87 Gn Radiator Fan Help!

[87GNTTOP]

My fan was working fine and then it just quit. If I run a hotwire to the fan, the fan will kick on and run fine.

I have checked all the fuses and they are all good. Can anyone tell me where to start to look.


Note: I did not have the typical problem of the fan staying on after I shut the car off, killing the battery. I know about that bigger relay. Not that.

 

[ChavoLC2]

Fan Relays

It's probably the hi and low fan relays on the drivers side inner fenderwell. They are actually the same relaysThey cost around 11 bucks each. when mine went out I just changed both relays.

 

[87GNTTOP]

Is there any way to identify which relay is bad? Or identify if this is the problem at all? Thanks

 

[ChavoLC2]

You could swap em

If you've already jumped them with a hotwire and the fan worked then I would think they're toast. The ECM controls the fan there is no fuses to the fan. You could switch em out with each other and see if the fan comes on at above 160. If it does then it the low fan relay that out. Think that if the lo relay was working the fan would come on at a tad above 160 degrees(it you have a 160 stat.)so for sure the lo relay is out if the fan ain't coming on, believe the high relay comes on when engine temp is over 210 or some temp like that. Guess you'd have to run your car to above the limit for the ECM to activate high relay to kick fan on. Man I just bought 2 relays slapped em in and the fan worked at both levels.

Man it's the cost of buying the family dinner at a Fast Food joint. Actually bought 2 extra relays(11 bucks each) from Gyrhead just to have, because when I needed them I had to call around town, then run to one NAPA then to Checkers on the other side of town, most places don't have them and if they do they have one. So I keep a couple of em as spares. Gyrhead has alot of sensors and relays for a reasonable price and they are usually AC Delco then some Autozone off brand.

 

[87GNTTOP]

Well here is the update. I went to Advance auto parts and purchased 2 new fan relays and replaced them both. $7.77 each, how can you go wrong at that price.

Anyways, still nothing?? Any suggestions, what are the chances that the sender went bad?

 

[87GNTTOP]

Still need help. TTT

 

[texasturbo]

The temp sensor on mine went bad. It is located on the Intake manifold. It has the one Green/yellow wire gong to it... It may show open with a VOM...

 

[87GNTTOP]

The temp sensor on mine went bad. It is located on the Intake manifold. It has the one Green/yellow wire gong to it... It may show open with a VOM...

Roughly, how much is the temp sender? I was going to try that next.

Thanks

 

[bmackinnon]

If you've already jumped them with a hotwire and the fan worked then I would think they're toast. The ECM controls the fan there is no fuses to the fan. You could switch em out with each other and see if the fan comes on at above 160. If it does then it the low fan relay that out. Think that if the lo relay was working the fan would come on at a tad above 160 degrees(it you have a 160 stat.)so for sure the lo relay is out if the fan ain't coming on, believe the high relay comes on when engine temp is over 210 or some temp like that. Guess you'd have to run your car to above the limit for the ECM to activate high relay to kick fan on..

Wrong.... YES, there is a fuse... it's the A/C/Fan fuse under the dash (I think that's the label/name of it, I'll go check in a bit). I fought my 'no-fan' situation FOREVER, using the factory service manual/troubleshooting trees. Jumping relays, probing for continuity, grounds, etc, etc, etc.... I (somehow/finally) found 3 different diagnostic charts in 3 completely different sections of the manual, all 3 being similar in both procedure and intent, but slightly different in method. Only one of the sections said to check that fuse (of course, the last one I followed), and guess what.... after years of intermittently trying to diagnose/fix, and giving up and using a hotwire/switch, that damn fuse was blown. Replaced it and fan works perfectly. And yes, I felt like a complete ASS!!!


Double/triple check that fuse, and get back to us. If that's not the problem, I'm sure I can help you figure it out.... I believe I deserve a doctorate degree in turbobuick fan control systems after all the 'research' I've done....

There's some other misinformation above, but check the fuse again first, please...

 

[bmackinnon]

I went and checked, and the fuse is labelled simply "A/C" - 25 amps, located 3 rows directly above the 30A brake (powermonster) fuse. (mid-upper right of fuse block). Gotta' have it for either speed fan to come on automatically. I re-read your post, and if the fan was fine, and 'just quit', and you've replaced both relays, I'll make a small wager that fuse blew. BTW, if you've got any type of scan tool, if the coolant temp field reads correctly, the temp sender is not the prob.

Let us know.... I'm subscribed..

 

[mazdatech78]

I had a problem once with my fan. It just stopped working. Turned out to be a bad ground. Repaired the ground and the fan has been working fine ever since.
Double check the grounds on the back of your heads.

James

 

[scottyb]

The switch on top of the intake is for high speed (temp > ~210, not exactly sure, but more than 200). You can remove the connector to this and ground it to activate high relay - help rule out the relay. Low speed is controlled by the ECM/chip settings, usually ~170 on most chips.

 

[87GNTTOP]

Well I finally got it. The culprit was the sender on top of the intake manifold as someone suggested. Put a new one in and works like a charm. So now I have a new sender and two new relays. I will keep the old relays as spares.

Thanks for all the help!!