High Spd Fan supposed to come on with A/C Max?

Correct - people say high speed should come on with Max AC. Only my low speed came on, so the car would run hot eventually while in traffic.

I would check the fan wiring directly (when low speed signal is sent, Pin 14 on the CCRM gets 12 volts. When high speed is on, Pin 14 is dead and Pin 17 is grounded via the computer). Testing at the fan connector tells the end result real fast. IIRC, the top fan connector is ground, middle is low speed and bottom terminal is high speed (birdseye perspective).

Good luck.

Is there not a self diagnostic test that is supposed to turn on both fan speeds?

If so ... envoke that one and see if both speeds work good.



Grady

yellowstang1994 said:

Both speeds do work good with the test. The correct fans come on when they are supposed to while the car is running at about the right temps. It's just when you turn the A/C on that the low spd comes on instead of the high spd.

Click to expand...

Now that I think about it ..............

Seems like I remember doing that very same thing one day and noticed the fan came on but it did not sound as loud as I thought it should.

Just the kind of thing you are asking about

Kinda makes me wonder also if ... it was only the low speed

Grady

I traced schematics and narrowed it down to what I believe was the PCM itself not switching from low to high with the AC coming on. I hated the stock set up and it was an excuse to install a Dc Controller. It's an AMAZING unit that I had wanted to try for a long long time and this was the excuse I needed. No more fan switches or anything.

The default is for low speed to come on. The computer has to be actively participating to shut low speed off. This is a safeguard and why the EDF control is present. But the PCM needs to interact to kill low and allow high speed to come on.

If you keep noticing that it does switch from low to high speed, it might be normal. I'm pretty sure there is a time lag in the switching from low to high and vice verse. I'd observe it further.

If you want all the EDF and control stuff, I can sort through it (I already forgot a lot of what I learned - it's pretty confusing to a simpleton like me). I would want to find the reason for the EDF fuse blowing. Because of the EDF RC, a bad fuse might be confusing the computer (the EDF RC is a solid state device that I couldnt find much info about, and since it's solid state, I couldnt infer how it works).

Random thoughts. Good luck.

Just post up or PM if you feel like running through stuff - I'll go through the notes I made and see if it helps.

Gotcha about the EDF fuse. I cant remember what it should have - if I find that it should have power, I'll post.

I have always heard that the high speed fan is supposed to come on with A/C, too. But, I'm like Grady posted above. I seem to remember only my low speed coming on with the A/C. So which is right?


He said that he NEVER has power to either side of the EDF fuse .... that doesn't sound right .... but I may be wrong. The signal goes through the relay control before getting to the CCRM .... so that fuse should see power, right?