Electrical Cooling Fan / AC Issue, please help!

Discussion in 'SN95 4.6L Mustang Tech' started by stprorolla49, Apr 20, 2013.


  1. stprorolla49

    stprorolla49 Active Member

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    I'll try to give the abbreviated cliff notes version of the story, please bare with me. Keep in mind these have been very intermittent issues.

    Last summer I started having issues with my cooling fan. I was blowing fuses randomly, the cooling fan wasn't working, a/c was causing the idle to surge and wasn't blowing completely cold all the time.

    I did a TON of research before throwing parts at it, ended up replacing the cooling fan, low speed resistor (mounted in fan shroud), and the coolant temperature sending unit. The sending unit was the last thing I changed after I threw a CEL, which I checked on my code reader and it said "Coolant Temp Sensor".

    I replaced the sensor and all was well. No issues sitting in traffic, no overheating, a/c worked as it should, etc etc. This was late last summer, after which I racked up about 500 miles before storing it for the winter. I took it out of storage last month and have since put on over 1000 miles, all trouble-free, happily boostin' miles!

    Fast forward to yesterday, I was driving back to work from lunch and noticed my Autometer was around 220 degrees. I turned on the a/c to see if 1.) it was blowing cold, and 2.) it kicked the high speed fan on, neither of which it did. At this point I limped it another half mile back to work and popped the hood where I discovered what I just mentioned, high speed fan was not running, and a/c wasn't blowing cold. The a/c compressor was also making a slight whirring sound when engaged.

    At this point I'm just at a loss. I have done massive amounts of research, and can't afford to just throw parts at the car. I'm starting to think it could be the CCRM since that controls the fans, a/c, and fuel pump. ALSO, srthandz posted in my build thread on another site saying when running an Aviator pump, Kenne Bell recommends using their 40amp BAP rather than the 20amp BAP that I have because the Aviator pump draws more current. Not sure if this is true or not since many people run Aviator pumps with 20amp BAP's, but could this be a contributing factor in killing the CCRM relays? Drawing too much current?

    Keep in mind, I never had any issues before I installed the blower, and these issues are very intermittent which makes diagnosis impossibly hard. My combo (of which it pertains to this issue) is as follows:

    Novi 2000
    Intercooled
    Aviator pump
    KB 20amp BAP
    39lb '03 Cobra inj
    VMP HPX MAF

    Any help would be greatly appreciated!!
  2. WrenchThrower

    WrenchThrower New Member

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    maybe the extra current from the pump is overheating the surrounding relays?
    I would try to find a way to re-engineer the whole fuel pump circuit so that it is on it's own with the use of relays or run a return style system., or something similiar for the cooling fan.
    You could even consider using a temperature probe ground system to trigger the fan on and off, I used those on old carb cars with great success ditching the crank fan.

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