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Thread: Cooling fans with No Air Conditioning

  1. #1
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    Default Cooling fans with No Air Conditioning

    My RamJet 350 24x conversion required me to change out my mechanical clutch fan for clearance reasons with the intake piping. I am using a LS1B, 2001 camaro manual calibration with OS 12202088. No A/C in this FJ40! I wired C1 42 to control fan 1 relay, and C2 33 to control fan 2 relay. My fan is a single two speed Derale. My thought was "Fan 1" for low speed, "fan 2" for high speed. The setup worked great on the bench manually triggering the relays. I went through the calibration and set the fans to Series, then in Engine DTC set "Not Reported" and "No MIL" ed all the A/C stuff. Got "clicking" on the relay, fan ran but relay was getting really hot. Swapped in several different relays (old 5 pin kind), same thing. I am thinking it has something to do with the A/C parameters, but dont have a clue. I didnt pin any AC stuff on the PCM so maybe something A/C needs to be grounded to fake A/C????? Changed the calibration to Single fan, now relay "clicking" is gone, but now low fan runs upon engine start and wont shut down, while high speed comes on as calibrated. Does the ls1b output a PWM signal which is causing the relay rapidly clicking on and off?? Thanks for help!
    Last edited by Dcon; July 19th, 2021 at 06:09 AM.

  2. #2
    Joe (Moderator) joecar's Avatar
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    Post schematic of your wiring, and pdf user manual for the fan.

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    Thanks joecar for the reply, i really appreciate it. I got her to work finally after hours of reading on the forums. Always a wealth of information here, just need to find it. Anyway, I didnt open my old calibration to confirm, but im pretty sure i had the on/off temperatures switched and was confusing the PCM. ie on at 195, off at 200. Anyway, I set up the series fans at if I remember right; Fan 1 on 195, off 190, fan 2 on at 200 off at 195, key off run at 200 for 60sec and some mph settings too. i also put in some AC pressure set points someone else had posted. I dont have the file open, so I dont have the exact settings in front of me. It works perfectly as programmed now! No more clicking hot relays! Now I get to start from scratch and full flash a new OS. The camaro tune I used (2001) has a different OS than the L31 express van I need to segment swap from to keep tuning this thing. I found a 2002 camaro file with the same OS. We will see how this goes, I already bricked one ecm full flashing it.

  4. #4
    Joe (Moderator) joecar's Avatar
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    Good job on getting it going

    No need to full flash (you are not changing OS)... you should be doing cal-only flash.

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    Again joecar, thanks. I thought I would be able to just segment swap the engine operation of the L31 van tune into the Fbody tune and I read that the OS needs to be the same. , but still not sure if that will just cause more issues so i didnt try that. I took the chance and just did the full flash to the 2002 fbody. It went fine. I made all the same, changes, modified bank assignments for the gen 1 firing order, cleaned up the DTC's, set up fans etc. I compared the 2001 and 2002 fbody tunes, there were some differences in engine operation. It started up, but was running rough with the 2002 fbody tune. I went back in and set my injector flow to the constant L31 setings, that made a huge difference in idle and throttle response. I have yet to take it for a drive. I am all new to this and learning as I go. I have been doing a ton of reading and slowly getting a better idea. I am pretty sure I need to go in and make spark and fuel corrections, but im not sure how...yet. Back to reading!

  6. #6
    Joe (Moderator) joecar's Avatar
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    Ah, segment swap, of course.

  7. #7
    Joe (Moderator) joecar's Avatar
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    The 2001 and 2002 F-body tunes are almost identical (I ran the 2002 tune on my 2001 TA when it was still new/stock).

    Use all the L31 injector tables.

  8. #8
    Joe (Moderator) joecar's Avatar
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    2002 F-body spark tables are good, check for knock retard.

    Also, use 2002 F-body PE tables/parameters, these are much safer than truck ones.

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