[VTSTS]

Hello again, maybe some of you saw my older post about my overheating problem. Well not overheating for say I guess. I've been driving the car since a drain/refill of coolant, new coolant temp sensor, new fan relays, and new drivers side cooling fan. Motor was gone. I can drive the car (97 sts) all day long, work and back 40 mile trip 1 way, or drive it 200 mile trips. Doesn't overheat, this is highway driving. The temp stays at 203-208, will go up to 208, then back down eventually to 203 ect, ect.
BUT
When I get into city driving, stop n go, or a lot of idling, the car will get to 226, then 235, and I wont let it get by 240. I look at it in the garage here and the fans just don't kick on. I got them on a switch so I can make it in city driving. Ill kick them on at 226, then it gets back to 208.
Now no signs like I said of hg failure in the old post. I was wondering what your thoughts are. Changed the oil, no coolant in it. Drained coolant and replaced, no oil in there.
This car runs great, I just want it fixed, you know. I do most all my work myself, just not good at diognosis. Thanks and all help is much appreciated.
Mike

 

[Submariner409]

Something's still not right - the fans should automatically go to slow at 224 degrees or any time an A/C function is commanded, and to fast at about 236.

The fan control circuit just isn't getting the right temp signals.

 

[Ranger]

Check the condenser fins. Might even try flushing it out with a garden hose. Clean out the dirt & dead bugs.

 

[VTSTS]

Could it possibly be because I have no a/c function due to very low refridgerant? When I hit the a/c button, the a/c comes on for 5 seconds, then shuts off, says a/c comp. off, very low refridgenant. The fan will come on for a split second, then blow the 50 maxi fuse?

 

[Submariner409]

Which fan blows a 50 amp (!!!) Maxi fuse ?? The cooling fans have 30A fuses, the A/C clutch has a 15A fuse to a healthy relay, and the ABS and A.I.R. pumps are the only 50A fuses in the front box.

You really need a GM Factory Service Manual with all the wiring diagrams for your particular car; Haynes and Chilton's won't do the job...........

 

[VTSTS]

In the motor fuse panel, where the maxi fuses are, bottom right has a 50A also on my diagram in my manual states that this 50 maxi fuse is cooling fans.

 

[Submariner409]

That 50A puppy must run the whole thing - later, when 'they' went to the relays in the engine compartment fuse box, the fan fuses (2) must have dropped to 30A.

You'll have to admit that it takes one heck of a lot of draw to pop a 50A fuse........

I'm out of ideas.....do your fan blades spin freely when flicked with a finger ?? Something's still fishy.......a bad ground or a fan wired backwards....

 

[Mark C]

The 50 amp fuse feeds power to the fans thru the contacts of two relays wired in parallel on a 97. Not really sure if these are 2 of the 3 relays down between the fans, or another 2 relays (I didn't follow the wiring diagram past the fuse block page) upstream of those 3.

Obviously its an air flow issue since it overheats at idle but not on the highway. One, or both of you fans are shorted somewhere. The fan wiring harness does run along the front edge of the engine cradle and passes very near the front exhaust manifold so it could be damaged somewhere and shorting out there as well.

 

[VTSTS]

Yes, it is the 3 relay system. They are down between the 2 fans. I have also replaced these as a good measure. Just about free so I just did it.
Now you say air flow issue. Where is this occuring? Or the numerous places this could occur?
The harness the fans/relays run into does sit near the mani, and basically sitting in a very hot places. All the way back too.
So I guess where I am at is taking the haness cover/s off, and looking for a bad wire. Broke, melted, ect? Thanks all for the great advice, I hoped it wasn't going to come to wiring, but here I am. I'll let you know the results. Mike

 

[VTSTS]

That 50A puppy must run the whole thing - later, when 'they' went to the relays in the engine compartment fuse box, the fan fuses (2) must have dropped to 30A.

You'll have to admit that it takes one heck of a lot of draw to pop a 50A fuse........

I'm out of ideas.....do your fan blades spin freely when flicked with a finger ?? Something's still fishy.......a bad ground or a fan wired backwards....

1 Fan fuse.


They spin freely, brand new one on drivers side, and passenger side turns on with my switch. BUT even when I run a switch on just the drivers side, when I flick the switch it turns on the passenger side fan instead. Cannot get drivers side to work at all. Weird

 

[Krashed989]

So I guess where I am at is taking the haness cover/s off, and looking for a bad wire. Broke, melted, ect?

Nope... You only do that after you've found which wire the problem lies in and you know the connectors aren't the problem. Nobody want's to take off the harness cover and most times you don't have to. All you need is a test light, an ohmmeter and a good wiring diagram.

The relays work like this:

Relay #1 = fan enable relay

When relay #1 is actvated, it runs a series circuit which powers both fans at low speed. The circuit also goes through the not activated relay #2.

When relay #1, #2, and #3 are all activated they power a parallel circuit to both fans for high speed. Relays #1 and #2 power the divers side fan and relay #3 powers the passenger side fan.

The relays are numbered going from drivers side to passenger side.