So I finally got the time to fix the fuel pump, fired it up and ran it around the block and parked it and let it idle for 10 minutes. I looked at the temp and it was at 250 and climbing. The radiator fan hasn't kicked on. Any suggestions? The book says check the relays, fuses etc... I did have time to check the fuse and that is fine. I have a feeling that it is the thermostat but I don't know the best way to test it. Any help is appreciated.

 

it might just be the fan relay. pull it off, and just reinstall it. sometimes that's all it needs to just work is be reseated. If that doesn't work, you can put a new relay in. after all, it's 26 years old, and worked up till now. and it's $7.

 

I'm not all that knowledgeable with electrical. Is there a simple way to test the relay? Possibly use jumper wires to see if the fan turns on when the relay is bypassed? Or can I put battery voltage to the fan itself to trace the problem?

 

Also in reading some other posts I saw that the fan should come on when the A/C it turned on. I had the A/C on and the fan didn't come on at any temp. Does that isolate the problem any more? Could it be a fan sensor of some sort or does the computer turn on the fan thru the relay when the thermostat reaches a certain temperature?

 

The sensor in the pass. side head is for the fan, unplug it, run a jumper wire from ground to the sensor plug. With the key on the fan should run.Check for continuity between that plug & relay. W/ it still jumped to ground, you can check for 12v & ground at the fan plug.
Does the upper hose get hot? If yes, then the t-stat is opening.

 

Computer doesn't control fan in your year model; mech switches only
Since neither of the two independent switches turn the fan on it is pointing to a relay ( or fan itself) problem .Hotwire the fan up and confirm it actually works 1st.

Check you have 12V on the red power wire going into relay . Then bypass the relay by jumpering red to red/ black on the plug and fan should run .You should also have 12V on blue relay control wire when key is on

 

Thanks for the info I will keep you posted once I find the problem. Can I get the relay @ Napa or Advanced? Or should I get it from GM directly?

 

So I jumped the t-stat wire and nothing happened. I'm not 100% sure I was getting a good ground, so I moved to test the relay. I jumped the red and blk/red and nothing happened that way either. I then applied battery voltage directly to the blk/red in the relay harness and the fan turned on. Any ideas? The manual says when i jump the red and blk/red in the relay harness the fan should come on, which it didn't and I am fairly certain I had a good connection. I have now ruled out that the fan motor is bad. Could it be a bad ground somewhere since jumping the relay didn't work? I assume that there is a bad ground somewhere between the relay and the fan but I wouldn't know where to begin since the relay plug goes directly into a harness that is covered with the plastic shielding.
If I jump the relay and use a test light on the fan itself would that rule out a bad ground? If so, where do I go from there? I can re-check the t-stat to ground and see if the fan comes on but, my concern is that there may be more that one problem and I don't know how to isolate 2 issues at the same time. Is it worth taking out the t-stat on the right head and seeing if it is clogged or something or would that not factor into the issue since it appears to be electrical. I have already checked the fuse and the 3amp fuse was fine. Any help is greatly appreciated, and sorry for so many questions.

Thanks,
Solomon

 

So I just tested the blue wire with a test light and nothing. I also tried jumping it but of course nothing. I don't think that there is any power coming into the relay. If I apply 12V to the blk/red the fan turns on. So for some reason there isn't any power coming into the relay from one of the 3 other wires. The harness is as follows...
Terminal A - Black/Red
Terminal B - Green
Terminal C - Blue
Terminal D - Red
Terminal E - Empty

 

If no power on red then you may have blown the fusible link .
it is on the starter end of thick red wire coming off the starter to fan relay.
Try putting 12V temporarily on to the Terminal D ( Red ) at relay and see if anything works
(Turn A/c on to test or ground the wire at thermo switch )
Blue wire from fuse should be hot with the key on only

 

Ok, thanks I will check that. What am I looking for? The manual that I have doesn't mention that so I am not sure where to look.

 

So I found the link but there doesn't appear to be a way to test it. I read that I just have to replace it but it doesn't say what size I need to replace it with. Can I use a regular fused connector and just splice it in?

 

^^yes......just cut out any green or corroded wires and replace. Since all that is low on the motor and water gets it.....tape it all back up....wrap it all in electrical tape

 

What size fuse should it be? The stupid Haynes manual doesn't tell me anything about this.

 

How are you testing for power? Get a test light as it can test both for 12v & ground, depending on which post of the battery its hooked to.
Ok, heres how I do a quick test, get a 12v test light hooked to ground. With the key on you should see power at DK. Blue & Red wires at the relay. Also if you probe the Dk Green(Wt stripe), you should here the relay click & fan should turn on.

 

Nope no luck. I think that the fuseable link is bad, I bought a replacement fuse holder that I will splice in, I'm just not sure what size fuse to put in the fuse holder.

 

^^Wait, there is an actual "fuse"in there somewhere?

Most time a fusible link is a flat spot of metal that is weaker that the stranded wire connected to either side... the flat piece burns first when the wire gets hot.

When I had a "fusible link" burned.......there was a fusible link....it was just way up by the battery...my issue was a wire that had rotted out down by the starter.

When I found it, the wire basically would crumble when I rolled it between my fingers.

So just cut out the old wire and splice in new.

 

I don't know I guess I just assumed that it did. Napa didn't have and couldn't even look up an actual fuseable link, so I figured that a fuse holder would work.

Are you saying you just spliced in a piece of wire and that was it?