Electric fan problems, again...

[swaq]

Lately I've been having trouble with overheating. I have a SPAL fan controller attached to dual Flex-a-Lite fans. The first fan is wired through the controller for variable speed. The second fan is operated by the controller via a relay, and only turns on when the "High" temperature is reached.

Here is how my daily commute has been going recently:
- Morning: 15 mile, 30-40 minute commute, still not too warm out. Both fans run at full speed when the high temperature is reached.
- Evening: Coming home, usually 5 minutes or so longer due to traffic. Temperature aroune 80 degrees F outside. The first time or two that the high temperature is reached the fans kick into full speed. After that the high setting does not kick in again and the car starts to overheat.

I have opened the hood while the car was running and was hot enough that the high setting should have kicked in and noticed that the fan controller had the low speed light illuminated. It was as if it didn't think it was hot enough to turn the fans up to full speed.

If I turn off the car while it is overheating and the fans aren't going at full speed, then turn the key back to On without actually starting the car back up the fans will kick in at full speed.

Please help, this problem is making me want to sell my car and buy a Porsche. The wife says, "You are not selling the Supra to buy a Porsche!"

 

[jdub]

Check the wiring for good connections...if good, either your temp sensor is FUBAR or the fan controller is kaput.

 

[swaq]

Check the wiring for good connections...if good, either your temp sensor is FUBAR or the fan controller is kaput.

I just rewired this thing last summer, including a new fan controller. Temp sensor isn't something I thought of... I don't understand why it would work fine for a while and then stop. Or why it works when the car isn't running...

 

[Rennat]

where did you place it in the engine bay? i remember reading about them "over-heating" and it caused a bunch of problems... which is why i just got a switch and hard-wired it.

 

[A-to-the-J]

just switch back to the clutch fan. it's 10000+ times better

 

[suprabad]

just switch back to the clutch fan. it's 10000+ times better

uhhhhhh....no it's not.:nono:

I have run dual electrics for 2 1/2 years with absolutely no problems.

Quieter, flows better than stock fan, no parasitic power drain on engine and only runs when the electric thermostatic control senses the temp justifies the fan (adjustable).

The problem is either poor and/or undersize wiring, or mismatched and/or poor quality components.

Start from scratch, do it right, with the right parts and wiring, and you will not have problems and you will reap the rewards of electric fans.

Buy cheap shit, do a sloppy job, and you'll create a nightmare.

 

[thelonerider]

This is fishing, but could a sticking Thermostat be a problem as depending where the fan sensor is, it could be reading the cool side of the Rad and the temp sensor is reading the hot side of the engine? When you switch off the engine the heat expansion of the coolant causes the thermostat to push open or transfering heat to the Rad thereby activating the fan sensor... Like I said, just fishing here....

 

[swaq]

The controller is attached to a bracket on the radiator. I have an aluminum radiator.

I do prefer the look and quietness of the electric fans, but if it takes the re-installation of the clutch fan to keep my car from overheating in the Tucson summer then that's what I'll be doing.

I redid the wiring when I replaced the fan controller last summer. It should all be the correct gauge.

The fan sensor is on the hot side of the thermostat, I believe.

 

[turbodriz]

I have the same set of fans . I just have them hard wired to a switch in the car. I know it is a little ghetto but it never fails. I start the car and hit the switch and waalaa! Or you can wire it to your accessory and when you start the car it comes on.

 

[swaq]

I have the same set of fans . I just have them hard wired to a switch in the car. I know it is a little ghetto but it never fails. I start the car and hit the switch and waalaa! Or you can wire it to your accessory and when you start the car it comes on.

I've been considering that...

 

[swaq]

So I went ahead and just wired up a manual override switch for now so that I can keep driving her. It is able to keep it under operating temperature when running full speed, but not by much. Maybe there's something else wrong that I'm missing...

 

[PCguylovesSupra]

I have the same dual fans, I had the wired into the ignition, so the fans are on when the car is started and off when the car is off. No issues.

my .02

Scooter

 

[jetjock]

Perhaps related:

Guy recently brought me a car with what he described as a "wierd" overheating problem. Temp would begin to rise only on the highway, only after driving a while, and only when the ambient was above 70 degrees F.

He'd already replaced the thermostat. The tip off was when he mentioned how the engine ran at the same temp with or without it, that is at a normal temp during times the engine wasn't beginning to overheat. This demonstrated no reserve cooling capacity which, contrary to popular belief, the stock system has a fair bit of.

A scan of the radiator with my IR gun showed decent overall cooling from top to bottom but the center was at 100 F while the sides were 200 F. You could put your hand on the center in front of the fan. Needless to say a new radiator solved the problem. I later cut the tanks off the old one and found the center section plugged in the middle and solder bloomed shut on the bottom. The radiator was less than 3 years old and looked near pristine under the cap. It was fine on either side of center.

Another thing to look at is the bottom radiator hose. If it's old the reinforcement will be weak. This will cause the hose to collapse under water pump suction. The same "highway only" symptoms will apply but the ambient temp won't matter.

On another note I just changed the coolant filter on my car. You would be amazed to see the crap that was in it and this is on a well maintained cooling system.

 

[swaq]

I just installed my new aluminum radiator in the spring last year. I had a shop do a coolant flush with Zerex G-05 and they pressure tested the system as well.

There is a coolant filter? How hard is that to check/replace?

 

[jetjock]

Just thought I'd throw that out. Still doesn't mean the core is clear though. Might want to at least feel it in various places. And pressure testing won't find blockages.

There is no coolant filter. You have to add one. At least you're using G-05...smart move.

 

[Nick M]

uhhhhhh....no it's not.:nono:

Quieter, flows better than stock fan, no parasitic power drain on engine and only runs when the electric thermostatic control senses the temp justifies the fan (adjustable).

The problem is either poor and/or undersize wiring, or mismatched and/or poor quality components.

Start from scratch, do it right, with the right parts and wiring, and you will not have problems and you will reap the rewards of electric fans.

.

If what you said is true, why don't heavy trucks with much more heat to dump use a set up like you claim?

 

[swaq]

I think I'm leaking coolant from my water pump. There's a splash marks all over the timing belt cover in a spray pattern...

 

[WhtMa71]

How long has it been since the waterpump has been replaced? Might be time for a new one.

 

[jetjock]

You have a problem unrelated to the fan. That said after everything is checked put the stock fan back on. Really. Rebuild the fan clutch or buy a new one before you do.

One thing I didn't touch on in the other thread but should have is that most people overlook how the cooling system's total capacity operates over a very narrow range, e.g. how it goes from 0% to maximum capacity in only 15-20 degrees and how that makes the wax pellet t-stat the single greatest restriction in the system. The implication of not having the electric fan t-stat correlated to the wax t-stat (or worse, running the fans continuously) should be obvious but apparently isn't. It's why fan clutches have a calibration provision inside them.

But hey, also feel free to do anything you want

 

[Facime]

I too agree with the SM experts and suggest going with the stock mechanical fan. Its worked for years to do the job it was designed to do. That being said, and knowing Tucson weather and traffic, a helper fan (maybe a pusher?) or wiring your AC/Aux fans to a manual over-ride might be an idea worth looking at if you go back to manual.