds more like the thermostat. Have he checked that?

Posted By: mwmcqu0
Date Posted: March 21, 2003 at 11:09 AM

Hey thanks guys - I found the realy and replaced it too. But I figure it can't be the thermostat b/c the radiator fluid is circulating through the system like it should be; the only problem is the radiator fan. I ran out of time due to weather yesterday, but I'm gonna test it today. If it still doesn't work, I figure it must be the computer somehow (ugh...). Anyway, thanks alot for the replies. This site is pretty cool.

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Mark
humbled grad student

Posted By: cpgoose
Date Posted: March 21, 2003 at 11:22 AM

One other thing you could try to is to unplug your radiator fan (you should be able to find the plug easily) and (assuming it's got 2 terminals), put one terminal to ground and one to 12v+, and see if the fan turns on. It should turn on and run smoothly. It's a good way to rule out the fan and that wiring. good luck posted_image