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

[yellowstang1994]

HI guys,

I've read a lot on here that when you turn your A/C on max that your highspeed fan is supposed to come on. With my car being hotter than normal I thought my low spd wasn't working. So I finally got a different CCRM and started testing. A little confused I put my old one back in and tested it with a DMM. So at about 215* or so my low spd fan comes on. And a little over 230* my highspd fan comes on. However the whole reason for this post is, with my A/C on max the high spd fan never comes on, only the low spd (as in both pin 14 and 17 have voltage). Is this really that the low spd fan thats supposed to come on and everyone has been saying high spd? or is my car jacked up or something?

 

[HISSIN50]

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.

 

[yellowstang1994]

Hmm, this is very awkward then. I rechecked everything, and both pin 14 and 17 have voltage to them. My DMM says they're getting around 15v, although it is a peice of crap I can't get my friends fluke until later tonight. Either way the low speed fan is definatley coming on instead of the high. I checked the fan connector with the car on and max a/c on and like you said the top is grounded. At first I got voltage at the middle and nothing at the bottom, but then it switched on me and reversed. Do you have any ideas what this would indicate? I'm stumped...

Also, you were helping me with the EDF a few posts back when I started inquiring about this problem. Some of the stuff you were talking about kind of went over my head on the EDF but my EDF fuse never has any power on either post. Is it supposed to be like this? And could this be whats causing this? Also if it is of any help I did a KOEO test and a KOER test and both tests came out good, no problems.

Thanks for the help.

 

[final5-0]

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]

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.

 

[final5-0]

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.

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

 

[HISSIN50]

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.

 

[yellowstang1994]

Thanks Hissin,

I honestly don't know anymore. The EDF fuse isn't blowing, they are all good fuses I put in, and they stay that way. There is no power what so ever going to the fuse. I checked it with the car running many times, at different op. temps (if that even has anything to do with it). Anyway, I'm not going to worry about it too much right now. It's not the biggest deal in the world. But thanks for the help.

 

[HISSIN50]

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.

 

[SeventyMach1]

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?