Neither of my Aux fans are running when it gets hot and after about 30-40 min of driving my temp gauge starts to rise.

My question: Is there a way to ensure that both motors are dead or is there a chance a relay or something could be bad?

Also, at what point should they kick in?

 

On my 97 D1, the fans both switch on as soon as the AC is turned on, no matter engine temp. I believe engine has to be quite warm and switched off for fans to continue to run. They are controlled by a relay, which you can find in the RAVE documents. If a lot of work was done, be sure no one reverse wired them like my PO, mine were blowing out the front of the vehicle. This time of year a lot of forum members make the "Discovery" that their fan clutch is not working well, which can easily make things over heat at low speed or idle. When engine is hot, and turned off, fan blades should not freewheel even a whole revolution. When cold start, fan should "roar" as fan internal oil warms up. Mine pulls enough air at cold start to spin the electric fans, even though they are turned off. The tech section has a cheap fix using a Chevy fan clutch for about $50. You did not mention the speed of your 30 minute drive, if above 25 mph, I would also suspect coolant level or some new obstruction in the radiator, or trash between radiator and condensor.

 

Buzz,

In my case the fans never turn on. Not when hot, not with AC on and not after. Just plain dead. That leads me to believe the motors are kaput but I was just curious if there was a way that a bad connection or relay or fuse could kill them.

As for my fan clutch, I believe it to be in good shape. When cold the fan spins but not loosely and when the engine is warm it barely spins (appox 1/8-1/4 turn).

I will most likely need coolant flush in addition to my fan problems. Is it better to have a shop do a flush or is that a waste vs doing it myself?

 

Those fans are for the A/C system. They are condensor fans. They are used to cool the freon from the gas stage into the liquid stage. They should only come on when the A/C is on. They do not help cool your engine. The fans are connected to the compressor clutch. When the clutch engages the fans should be on and running. If your compressor clutch is not engaged and spinning then you have other issues with your A/C system. HVAC certified over 10 years.

 

Are you getting 12V to the fan harness when you think they should be on? Do you have a good ground? What happens if you supply 12V straight to the fans?

 

They will in fact help cool your engine even without the AC on, and there is a thermostatically operated switch to turn them on if the engine gets too hot.
That said, if they are coming on with the AC off, you have cooling system problems because a well functioning cooling system doesn't need them.
If they aren't coming on at all, it could be the fan motors, or something in the circuit.
However, I'd address the cooling system issue before worrying about the AC fans.

 

Actually I don't have a meter to test this. I will try to borrow one so I don't spend $130+ on two fans that may not work once installed.

I will also find someplace to check out the rad and have it flow tested. What kind of $$$ should I expect for best case (flush) or worst case (re-core or rodded or whatever they do)?

I am definitely on a budget at the moment.

 

Check the tech section for cheap fan replacements.
Take a screw driver and try and spin the fans by hand, if they are bad the bearings will most likely be seized and they will not turn at all.

 

Per the Electrical Troubleshooting diagrams from the RAVE documents, section K5:
The fans should come on when AC is on and AC blower is on any speed. The fans should also come on in the event the coolant gets to 212 F (100 C), even if AC is off. If engine is off, but coolant is 110 degrees C AND fuel temp is above 70 degrees C fans will come on for about 10 minutes to cool things down. There is a fuse for the fans, it is inside the box under the hood, F3, 30 amp. The fans are controlled by relay K109, which is controlled by several things. It is under the fascia, near the blower motor, but so are several others. See RAVE. I'd check the fuse first, and like Spike said, give them a spin. If fans are not coming on, your HVAC should not be turned on unless you are moving at highway speed, to save other components.

 

Per the Electrical Troubleshooting diagrams from the RAVE documents, section K5:
The fans should come on when AC is on and AC blower is on any speed. The fans should also come on in the event the coolant gets to 212 F (100 C), even if AC is off. If engine is off, but coolant is 110 degrees C AND fuel temp is above 70 degrees C fans will come on for about 10 minutes to cool things down. There is a fuse for the fans, it is inside the box under the hood, F3, 30 amp. The fans are controlled by relay K109, which is controlled by several things. It is under the fascia, near the blower motor, but so are several others. See RAVE. I'd check the fuse first, and like Spike said, give them a spin. If fans are not coming on, your HVAC should not be turned on unless you are moving at highway speed, to save other components.

I had my rad flushed and rodded out for $65 (I took it out and carried it to them). This price was half what a large shop charged, I went to a small indy place that is out in the country, his main business is tractors and farm /construction gear, so he does not charge much for baby radiators. I had tried flushing it myself, just wasn't getting it done.