fan relay problems

Discussion in 'Fox 5.0 Mustang Tech' started by QUIKSVT, May 23, 2006.

  1. So, I've had this cooling issue with my 95 cobra. Stock cooling system. It seems the low-speed fan won't come on, it waits for the high speed fan to kick in. It comes on when the temp needle is on the A-L area of the guage, brings it way back down. I unplug the fan relay plug and reconnect it and it works properly, kicks in the low speed at straight up and down on the guage, but it only does it for a little while before it reverts back to its same old tricks. Any ideas??
  2. I'm having some issues myself - Saleen0679 has been helpin me try to figure them out. :nice:

    Are you unplugging the CCRM connector (that's where the fan relays are housed)?

    When you run self diagnostics, does the low speed fan cycle?

    You should see the low speed come on at 208*F per a real gauge in the stock temp-sender-port. Look for 12 volts at Pin 14 on the CCRM at or above these temps (but before ~225*F). If you have that, I'd check for output from the EDF-relay-control to the low speed relay. If you have A but not B, the EDF relay control is something to look at.

    More info from you will help shape what other ramblings I might come up with. :rlaugh:

    And welcome to the boards!
    Good luck.
  3. Yes, I am unplugging the CCRM connector. No codes are being thrown, no CEL... I have been telling myself the stock guage is close enough, but I'm leaning more towards "its a worthless waste of a needle" ... Its all over the damn road.

    EDF Relay control?

    Ramble more, I could use all the help I can get.
  4. You're right - the stock temp gauge is fairly worthless. At best it's hysteretic. Even tossing a cheap parts-store guage on there till you get the issue sorted out would work.

    The EDF relay control is what the low speed fan signal goes through before it energizes the relay inside the CCRM.

    The two things I can think of right off the bat: for right now, I would install a manual fan switch for the low speed fan. This way you dont have to let it bake and hope the fan cools it off (and this might help save the high speed fan connector, which is problematic). High speed doesnt kick on till ~226*F - too hot for my tastes.

    To do a low speed fan switch, you switch fused 12 volts to Pin 14 on the CCRM.

    I'd do the quick tests I mentioned in the first post - that'll help narrow it down a little (so you can see if the PCM is telling the EDF to energize the fan, and if the EDF is telling the low speed relay to energize). Your low speed relay might have pooped out, but only testing will tell.

    I'm too tired to keep typing - if you can do a little testing and post back and we can work through it some more. I cant keep my eyes open.

    Good luck.