Dual Fans - Vintage Air - ProFlo-4 ECU

[C10forDad]

I have seen lots of posts out there about LS swaps and VA trinary switch wiring, but surprisingly none with the ProFlo-4 setup.

I am attaching a PDF of a wiring diagram that I believe is correct.

I am looking for some validation and if it isn't right, some clarification of what should be done.

This is what I believe to be correct so far...

1. ProFlow-4 ECU has the following
   • 2 Ground activated output triggers from its ECU that get wired to their specific Fan Relay
   • 1 Key on 12V+ that gets connected to both of the Fan Relays
2. The Trinary Switch has the following
   • 1 Wire connected to the Compressor
   • 1 Wire connected to the Vintage Air Compressor Relay
   • 1 Ground
   • 1 Wire that gets connected to only the Fan #2 Relay

I did find that the ProFo-4 ground activated output triggers from its ECU can be programmed to activate at different temperatures. This makes sense since there are two separate wires.

The logic that I was trying to wrap my head around is that the Trinary Switch is asking for both fans, but really only needs to request the #2 fan. This logic is sound for these reasons...

• Both fans do not need to be on if the engine is cold while the AC is on
• If the engine is at operating temperature, the AC is on, and the head pressure is not high, then Fan #1 will already be on.

[PbFut]

You are attempting to run two relays with 3 control wires and the 2 ecu wires may not like a direct ground backfeed if the trinary switch triggers. You can isolate using additional relays or diodes if you trust them. Be sure the ecu gets clean power and does not receive line noise from the fans. Think of the ecu like wiring up a super high end stereo in a ultra quiet luxury EV. Like the stereo, the ecu needs consistant clean power and fans don't play well with clean power supply.

[Richard]

Agree with the previous post. Also note when running two fans it is very inefficient to run only one fan unless there is a divider between them. If an open shroud between the two, a large amount of air from under hood will just be recycled instead of being pulled trough radiator when only one fan is running. Air will follow the path of least resistance which is through the non running fan. Reducing speed on both fans at first call is a better option. Yes, running just one fan may work for some.

[C10forDad]

These are the fans that I'm using

[C10forDad]

The fans are grounded to the core support.
Both the ECUs have there own dedicated power and grounded inside the cab at different locations.
I didn't put in the wiring diagram, but both ECUs have their own relays built into their harnesses.

[Rickysnickers]

If you want, there's a forum Edelbrock has running, that's actually very active. One of the subgroups is the Pro Flo 4 and Pro Flo 4+. I might want to go there and check it out.

https://forums.edelbrock.com/

[PbFut]

Originally Posted by Richard

when running two fans it is very inefficient to run only one fan unless there is a divider between them. If an open shroud between the two, a large amount of air from under hood will just be recycled

Great comment. I learned something today.

[C10forDad]

Originally Posted by Rickysnickers

If you want, there's a forum Edelbrock has running, that's actually very active. One of the subgroups is the Pro Flo 4 and Pro Flo 4+. I might want to go there and check it out.

https://forums.edelbrock.com/

I have tried searching that forum in the past and came up empty.

Additionally, I absolutely drew the first diagram incorrectly and this should be correct now according to how Vintage Air shows it in their video.

[A1971Blazer]

I don't know if this will apply to the Pro-Flo system but at first I just wired the trinary switch together with one of the trigger wires on my factory PCM thinking that either one would be able to turn on fan 1.

The PCM didn't like that because if the fan was already on (grounded thru the trinary switch) the PCM would set a MIL code (relay ground fault).

I simply added an additional relay and separated the trinary ground trigger from the PCM ground trigger.

[PbFut]

The ecu needs clean travel paths. The fan trigger wires are internal electronic switched to ground. Only one relay coil is to be connected to the fan leads. The ecu can't handle anything else. Ignore the trinary switch. There should be a wire that needs +12v into the ecu when ac is on. Best if you can pull from compressor but could be tricky and need a relay if the compressor is switch on the negative side. If so, you will have to add a relay to turn the negative side swith to a +12v signal. Depending on ecu, there will be 1 2 or 3 fan triggers. Some only trigger fan 3 for ac. You can not cross or share relays. If you have 2 fans and 3 triggers, you need to get a dpdt relay for fan 3 and do some tricky wiring to keep all 3 ecu triggers isolated and control only 2 fan relays. I did on my system and works correctly. Also, the +12v side of the relay coils needs to go to battery. You don't want noise back feed into those 3 ecu trigger wires. The ECU is very susceptible to dirty power.

[C10forDad]

Originally Posted by PbFut

You can not cross or share relays.

Then why would Vintage Air have a video showing the fan relay being shared between the ground triggers from the temperature sensor and the trinary safety switch?

https://youtu.be/l604JCZx_ow?si=puAjJEm5XPCGkNq7

[PbFut]

That is NOT a wire setup that can be used for a ECU trigger fan relay. If you swap the temp switch for a ecu you risk a back feed because you have a path to direct ground at pin 86 via the trinary switch. Strongly suggest you understand relays and isolation requirements of your ecu. Do not blend old style wiring with modern ecu electronic switches. Very different animals and they react and behave very differently. The fan relay trigger can not share multipal grounding paths.

[C10forDad]

Originally Posted by PbFut

Strongly suggest you understand relays and isolation requirements of your ecu. Do not blend old style wiring with modern ecu electronic switches. Very different animals and they react and behave very differently.

Thank you for this input.
This is exactly what I needed to hear.

[weq92f]

Originally Posted by C10forDad

Thank you for this input.
This is exactly what I needed to hear.

.

FWIW and something you may consider here.

I wired my trinary switch to trigger a pusher fan mounted on outside of condenser. This took the A/C-related fan cycling out of the primary cooling fan system and applied the air flow directly where needed.

Prior to this, my ECU was activating fan #1 when it got 12v signal indicating A/C pump ON. That main fan #1 hits pretty hard when it activates and so the cycling was evident and IMO too often. The smaller fan installed on the condenser pulls less amps and seems to cycle happier while keeping vent temps acceptable.

Hth,

-Kevin

[A1971Blazer]

This diagram shows how I separated the trinary ground trigger from the PCM ground trigger to turn on the fan either by the trinary switch or the PCM as needed.

[C10forDad]

I think that I got it this time and am using 4 relays.
All of the trigger grounds are completely isolated and have their own relay. with a fourth relay that powers the second fan.

Relay #1 ECU Temp #1 triggers Fan #1
Relay #2 ECU Temp #2 now triggers Relay #4 to power Fan #2
Relay #3 A/C High Pressure now triggers Relay #4 to power Fan #2

[PbFut]

Looks correct. You did not show the connection to the ecu from trinary/vintage air +12v to let the programing know there is an additional load of the compressor. Most efi systems have a sensor wire to look for +12v signal when the compressor is running. It triggers a tuning modification to adjust the IAC valve, timing, and RPM. Normally all configurable in the software. This allows compressor cycling with little to no noticable affect on engine idel.

[C10forDad]

Originally Posted by PbFut

Looks correct. You did not show the connection to the ecu from trinary/vintage air +12v to let the programing know there is an additional load of the compressor. Most efi systems have a sensor wire to look for +12v signal when the compressor is running. It triggers a tuning modification to adjust the IAC valve, timing, and RPM. Normally all configurable in the software. This allows compressor cycling with little to no noticable affect on engine idel.

Thanks!

The Vintage Air wiring harness from its ECU has its own relay that supplies a +12V signal to the black/green wire on trinary safety switch.

I could not find any information stating that the ProFlo-4 has the ability to sense the load the A/C compressor.
However, these systems do have the ability to learn and adapt to different loads quickly.

I am also using a Dakota Digital instrument cluster with a BIM so that all ECUs can work together and display accurately on the gauges.

Edit: I added to the diagram the following items

1. a fused distribution block
2. changed power supply to relays 2 and 3 that are only powering another relay
3. Vintage Air ECU
4. Vintage Air Compressor Relay to Trinary Safety Switch