Fan relay and sniper install

[clementine]

Hello FABO!

Ill list the components and you tell me how its wired.

Two speed derale (brown, black and grey wires) with two relays. (Red, orange, black, and yellow/green.)

Sniper EFI uses negative trigger to activate relay.

A/C wire currently wired to hi/low pressure switch.

Orange wire marked "electric fan" from 30 amp at bulkhead.

Relay black to efi trigger....ok... then what?? Does the green get spliced into the compressor that already has the hi/lo switch wired to it? Does the relay yellow and red get together with the orange "electric fan" that comes from bulkhead fused (30 amp)? Then relay orange out to fan?

Thanks FABO!

 

[67Dart273]

A few things

No idea what they are doing with the green the so called "diagram" is contradictory
85 and 86 are the relay coil and the OFTEN MATTER because many? most? relays have supression diodes in them. So connect the relay 86 direct to fused power and the 85, (ground) side of the coil should go to your EFI trigger. BUT CHECK THIS FIRST before you connect it. Try it by manually grounding the black to make sure the relay triggers and works, and PUT YOUR multimeter in series to measure coil current draw. And, "just to just to JUST TO" be safe, add a supression diode across the black to ground. You want it to "not conduct so you want the banded end at the relay and the opposite end ground

EDIT The diagram MAY BE incorrect if the relays have internal diodes. IT MAY BE that power should go to 86 SO CHECK IT. If you reverse 85 and 86 and IF there is an internal diode YOU WILL blow up either the internal diode OR THE EFI OR BOTH

CHECK THE RELAY TERMINAL NUMBERS BY THE DIAGRAM BELOW AND BY THE CONNECTOR COLORS WHICH MAY BE WRONG

 

[67Dart273]

There seems to be disagreement with how diode is connected, but they seem to be you need to connect coil PLUS power to 86 and 85 (in this case) goes to your EFI ground switch

THE BELOW RELAY seems to be drawn incorrectly IF THIS RELAY(s) has internal diode(s)

 

[Syleng1]

I believe the diode (which needs to be protected) is used to prevent spike back every time the compressor cycles. 80’s and early 90’s GM cars had them. Every time the compressor shut off the spike would do something to the computer and really mess them up and keep the compressor engaged. The diode was so damaged that gm built a fuse like diode so it could be changed easier to solve warranty costs. It’s been a long time since I worked on those BUT they are needed. In this case it may keep the relay from what I will call fluttering. Flashing on and off.

remember why the computer is connected to the relay(s) so it knows when to raise the idle to compensate for low rpm idle ac clutch engagement.

 

[67Dart273]

The relay COIL diodes are to protect the switching transistors in the EFI You are right about the compressor, but that diode needs to be across the relay CONTACTS

However, again, from the information posted, I cannot tell WTF they are doing tying the compressor to the fans "as shown"

 

[67Dart273]

Clem can you post a link to wherever you got the fan instructions? The tie-in of the green wiring is ????

 

[clementine]

roger wilco tomorrow. just got home from an epic evening of ping pong. I did have a guy from Derale confusing me earlier and he said the red and yellow go together and the green is attached to the compressor. I have a feeling that the compressor does not need two things triggering it. It is already attached to the hi/lo pressure switch and wonder if I were to use the EFI to trigger it, where would that hi/lo wire go? I appreciate the help I got some instructions in the fan box (black n white) and the color ones in the relay box. Ill get more on that manana.

Thanks fellas!

 

[AUSA66]

I would leave the green wire off relay 1 & Relay 2 black relay switch wire connect to Holley Sniper see below

10 Pin Connector – Mating Harness PN 558-491, 8 wires are populated. This connector contains: Pin Color Labeled Name Function A Orange Input #1 (-) Optional - Connect to a ground triggered A/C relay B Yellow Input #2 (-) Optional - Connect to a programmable ground input C Light Blue Output #1 (-) Optional – Connect to Fan #1 relay ground trigger D Light Green Output #2 (-) Optional – Connect to Fan #2 relay ground trigger
Yellow connect to a ground triggered relay if you cannot find connect a spare relay coil across the positive & negative clutch wire on the compressor then connect 87 to ground & 30 to yellow sniper A/C trigger wire so when you turn on the Air relay will close & connect Yellow Sniper wire to ground

 

[clementine]

I would leave the green wire off relay 1 & Relay 2 black relay switch wire connect to Holley Sniper see below

10 Pin Connector – Mating Harness PN 558-491, 8 wires are populated. This connector contains: Pin Color Labeled Name Function A Orange Input #1 (-) Optional - Connect to a ground triggered A/C relay B Yellow Input #2 (-) Optional - Connect to a programmable ground input C Light Blue Output #1 (-) Optional – Connect to Fan #1 relay ground trigger D Light Green Output #2 (-) Optional – Connect to Fan #2 relay ground trigger
Yellow connect to a ground triggered relay if you cannot find connect a spare relay coil across the positive & negative clutch wire on the compressor then connect 87 to ground & 30 to yellow sniper A/C trigger wire so when you turn on the Air relay will close & connect Yellow Sniper wire to ground

Ill re read this one in the morning. Im pretty bad at this stuff and to add to the confusion ....the relay pack from derale does not have numbers on it.

 

[AUSA66]

The numbers will be on the relay itself next to the pin.
Do Not !! connect any positive wires to the Sniper fan control wires if it does not blow the fuse it will damage the control module .

 

[70dart340]

Clementine, I have an O'scope if it'll help. I need to get your heads to you, too. Text me if we can do it this weekend.

 

[dodgy]

Didn't read all, but the green wire is an over ride so when your ac compressor is switched on your fans come on with it no matter what temp your at and the diode is there to stop your ac compressor coping any back feed and turning on with fans.

 

[clementine]

Ok. On this relay (i found the numbers!!)
30-red 14 ga
87- orange 12 ga
86-black 16 ga
85-green/yellow 16 ga and the green has inline diode
87 has nothing on it. Although i have the ability to put something there. This is the diagram from Derale for relays. It does not take into account that i am triggering it with a ground interrupt. What @AUSA66 said makes sense.....well kinda.

The screenshot pic of fans is from dude at Holley tech

Sorry, I'm not getting this right away.

 

[clementine]

Ok. So i think I'm closer here ..
Red to power from fuse box 30 amp.

Orange to fan (inline fuse?)

Black to efi

The yellow or green diode to compressor, but need to omit one of them. The hi/lo switch will trigger the yellow/green to turn on fans. I guess ill use the one will a diode (green).

I think that covers all the criteria as @AUSA66 was saying to relay the compressor circuit but i believe the hi/lo switch takes care of that.

Thanks FABO! The gears are starting to get warm.

 

[67Dart273]

You need to stop with the colors and talk in relay pin numbers. And you need to make CERTAIN this WORKS before you hook it to the EFI

HERE IS HOW a relay with an internal spike diode works, and how to avoid blowing it up

Even "I" have trouble because the internet is all over the place with published spike / flyback diode orientation/ polarity. You MUST test what you have to be sure it is right

In the diagram I posted--which I believe to be correct.......

The orientation of this diode dictates that + power be applied to pin 86, and ground side (EFI END) MUST BE 85. This connection cases the diode NOT to conduct. IF you were to wire this the other direction, the diode would act as a DIRECT SHORT and draw excessive current, blowing up whatever is weakest---a fuse, the EFI, or the diode itself.

 

[clementine]

Copy that. @67Dart273. I am going to swap out the hi pressure switch with a trinary unit and run from there to 86. Ill run 85 to EFI. Ill run 30 amp fused from dash to 30 and 87 to fan unit. I will research if I should utilize the diode wire or the non diode wire to the EFI out of 85. By running the trinary switch I will not be splicing and dicing my signal from the pressure switch (switched 12 v) Ultimately as to not fry EFI I will not make that connection until I have system powered up to verify it IS NOT getting more than it needs...I think it can only handle 2 amps...not sure what that is in voltage yet....baby steps here now.

Thank you fellas.....we gettin there, just aint there yet-Rat Rod Bob

 

[clementine]

Update: I have figured that I am going to run two relays for the fan. One for each speed. 30 and 87 will be the big power guys and 86 keyed power and 85 will go to the efi for ground interrupt. I am planning on leaving the pressure switch for the ac alone for now to see if it activates the fan either through its own circuits or that the engine reaches temp and turns on the fan through the efi. that temp I can set through the wizard during setup. If I am not happy with this scenario, I will add more relays to trigger the fan through the pressure switch. Does this sound like Im on the right track? I will bench test this scenario before hooking up to efi to make sure I am not backloading the efi with power. (yes, I said backloading)

Thank you,
Sparky

 

[67Dart273]

If you are triggering these off the same output off the EFI you need to check the specs for the current they can handle, against what the relay coils draw

As I said before, CHECK these by manually grounding the trigger BEFORE you hook to the EFI. This will make absolutely certain you don't have a relay with a reversed diode. It would not be a bad idea to measure the trigger current as well

Simply put your multimeter from the relay trigger wire to ground in current mode

Sorry I can't be more specific help but with the info I'm seeing and that color coded plug, I am unable to justify the colors to the relay terminals, plus, LOL "I ain't there."

 

[70dart340]

Check your vintage air instructions, too, Brother. Many modern systems, including my '08 Nissan Frontier, have a separate fan and switch that is controlled by the head pressure of the condenser.