blower and aux.fan connected?

About a week ago, the heater blower fan quit working. dont know why.
Then noticed the engine starting to overheat while in traffic and realized that the aux. electric fan doesnt kick on. is this a coincedence or are they connected somehow. Im getting cold and the jeep is getting too hot!!!!
the fuse for the blower is fine. Cant figure it out. Its a 89 4.0. could it be a temp.sensor or something??? Any ideas?

the wires for the fan in my 87 ar loose in the heater control unit. I have to smack the top of the dash on really cold days, I just call it percussive maintenance.
I can't help you with the cooling fan, I only have the mechanical fan. It seems to me like the mechanical fan should be enough to cool it alone, especially in colder weather.

still confused.trying to figure out wiring diagrams in haynes manual.
Now i have realized that the ac doesnt kick on either. The cruise control quit working about 2 months ago also. which sensor or relay might be affecting blower,ac and electric fan. Also the manual shows a fuse(red wire,link Q????).

89? That's RENIX...

The auxiliary cooling fan is a separate circuit, which is tripped by either the thermal fan switch (driver's side radiator tank) or the ECM (A/C REQ - Air Conditioning Request Signal.) It's possible to add a toggle in a convenient location, wired in parallel with the thermal fan switch, to create an "override" to turn the fan on - I've done it several times.

So, if the blower fan has quit, would the aux cooling fan? Not likely, unless it fails at the same time. They are separate circuits (even with the A/C REQ line - it's a branch anyhow) and there's no reason for the one to affect the other.

Things I'd check...
Aux Fan Fuze (not really sure where THAT is!)
Aux Fan Relay (driver's fenderwell, back about a foot from the front crossmember)
Thermal Fan Switch (I've had a few of these fail. Either use a pot of water and a candy thermometer, or just take a jumper and connect the two leads on the harness end. I've had so many TFS units fail that I've just made a jumper that plugs on to the harness...
Failing all that, it's time to jump +12V to the fan, and see if it runs. If it runs backwards, you've got the power hooked up the wrong way...

Most of these tests can be done with everything (or nearly everything) in place, and you should be able to get them all done inside of an hour.

5-90

Grounds maybe, time for a major cleaning and maybe wire replacement. Clean your battery terminals with baking soda and water.