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Burning out High Speed on cooling fan

4K views 44 replies 6 participants last post by  95 Laser GT Vert 
#1 ·
Burning out High Speed / How to test fan speed??

Here's the history; last summer the car was overheating and discovered that the high speed wasn't coming on. Local supply didn't have the correct fan so I had to go to JY for sourcing a replacement. Verified the high speed was working and all was good for 6 months, until last week. I figured that it was just the inevitable sequence of an old JY part.

Got the new fan motor from NAPA, tested by applying 12 volts to middle tab then outside tab with proper response to low and high speed. Four days later and I'm back to one speed when applying voltage directly to fan harness on both tabs.

That's three motors with high speed burnt out in 6 months. So how is it that I'm burning out the high speed with no visible signs of wires or harness getting hot on any of them?

Alternate question, has anyone noticed different pitch on fan blades?? What's the reason for this??
 
#3 ·
Connector looks fine, no evidence of heat.
 
#4 ·
Picked up a new fan and out of the box I only have one speed, am I testing incorrectly? Black wire to ground and middle lead to plus side, motor runs at what I assume is low speed. Add outside wire to plus side and speed does not change, so is this fan bad??
 
#5 ·
As described you should be getting both low and high. Are you certain the fan motor is a 2 speed piece?
 
#6 ·
Sure as I can be. Fan came from NAPA as a direct replacement for the Ford number. Don't make sense two motors in a row that fail virtually just out of he box.
 
#8 ·
There may be a CCRM issue but he couldn't get a high fan by applying power to the fan motor at the connector. I'm wondering if the 3.8L is a two speed fan and if it isn't did they give you the wrong replacement part?
 
#12 ·
The part number on the fan is listed as a direct replacement on multiple sites, so I'm thinking I have the correct part.
 
#11 ·
I've got a scanner that I can use for that, thanks for verifying. I wasn't sure if both speeds came on.
 
#13 ·
I disassembled the old fan motor and I find that both low and high speed tabs are directly connected once it goes past the connector plug. So how does the motor go from low to high, is it seeing additional voltage somehow?



Here's a pic of the windings, everything looks good unless you guys see something I'm not.

 
#14 ·
Ran the KOEO test and got two cycles of 11.5v, so it appears the system is working properly.

Can someone explain for me exactly how the motor goes from low to high speeds?
 
#16 ·
Can you give me the pointers to check the resistance? Duh, you're talking about checking motor... I can do that...
 
#17 ·
1.2 ohm on each post
 
#18 ·
So if the resistor in the harness sets the motor speed how did I get two speeds when previously checking the other motor?
 
#21 ·
Second owner, I've had the car since '96. I have verified through my own witnessing of the high speed kicking in while the car was running and testing prior to installing the replacement fans.
 
#24 ·
Diagram very helpful, but it looks like the fan speed is just controlled by voltage from the CCRM, is that correct?
 
#23 ·
Yes, the first new motor I tested and got both speeds prior to installing into the car, that motor lasted the week. The replacement for that motor failed the bench test out of the box. I'm currently trying run KOEO test with this motor installed to read voltage across both each hot lead.
 
#25 ·
Engine running at 180* first speed kicks in with 13.9 volts on red wire
Engine running at 190* with 13.9 volts to orange wire but no response from fan motor, stays at same speed. This would be easily noticeable if it had turned on since the motor is simply sitting on the top of the grill and the increased torque would have shifted the motor.

Done everything I can think of to see if it's something with the car, but it does appear this second motor is indeed not good.

Any other ideas??
 
#26 ·
the CCRM is just a relay box.

You have a single speed motor.

you can see the two leads join into one.

you have a single speed motor, you need a two speed motor if you want two speeds.
 
#27 ·
The pic with the leads is of the two speed motor that's been in the car since last summer, which was an exact replacement of the original.

Picked up a different motor from an independent parts store, the info page from inside the box says it's a direct replacement of a two speed fan that has been converted to single speed. The number of windings in the motor were noticeably fewer than my original motor so I chose to continue my search...
 
#28 ·
we need to clear a few things.

the CCRM does not lower voltage, its a relay box.

the fan in the pic is a single speed.

bench test the fan with a battery and you will see.

there were recalls with your mustang.

one remedy was a circuit breaker, or new fan,,, this was from bearing overheat.

if you think you have a two speed fan, test it with a battery. you do not need a scan test.
 
#30 ·
I don't know what you think you need to clear up..

I never said the CCRM lowered the voltage.

I have installed two replacement fans within the last 6 months, first was from salvage yard and second two weeks ago was from NAPA. Prior to installing fans I did run the bench test with a battery and with the application of 12V to the second leg the speed increased, and I provided this evidence to the service guys at NAPA this morning on the alternate motor (has a roll pin in the shaft to lock the fan into position).

I appreciate the knowledge you share while helping others here, but your insistence that this motor is single speed is simply incorrect. I can't bench test the motor that is pictured because I took it apart after it failed, but I guarantee I did before installing.

Yes, this car had the recall and they installed the breaker, I was unaware of the fan change but that would explain the different pitch on the fan the I got from the salvage yard.
 
#29 ·
another myth

is the fan comes on when you turn on the a/c........this is WRONG it does not.

the fan only comes on via input from the PCM, coolant temp and or discharge pressure in the a/c system.
 
#32 · (Edited)
Don't know if I can add anything new but here it is.

Low speed fan
* At 205 degrees F, my processor grounds the relay for the low speed fan and it comes on.

* At 200 degrees F, my processor removes the ground from the low speed fan relay and it goes off.

High Speed fan
* At 212 degrees F, my processor grounds the relay (this is a different relay) for the high speed fan and it comes on.

* At 207 degrees F, my processor removes the ground from the high speed fan relay and it goes off.

More Information
1) Both relays for your low and high speed are never on at the same time due to high current draw.

2) If your fan has 3 pins (ground, low speed power and high speed power) it's a dual speed fan.

3) The low speed has less windings than the high speed and that's how you get you speed changes......it's in the windings.
 
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