to anyone running a truck ac bracket

[cjohnson6772]

I have notched my compressor bracket with no issies, but how do you connect the red plug?!?!?!?
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[clinebarger]

Thats the High Pressure cut-out switch, Not used on swaps.

You can run a Trinary on the a High side line..... http://www.oldairproducts.com/catalo...ch-p-2754.html

Use a Relay for the fan, The diagram doesnt show one but is necessary.

The Trinary switch is a 3 function switch. It Protects the system from excessive high or low system pressures plus it will automatically operate electric radiator or condenser fans as needed for maximum sytem performance.

Trinary Safety Switch Pressures:
LOW is OFF @ 28PSIG - ON @ 29PSIG
HIGH is OFF @ 454PSIG - ON @ 369PSIG
FAN - is ON @ 227PSIG - OFF @ 185 PSIG

[cjohnson6772]

Originally Posted by clinebarger

Thats the High Pressure cut-out switch, Not used on swaps.

You can run a Trinary on the a High side line..... http://www.oldairproducts.com/catalo...ch-p-2754.html

Use a Relay for the fan, The diagram doesnt show one but is necessary.

The Trinary switch is a 3 function switch. It Protects the system from excessive high or low system pressures plus it will automatically operate electric radiator or condenser fans as needed for maximum sytem performance.

Trinary Safety Switch Pressures:
LOW is OFF @ 28PSIG - ON @ 29PSIG
HIGH is OFF @ 454PSIG - ON @ 369PSIG
FAN - is ON @ 227PSIG - OFF @ 185 PSIG

Awesome! That means my A/C bracket should work with the notch I'm pretty sure the switch in my current A/C set up (manual fan/TPI/Sanden 508) is a binary switch. So with a trinary switch, will the PCM still control the compressor and fans? If I understand your post correctly, with PCM controlled F-Body fans and PCM controlled compressor the fans would run when the PCM deemed necessary due to the coolant temp OR when the trinary switch deemed necessary for better A/C performance. Is that correct?

[cjohnson6772]

Originally Posted by cjohnson6772

Awesome! That means my A/C bracket should work with the notch I'm pretty sure the switch in my current A/C set up (manual fan/TPI/Sanden 508) is a binary switch. So with a trinary switch, will the PCM still control the compressor and fans? If I understand your post correctly, with PCM controlled F-Body fans and PCM controlled compressor the fans would run when the PCM deemed necessary due to the coolant temp OR when the trinary switch deemed necessary for better A/C performance. Is that correct?

Bump for clarification please. Also: I have my binary switch installed right after the bottom of the condenser. Is this location ok?

[ChevyCruizer]

Im not Clinebarger, but I will try to help...

yes

In your current setup if the PCM is controlling the fans for coolant and you add this switch then either or both will cycle the fans. The PCM will only turn on and off with coolant temp and the trinary will cycle on and off as necessary for the AC based on the pressures previously posted. Just make sure you are tapping the trinary into the correct relay circuit for the cooling fan (should already be there if the PCM is controlling the fans)

Originally Posted by cjohnson6772

Awesome! That means my A/C bracket should work with the notch I'm pretty sure the switch in my current A/C set up (manual fan/TPI/Sanden 508) is a binary switch. So with a trinary switch, will the PCM still control the compressor and fans? If I understand your post correctly, with PCM controlled F-Body fans and PCM controlled compressor the fans would run when the PCM deemed necessary due to the coolant temp OR when the trinary switch deemed necessary for better A/C performance. Is that correct?

[cjohnson6772]

Originally Posted by ChevyCruizer

Im not Clinebarger, but I will try to help...

yes

In your current setup if the PCM is controlling the fans for coolant and you add this switch then either or both will cycle the fans. The PCM will only turn on and off with coolant temp and the trinary will cycle on and off as necessary for the AC based on the pressures previously posted. Just make sure you are tapping the trinary into the correct relay circuit for the cooling fan (should already be there if the PCM is controlling the fans)

Thanks for the info. Is a trinary switch worth the extra money and effort if I have a binary switch already? I don't think I understand why the fans need to turn based on the compressor pressure...I mean they are already temp controlled? What is the added benefit of a trinary switch in this scenario? Sorry if this is a dense question :\

[1970 C10 MJW]

i dont know much about this, but I would like to know exactly how that work, sense I plan on doing A/C at some point

[Clyde65]

I have old air on my truck with the LS swap. Clinebarger did my AC stuff for me, since I havent a clue. My Trinary switch is right at the condenser, I dont think it matters as ling as it is on the high side, however, when I installed my Old Air kit, they said put it near the condenser. PM Clinebarger if you have further ?'s

[faribran]

thanks guys, this is very helpful info...

[Daaaanz67]

This is good info getting ready to do a/c also. Can someone post a wiring schematic for the trinary to the fan that's already controlled by PCM. Maybe Cline can chime back in on this thanks.
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[clinebarger]

Originally Posted by cjohnson6772

Thanks for the info. Is a trinary switch worth the extra money and effort if I have a binary switch already? I don't think I understand why the fans need to turn based on the compressor pressure...I mean they are already temp controlled? What is the added benefit of a trinary switch in this scenario? Sorry if this is a dense question :\

Without a mechanical fan it's Mandatory in my opinion! At low speeds/stopped you will need airflow across the condenser if Head Pressure gets to high (<250 psi)....High Head pressure will.....Decrease A/C performance, Blow lines, Break belts, Break the compressor, Break the tensioner & Smoke compressor clutches.

Originally Posted by Daaaanz67

This is good info getting ready to do a/c also. Can someone post a wiring schematic for the trinary to the fan that's already controlled by PCM. Maybe Cline can chime back in on this thanks.
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Do Not wire the Trinary to the PCM controlled relays, It will set codes & the PCM will freak out & turn the fans on at all times....Here's a diagram on the Correct way to wire it....

[chevyman70]

Originally Posted by clinebarger

Without a mechanical fan it's Mandatory in my opinion! At low speeds/stopped you will need airflow across the condenser if Head Pressure gets to high (<250 psi)....High Head pressure will.....Decrease A/C performance, Blow lines, Break belts, Break the compressor, Break the tensioner & Smoke compressor clutches.




Do Not wire the Trinary to the PCM controlled relays, It will set codes & the PCM will freak out & turn the fans on at all times....Here's a diagram on the Correct way to wire it....

I have a mechanical fan on my swap. Will that be sufficient to cool condensor and keeping the engine cool?

[clinebarger]

Originally Posted by cjohnson6772

It t was then that he realized that the condenser also needs airflow and not just the radiator.....doh

So to add to the diagram: pin 87 of the pcm relay and pin 87 of the trinary switch relay will both be hooked to the hot wire on the fan?

In the interest of pursuing alternatives: could I not just wire my a/c signal on wire (clutch hot wire) to pin 86 of the additional fan relay and forgo a trinary. I believe this would turn the fans on any time the clutch was on.

Since the PCM gets a A/C power signal and controls the clutch....could the fans not be programmed to turn on with the clutch with no additional mods?

Thanks for all the advise and patience. I'm just trying to fully understand my options.

You can wire it to run anytime the A/C is on, But the fan Does Not need to run a highway speeds & will wear the fan motor out prematurely.

Originally Posted by chevyman70

I have a mechanical fan on my swap. Will that be sufficient to cool condensor and keeping the engine cool?

If your running a 134a parallel flow condenser, And the shroud fits correctly around the fan....Yes, It should be fine.

If you got a R-12 "tube & fin" condenser or the shroud doesn't fit the fan right.....Your going to have problems.

As a matter of fact I run a Mechanical fan on my Burb.

[chevyman70]

Originally Posted by clinebarger

You can wire it to run anytime the A/C is on, But the fan Does Not need to run a highway speeds & will wear the fan motor out prematurely.



If your running a 134a parallel flow condenser, And the shroud fits correctly around the fan....Yes, It should be fine.

If you got a R-12 "tube & fin" condenser or the shroud doesn't fit the fan right.....Your going to have problems.

As a matter of fact I run a Mechanical fan on my Burb.

The condenser I ordered is a parallel flow, and my fan fits like a glove on my shroud, tight fit. So, Ill try it with the mechanical first, if I have cooling issues, then i'll change over to a pair of electric fans. Thanks for the tip!

[cjohnson6772]

Originally Posted by clinebarger

You can wire it to run anytime the A/C is on, But the fan Does Not need to run a highway speeds & will wear the fan motor out prematurely.

Looks like a trinary switch is gonna have to fit the bill. I just hated the thoughts of adding wires and relays if there was any chance I could just let the PCM logic handle it :\ I guess you shoulda told me like my dad always did "You have two options: you can do it my way now or you can try it your way and then do it mine later"

As an aside: Will this compressor block work on my compressor? The links all say R4/A6 rear mount and the pad face looks to be perfectly flat. My compressor is off a 2001 LQ4 and I thought the original pad face would have a slight offset. Thanks again everyone.

[bigoilman]

Originally Posted by clinebarger

Without a mechanical fan it's Mandatory in my opinion! At low speeds/stopped you will need airflow across the condenser if Head Pressure gets to high (<250 psi)....High Head pressure will.....Decrease A/C performance, Blow lines, Break belts, Break the compressor, Break the tensioner & Smoke compressor clutches.




Do Not wire the Trinary to the PCM controlled relays, It will set codes & the PCM will freak out & turn the fans on at all times....Here's a diagram on the Correct way to wire it....

Wiring my VA last night and had a question about this post. My harness has the factory plug with one green and one black wire going to the compressor. Do I disconnect that plug, splice into the green wire and ground the black wire?

Thanks.

[clinebarger]

Originally Posted by bigoilman

Wiring my VA last night and had a question about this post. My harness has the factory plug with one green and one black wire going to the compressor. Do I disconnect that plug, splice into the green wire and ground the black wire?

Thanks.

The Black wire should already be grounded. Yes, the Green wire can be cut....Then run the Vintage Air Comp. Clutch wire to it from the Binary/Trinary.

[cjohnson6772]

It t was then that he realized that the condenser also needs airflow and not just the radiator.....doh

So to add to the diagram: pin 87 of the pcm relay and pin 87 of the trinary switch relay will both be hooked to the hot wire on the fan?

In the interest of pursuing alternatives: could I not just wire my a/c signal on wire (clutch hot wire) to pin 86 of the additional fan relay and forgo a trinary. I believe this would turn the fans on any time the clutch was on.

Since the PCM gets a A/C power signal and controls the clutch....could the fans not be programmed to turn on with the clutch with no additional mods?

Thanks for all the advise and patience. I'm just trying to fully understand my options.

[chevydog66]

Subscribed. But I'm not running electric fans. I am using the stock 6.0 fan with the stock 72 GMC fan shroud.

[Gordonr1973]

Great thread! Subscribed.

[cjohnson6772]

Just came back from getting my compressor charged and I've got an issue. I've got my compressor clutch wired in with the trinary switch inline, but I'm not getting a signal on either side of the trinary switch. I've check and the A/C relay is not getting grounded by the PCM on pin C2-43. I suspect the culprit is the missing high pressure sensor supposed to be on pins C2-14, C2-57, & C1-45. I have a plug in my harness for the sensor, but there is no way to hook it up because of my engine stands. Is there a way to "tune this out" or "sppof" the PCM into ignoring the sensor? It doesn't look like a switch that I could just bypass of a potentiometer that I could just use resistors to get around, so I'm lost. As always thanks in advance for the help.

[clinebarger]

Originally Posted by cjohnson6772

Just came back from getting my compressor charged and I've got an issue. I've got my compressor clutch wired in with the trinary switch inline, but I'm not getting a signal on either side of the trinary switch. I've check and the A/C relay is not getting grounded by the PCM on pin C2-43. I suspect the culprit is the missing high pressure sensor supposed to be on pins C2-14, C2-57, & C1-45. I have a plug in my harness for the sensor, but there is no way to hook it up because of my engine stands. Is there a way to "tune this out" or "sppof" the PCM into ignoring the sensor? It doesn't look like a switch that I could just bypass of a potentiometer that I could just use resistors to get around, so I'm lost. As always thanks in advance for the help.

The original switch on the compressor was not a pressure sensor, It was a Cut-Out switch....Pressure too high would interrupt the A/C request signal. 99-02 trucks are all wired this way because of the mechanical cooling fan.

Cars (4th gen F-bodies) do have a pressure sensor mounted on the Liquid Line. Using this the PCM was able to control head pressure with the cooling fans.

I'm guessing your running an F-body OS/segment swap to run electric fans. This will prevent ECM controlled compressor operation if no pressure reading. Also....If the harness is early truck....There is not a 3-pin pressure sensor plug, Only a 2-pin high pressure cut-out switch plug.

This is my opinion.....Run the compressor control wire straight to the aftermarket Trinary then to the compressor & bypass the ECM all together.

[ls1nova71]

That schematic is not for a truck. It looks more like an F body. I would do as Cline suggested and bypass the PCM control all together, or wire it like a truck. Having it controlled by the PCM doesn't really get you much. Have the fans come on with the trinary switch and leave the computer out of it, it will be easier in the long run.
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[Clyde65]

Clinebarger did my rewire and Ac repair, what a mess I had. Now my truck rolls down the road with Ac on or off at 190 degrees in our lovely Texas heat. He knows what he is talking about, he does these swaps everyday.
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[cjohnson6772]

Great info guys. I had no idea that there was such a difference between cars and trucks as far as a/c working. I'm beginning to really regret my harness purchase. The schematic I have came with my harness. But I told him explicitly it was for a DBC Truck and 4L80e. I get back a harness for 60e. Easy fix but nonetheless......OK off my rant. I dug around through all the pin outs I could find and LT1swap.com after Cline's post and found the truck schematic which just shows the switch inline like he said. I've emailed my tuner to see about the segment swap. I know we flashed two different OS's but I'm almost certain we went back to truck OS. And enabled the second fan just by changing the pin from the a/c recirc door to fan 2. I will wait for a response back and in the meantime roll under the truck to see if my harness connector is 2 or 3 pin. Hopefully I can just jumper that connector and be done with it. Otherwise I will bypass the PCM altogether. Thanks as always. You two are gentlemen and learned scholars.
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