High speed fan not working

[Kryo-Genik]

I cut the resistor out and soldered some decent gauge wire across the terminals on the back side. That way the connector still plugs into the resistor housing and the housing clips into the fan shroud like stock, just no resistor.

Thats a pretty spiffy way of doing it.
Im in the desert and there are times where I am curious if my fan is even working, with a 170* t-stat I still see temps like 226. And there have been a couple of times where ive actually seen my temp gauge peg out at 253 degrees which meant a shut down and wait period. So either my fan is bad or something else is up....ive been trying to figure it out

 

[mustang john]

When that happens pull over and pop the hood and see if the fan is running or not.

 

[Kryo-Genik]

When that happens pull over and pop the hood and see if the fan is running or not.

That is what I did one of the times, it was running...or at least sounded like it (was hard to see it). I got a new 170* tstat and a new waterpump (swapped the stocker to a bosch unit as the stock one was leaking around the weep hole). I dont think my radiator is jacked...im thinking its the danged fan.

 

[Kryo-Genik]

I believe the fan is stupid. Water flows through the rad fine. motor spits coolant with ease when testing the bosch water pump. The fan turns on...but isnt all the loud and produces a "breeze" But if im driving with the A/C on she will hit 226 degrees and then just climb to 253 degrees within minutes. Ive tested the t-tast and it opens when put into a pot of water at 170 +/- degrees. And when the t-stat is in place the coolant hose on both sides of the t-stat are hot. When the stock t-stat died one side would be hot and the other cold.
So does anyone got any other idea for these temps?

 

[MalcolmV8]

I believe the fan is stupid. Water flows through the rad fine. motor spits coolant with ease when testing the bosch water pump. The fan turns on...but isnt all the loud and produces a "breeze" But if im driving with the A/C on she will hit 226 degrees and then just climb to 253 degrees within minutes. Ive tested the t-tast and it opens when put into a pot of water at 170 +/- degrees. And when the t-stat is in place the coolant hose on both sides of the t-stat are hot. When the stock t-stat died one side would be hot and the other cold.
So does anyone got any other idea for these temps?

What are you using to get those temp readings? Datalogging what the ECU sees or aftermarket gauge?
If you're unsure of fan performance while sitting in the driveway take an IR gun and get readings on your radiator at the inlet and outlet and see if there's much of a temp drop if any.
Air pockets in your cooling system?

 

[03cobra#694]

What are you using to get those temp readings? Datalogging what the ECU sees or aftermarket gauge?
If you're unsure of fan performance while sitting in the driveway take an IR gun and get readings on your radiator at the inlet and outlet and see if there's much of a temp drop if any.
Air pockets in your cooling system?

My thinking, or the fan is junk. It get hot as crap here in the summer and my car rarely goes over 195*, a/c on at idle at a light or rolling down the highway. I'm running the 170* stat and revised fan settings.

 

[Kryo-Genik]

What are you using to get those temp readings? Datalogging what the ECU sees or aftermarket gauge?
If you're unsure of fan performance while sitting in the driveway take an IR gun and get readings on your radiator at the inlet and outlet and see if there's much of a temp drop if any.
Air pockets in your cooling system?

Air pockets are possible, however ive drained and filled it twice on a jack stands to keep the nose up, and filled through the bung on the coolant crossover. I havent used an IR gun yet, Im getting the temps during my datalogging sessions. So either something is up or Im doing something wrong ?

 

[MalcolmV8]

Air pockets are possible, however ive drained and filled it twice on a jack stands to keep the nose up, and filled through the bung on the coolant crossover. I havent used an IR gun yet, Im getting the temps during my datalogging sessions. So either something is up or Im doing something wrong ?

Check with an IR gun and see if any cooling is happening across your radiator. No jacks or jack stands should be required. I've filled these cars up countless times just sitting flat. Remove the cap off the over flow reservoir and remove the cross over coolant bung. Add fluid in the cross over tube till it's going to come out the coolant over flow bottle and then put the cap on there. I use a funnel that fits snug in the cross over tube's hole so if some fluid comes back up it just goes up in the funnel and can go back down. Start the car and often the fluid level will drop some (not always though). Keep adding fluid till it's not taking anymore. No need to wait for it to warm up now because as it does it'll just start pushing fluid out the cross over. Just put the bung in and take it for a short drive. Get things heated up. Let it cool (going through heat cycles) and then check the fluid level in the over flow bottle and add as needed. That should be it unless you have other issues going on.

 

[mach1z]

Any updates? I am having the exact same issue. Fan works at low but as soon as i turn the AC on the temp spikes up.

 

[Banshee06]

My 2003 Mustang Cobra is doing the same thing.
My High speed wont come on even when I turn the air conditioning on. Just the Low speed. So when I am in stop and go traffic with the outside temp over 90 my engine temp goes up and only pulling over and letting it cool will help.

 

[hotcobra03]

on mine..

I've found issues on the connector with fan side,barrels moved back..fan was on/off.

I also had radiator this last time.
didn't think an everyday driver would but..

I too spent hours chasing cooling issue..

last test was adding water over front of radiator..

this test was the only way to lower it after 220..

sve radiator was installed..instant low..

I see 178 while at 70mph over 100deg outside..with or without ac,on

 

[hotcobra03]

I'm confused by how my fan is not switching to high speed with that resistor blown. You'd think that's for low speed only. Unless high speed is a combination of power to both the low and high speed circuits. I'll find out in a couple days when I get the replacement if my high speed starts working again or still an issue.

I can't find a wiring diagram for the fan so not sure how that resistor circuit is used exactly.

 

[Banshee06]

View attachment 1502420

Cool I needed this!

 

[94 Cobra R]

@MalcolmV8 - Curious, what ever became of this and that relay? Does it control the low speed??