Electrical Fan Spins Intermittently

Discussion in '1994 - 1995 Specific Tech' started by JordanB21, Oct 4, 2012.

  1. I think I figured out my problem. I think my fan motor is bad. I believe when the fan stops some times it lands on a bad pole. If this happens it can't energize itself into operation. A bump in the road seems to jar it into operation sometimes. When I started it up earlier from dead cold, I turned the A/C on and ran it for 5 minutes and the fan wouldn't come on. I shut the car off, went to grab a test light and the stupid fan was working again when I restarted the car.

    I will wait until this happens again and test the leads going to the fan. If they are powered up then the fan motor is bad. Also, when I shut the car off the fan motor was making some grinding and high pitched scratching sounds as it was spinning down.
  2. Well, disregard the last post. I think my CCRM is the culprit. I just went out and the fan wouldn't operate, so I checked the leads going to it with the A/C on and nothing. I let it run 10 minutes to see if it would come on and nothing. I checked for ground at pin# 17 which controls the high speed fan operation and it showed a good solid ground through my test light.

    So, the computer is telling the CCRM to turn the fan on and it is not obeying.
  3. I would not use the stock triggers to control the fan (pin 17, etc). The settings are too high and could be unreliable. I would use an aftermarket switch or quality controller. They are few and far between however. A quality controller is the best option IMHO however.

    Mark, if you decide to keep the stock style of control (using the low and high speed triggers from the CCRM but with your own relays), you'll need 3 relays. Two should be 50+ amp units for reliability. The third can be a 40/30 SPDT, as it's just controlling the other two.

    Easier is to use the low-speed trigger for activation of high speed (no longer using low speed), and add a lead from the LPCS input from the HVAC controls (this does not cycle like the output does) to the same relay, with a diode on each leg to prevent back feed. The fan would come on naturally at the low-speed factory temp, and the AC would also trigger it - high speed in both cases.
  4. I still had the 99 V6 CCRM left over from my swap and inside it were the same 40 amp bosch relays as were in my 94/95 CCRM. So I carefully desoldered the one I thought was the problem (since pin 17 lead to it I figured it controlled the high speed fan) and then soldered one from the 99 CCRM in it's place. Put it all back together and so far so good. The fan comes on now about 20 seconds after startup if the A/C is on. I cycled the car on and off about 10 times to verify and it's working great. I even let the car come up to temp without the A/C blowing and the fan kicked on like it was supposed to.

    The relay inside the CCRM I changed was the one in the center. Wasn't too bad actually but a little radio shack soldering iron won't cut it. I had to break out my old Weller Professional to get the solder to melt.
  5. Oh, and the 99 V6 CCRM would have probably worked but it was clearly missing the high speed fan relay. Also the newer CCRM was a much better design, I wish it would have worked.
  6. does it do it when the car isnt running?
  7. I've never seen Mustang fans come on while the car is off.
  8. never:p
    me neither, unless...I ran jumpers from the battery to the fan, forever. ;)
    course my car battery would be dead in a minute.

    I guess I should update you guys, I haven't had time to test the pin out that hissin noted, school, girlfriend (ish?), work, so on. Busy kiddo here:p

    Right now i'm struggling to find time to mount rims andtires on my fox, I did one today -___-.
  9. So. I finally went out and did some tests, I have a friend own owns a salvage yard and let me borrow a bunch of CCRMs for testing, 3 code Rs (two were different), and a code P. None of them made the fan click on, so I doubt it's the CCRM. I tested jumpers to the fan again, it spun, high and low worked. And I tested the male end that plugs into the fan for voltage while the car was on with both a test light and multimeter. The multimeter read a clean 13.3 steady volts (1 volt below the battery's) at the high speed fan (the a/c was on and the car was pretty hot).

    I'm out of thoughts now. :(
    I tried testing what hissin said, and I had trouble doing this because I couldn't tell if i was making contact from the back of the pins or not, but the constant 12v ones did read 12v when the car was off (easier to test on the opposite end, pins 3 and 4 and 14 I think?).

    Again, nor low or high speed fan is coming on. and all five of the ccrms I used allowed the car to turn on so the fuel pump relay across the board is the same to some extent.
  10. If the triggers are not exciting the relay(s) or the relay(s) are bad, the fan won't energize (only naming two possible issues - the others are less likely).

    Did you try testing the triggers at least (if you can only test one, test Pin 17)? If backprobing is not working, you could pierce the wire with your meter lead so you can get the testing done. You can seal the hole later on. If grounding pin 17 makes high come on, you could at least install a manual switch and have some fan control.
  11. Triggers referring to which pins?

    I'll have to work at it again tomorrow, too dark now. But I should test pin 17(thought it said it was pin 15 for ground) for good ground then or by grounding it out?

    I did test pin 15 for voltage and it read in mV to around .5 to .7 volts.
  12. Low speed trigger: 12 volts to CCRM Pin 14 at or greater than 208*F

    High speed trigger: Continuity to ground at CCRM Pin 17 with the AC on or at/above ~228*F. This is the wire you can try grounding to see if high speed will energize. If so, you can add a switch.
  13. I can defiantly do the test on pin 17, I do run the fan on high for testing and so on. I'd prefer not to add a switch, fix what's there (the car i'm keeping as factory as possible right now).

    Pin 14 is harder to catch because of getting it upto temperature, without reaching 228*F. But i'll try both triggers again. Thanks Hissin
  14. If you can get the fans to come on by triggering the CCRM then that means it is good and there is a fault between the computer and the CCRM.
  15. What would you suggest this to be, on the back end, the actual computer, temperature sending unit, orrr (all I can think of :p)?
  16. you have to eliminate the CCRM then you work backward from there. If you unplug the ECT sensor the high speed fan should come on by default.
  17. why did I forget about this? That'll be the first thing to do! I could always do that and just have the fan run forever till it burns up.
  18. I believe low speed is supposed to come on with the ECT disconnected.

    Losing the trigger command is not uncommon. Most folks don't bother to fix it since the stock temp settings are so high anyhow. They go with an aftermarket controller or switch.

  19. Or get it tuned to come on earlier like I did :)

    Jordan, don't go around leaving your ECT unplugged, the computer will be blind to how warm/cold the engine is causing your AFR to be way off, fuel economy will go to crap!
  20. What's weird about mine is I have fixed the relay inside the CCRM and it has been working, but sometimes the high speed fan is lazy after I first start my car with the A/C on. Yesterday the computer allowed my engine to get over the halfway point before finally triggering the fan to come on. It immediately went back down to normal. I have no idea why it's doing this. If I trigger the CCRM manually it works every time.