Radiator Fans Don't seem like they want to kick on

[Alibi]

Hi all. This is on the '88 LeSabre.

I was replacing my thermostat a couple days ago (it seriously looked like the original at 165k miles) and I noticed that my cooling fans never kicked on after I turned the car back on to top off the fluid. I also ran it around town for a few minute and they still wouldn't kick on. They will turn on when I put the car in diagnostic mode (jumping the OBD port).

Is this a bad coolant temp sensor (CTS)? as the gauge on my cluster is either at 100* or maxed out at 280* and never in between (but that should be controlled by a separate sensor anyway).

Once I get a hold of a camera I'll take some pics of the thermostat, the housing (it broke trying to get it off) and the horribly rotted O ring just for reference...

[Alibi]

I've been working on the car this weekend and got lots of parts swapped out.

1. New 180* thermostat.
2. New thermostat housing and gasket (old one was so rotted it broke when I tried to remove).
3. New coolant temperature sensor (old one was covered in goo when I removed it).
4. New coolant temp switch (for the gauge).
5. New wiring that replaced some burnt-up wires.

I topped off the radiator and ran it around town. At first, my temp gage wouldn't work and it went straight up to 280* degrees on startup like it had been for the last few weeks. BUT... after I started driving it the gage started working again and it hovered around 100* for a while. It eventually climbed up some as I drove it around but the fans still didn't kick on.

So... then I went home, popped the hood and revved the motor in park. The primary fan finally kicked in so I guess the motor just hadn't had a chance to get to operating temps yet as its a cool night out right now.

I've got Heavy Duty Cooling so I've got dual fans. Only the main fan kicked on but the secondary, smaller fan did not. Does the second fan only kick on at higher temps or do I need to look for some bad wiring or something?

[crzydmnd72]

FWIW, I had an 88 Royale with HD cooling, smaller fan usually only turned on with AC on. Even after a long highway drive, if AC wasnt on, the second fan wasnt either.

Neither of my Bonneville's have HD cooling so I cant compare there.

And earlier when beating on my brothers Lesabre, I didnt notice if both fans were on then either, seems they werent at first but then he turned on AC and I heard fan noise, but was looking for leaks and totally didnt notice.

[Jrs3800]

Generally these fans will not come on till roughly 210F( Low Speed ) and 220-227F( High Speed )

When you put the car into diagnostic mode the ECM flips the fan relay on... Might put a scan tool on the car and see what the ECM thinks the engine temperature is..

[Alibi]

A scan tool is one of the few tools I don't have. Do you have any recommendations for a good one for an LN3?

Anyway, at the very least the main fan is kicking on so that is good. My AC system is gone so I cant test the second fan that way, but I can test it when jumping for codes. I'll do that and see if the second fan kicks on so that I at least know if it works or not.

Edit: So my brother got home and I took some pictures of all the parts I've replaced.

Coolant temperature sensor (CTS) and Coolant temperature switch (for cluster gage). Note the nasty gunk:



Broken T-stat housing and T-stat:





And this is supposedly a gasket... looks a little dry-rotted to me....