Cam's FJ60 Gets a Heart Transplant

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I have 12v or more when I connect Tach output from ECU to ground.

I do not have a voltage reading at the AC plug to the compressor.

Also, my tach does show anything. Shouldn't it still show something, but be off?
 
I jumpered the compressor clutch manually, thinking I didn't have enough refrigerant for it to run (although that worked last time).

It does work that way, and I was able to charge it. However, that wasn't the problem.

I'm still not getting +12v at my old AC clutch wire.
 
Gauge readings, outside temps 70-75 degrees.

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Vent temp

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We've determined that the AC isn't working because Rob wasn't present. Just like the fuel pump mystery. There's no reason it shouldn't work like I have it. I've read every thread pertaining to AC in swapped trucks and I am following the recipe exactly. I probably have a bad connection that I've since taped up.

I've been DD'ing it ever since getting the exhaust done. I've got about 300 miles on it so far with no issues. I love it. I drove the Lexus (car) yesterday, and while I miss the power windows and all that stuff, it just wasn't as fun to drive.

Whatever the guy did to my transmission tune, I love it. You press the gas from a start and the power is almost as direct as driving a stick. It shifts quickly, but smoothly. Much more of an immediate response than the Lexus. (Not nearly as refined, of course.) I think he said he bumped up the pressure a little, but not enough to affect longevity.

I'll get some mpgs in a day or two. It's definitely not dropping as fast as before.

I've changed my mind on the OBD/ iphone app thing. Since it uses wifi, the phone thinks it can use that as an internet connection, so sometimes you have to juggle turning it on and off. Also, when I pull up at home or work, it will switch wifi's without warning which drops the signal. If apple would do Bluetooth, it would be better. I think I'm back on wanting a scanguage.
 
A/C working now or no? Magically getting 40F at the vent.. :)
 
No, it's not working unless I hot wire the compressor clutch.

I pulled apart my connections tonight but couldn't find anything wrong.

Does your tach register at all? Should mine, if I connect the ECU tach output to the coil - ?
 
yes...my tach works.... it revs and all of that..just way off from reality (based on I-6 Tach configuration vs V8 signal)... yes yours should work with no mods beyond the a/c business

tach signal feeds the wire from the neg side of the coil (this is on my 5.7 and on another guys 5.3) so should work for you without issue. then you use the factory a/c hot wire that feed the old compressor to trigger a relay that feeds teh new compressor 12 volts at a/c on so compressor engages.

Get the freon fully charged and get the idle up around 800RPM to a 1,000RPM to see what happens. Mine would not engage until freon almost fully charged and sometimes driving it will not engage until rpm increases.

You can adjust a/c compressor engagement at the A/C amp under the dash...(blue knob)...

Have you got it fully charged and let the compressor run to ensure you got cold air...is that the pic?
 
you should have a functioning tach.... check wiring for screw ups... that tach feed into the neg wire drives the tach...which also tells the ac amp the engine is running and a/c can engage...(based on what I recall)... anyway you got to have a tach signal to make it work on a gas engine...see if you have any loose connections and have the right wires involved.
 
It is fully charged.

My tach isn't reading at all. How can I tell if my "tach" signal is really a tach signal?

Because the coil neg side of things (tach and AC) worked just fine before the swap, I'm thinking the odds are that it still works.

Which makes me question the tach signal. Can I fake one somehow?
 
Not sure on how you would fake the tach signal...I know some of the engines across the different years of 5.7 fuel injection have a variation on the signal they generate. I think the GM shop manual may define the specs on the tach signal for that year engine. Yeah if the wiring is correct, then it would sound logical to question the tach signal you are using, or there may be some flaw in it.

Not sure how to test for that but I'm sure you probally could test the tach lead to see what is going on..(to see if its live or working)...may need to trace the wire back to the ECM plug to make sure its not loose or something.

In the old days you could piggyback off the distributor...but....

I'm thinking that signal has to come off your engine harness or there might be a wire you could tap on the ECM harness (just have to see which one)...

I don't have a 5.3...just make sure the GM compressor does not have any other pressure sensors or anything else on the compressor side that controls the engagement of the clutch..I assume thats ok since it did work when you hot wired it..but just wondering.
 
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I did some digging. It sounds like I have several options.

One is to swap with an AC amp from a 62, which supposedly is triggered by a 12v ignition signal vs a tach signal. This will keep it fully functional, except the clutch will be engaged any times the ignition is on, even while starting, adding drag to the starter. (I could wire to cig outlet, which is off while starting.)

Another is this tach signal generator thingy. https://forum.ih8mud.com/threads/a-c-tach-signal-mod-for-v8-conversions.628690/ It sounds like he had the same issue - the tach signal wasn't strong enough or whatever enough to trigger the 60's AC system.
"... I wired up the A/C circuit like I thought it was supposed to be wired. One of the signal wires coming out of the Vortec PCM is the tach signal wire. I thought I would just wire up this tach signal wire directly to my A/C amplifier tach signal wire and all would be well. Well, it doesn't work. (Since I don't have an oscilloscope, I can only assume that the PCM generated tach signal isn't strong enough for the FJ60 a/c amplifier to pick it up)..."​

There are other methods that involve opening up the under dash bits to install a temperature switch, but I don't want to get into all of that.

I want it to be as little of a 'hack" as possible. I've got some more digging to do, but the 62 AC amp might be the cleanest thing to do.

Before I get into all of that... how can I test my original system downstream of the coil (-) wire? I know it worked before, because when I first hooked up my TBI, I didn't have a tach or AC. Reconnecting the coil (-) made them functional.
 
running a diesel a/c amp might be an option...too, but obtaining that might be $$ and hard to source.

I don't have more advice but to dig around on the board and through the shop manual, because I've not looked into any further myself. Seems like your truck should be no different than mine...
 
My A/C clutch is wired to the key. Starts just fine with it engaged.
Maybe it would add enough drag to make a difference when it is cold, but I don't have A/C on if it's cold.

It might not add much drag when it first starts spinning. Spins slow and no pressure built up yet.

JW
 
Elbert said:
running a diesel a/c amp might be an option...too, but obtaining that might be $$ and hard to source.

I don't have more advice but to dig around on the board and through the shop manual, because I've not looked into any further myself. Seems like your truck should be no different than mine...
Click to expand...

From internet digging outside of 'mud it sounds like the later ECMs put out a weaker signal, and this is not an uncommon problem with engine swaps in general with getting the tach to work. Sometimes the signal needs a boost with a pull up resistor. It just so happens that I also need it to make the AC work.

nuclearbeef said:
My A/C clutch is wired to the key. Starts just fine with it engaged.
Maybe it would add enough drag to make a difference when it is cold, but I don't have A/C on if it's cold.

It might not add much drag when it first starts spinning. Spins slow and no pressure built up yet.

JW
Click to expand...

Yeah, it'll start no problem with the clutch engaged. Do you have yours wired into any kind of temp controller to keep the coils from icing?


Can I just run it nonstop until I get this figured out? Will I have any bad side effects other than coil icing?
 
wngrog said:
You are getting boring. More noise. Less engineer talk.
Click to expand...


To change the subject... how much bigger than the fan does the hole in the shroud need to be?
 
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