Electric Fans on 2002 Silverado

[Hoho]

Hey everyone. I put Dorman LS1 replacement fans on my 2002 Silverado with a Blackbear performance harness. The fans work through pin 42 on pcm and the green wire splices into the AC wire. My concern is that they never turn on HIGH if the AC is NOT on. Coolant temp gets up to 205 degrees at idle and in traffic. Is this just what I get with this or is there a way to turn them on high? I would like to keep temps down even with AC off.

I'll attach my tune but here's a layout of the settings.

2 Fans
Fan 1 On: 188
Fan 1 off: 184
enable speed: 0
disable speed :45

fan 2 on: 192
fan 2 off: 190

ac pressure on: 0
ac pressure off: 500


I've tried modifying these slightly, but they just won't turn on Full blast unless the AC is on. Thanks for any help! (NOTE: tune is in beta)

[Google]

2nd fan or high is on the rec door pin in the pcm. pin 42 is for one relay only.

[Bill@HPTuners]

pretty sure you need to set the fan recirc to Fan #2 in this application

[Hoho]

I'm not very knowledgeable on this stuff so please excuse me.

To the first response: Does this mean I need to rewire my harness?

To the second: I don't seem to have this option in my tune. I'm checking 'advanced' view if that matters.

[Google]

Blue
pin 42 DK GRN 335 Low Speed Cooling Fan Relay Control


Red
pin 33 DK BLU 473 High Speed Cooling Fan Relay Control or recirculation door control

[Google]

If you click on the A/C Tab you will see the fan rec. door option

[Hoho]

I don't have the Recirc Option in VCM Editor. I've also run into debates about whether the 2002's have the option of using pin 33. The it only has 2 wires, a blue (which I put into pin 42) and a green (for the AC). Will I need to splice into the wire that goes into pin 33?

[Bill@HPTuners]

Hoho you need to contact support for the newest beta which adds this table & a few others. This table was added for guys just like you doing electric fan swaps into vehicles that never had one in stock form.

[Hoho]

Thanks. I just requested it, so I'll see how it works out.

[Hoho]

Ok. So the AC recirculation option is in the new Beta, but now I guess I will need to convert the normal green wire that spliced into the AC signal, and connect that to pin 33 on the pcm. Is that about right? Where can I get the connector to do that?

[Hoho]

NOW NOTHING WORKS! the only difference was that i used beta and now they don't come on low speed either. did the programmers mess this up? I need this to work now. I even put the tune i've been using and it no longer works.

[Hoho]

I hate to jump to a conclusion like that, but I just don't see anything else. I'll keep working with it, but please let me know if anyone sees this somewhere else.

[MikeGyver]

Doesn't the green wire for the A/C clutch provide positive voltage, and pin 33 grounds the signal? If so, you just need to change that relay so the other side of its coil has a hot going to it. Or you might need to change everything because you have three relays, do you not? Post your wiring diagram.

[Hoho]

I do have 3 relays. I do not have a wiring diagram because I bought the harness. The green wire does tap into the AC clutch signal and grabs power for 1 fan. The other wire ( blue) goes to pin 42 to be controlled by the computer. Until recently, both fans would come on low when coolant was at 190 or similar, and 1 fan would come on high with the ac on. After using the new beta to try and get functionality of fan # 2, they do not come on at all. But the 1 fan will still come on high if I put the AC on. So I think pin 42 is no longer responsive. I didn't change the wiring or anything like that. Either it was a fluke (I thought they were on before but they never worked to begin with), or something I did made them stop working.

[MikeGyver]

... or something I did made them stop working.

It is because you are trying to power the positive side of a relay's coil by using the computer's pin 33 to ground it. That won't work. Is the harness designed to use the A/C clutch signal, or is it designed to use the pin 33?
As to your original question, I think you should ask Blackbear if the harness was operating the fans as designed.

[Hoho]

It's not designed to use pin 33; it uses the AC signal. I was just trying to see if there was a way to get high speed without using the AC. I was only getting slow speed if the AC was off.

[MikeGyver]

Mine runs like you described, I wired it myself from schematics I found on Performancetrucks.net. It sounds like they are wired the same, I have three relays and it uses the A/C clutch wire, too. It maintains temperature though, because I have two sixteen-inch fans.

[Hoho]

It was doing alright before they stopped working. What kind of temperatures were you seeing? They don't come on low now either. Does AC pressure setting matter on these trucks? I just can't seem to get them to come on anymore.

[MikeGyver]

A/C pressure does not work. I'm sorry, for some reason I thought you did change and use pin 33.
I am not sure, but I don't think Beta has anything to do with your non-operation. It sounds like one of the relays might have took a crap.

[Hoho]

I've only had them about a month. Could they have really failed already?