A/C question

[FJKai]

So I finally hooked up the a/c after doing a sbc 400 engine conversion a year + ago and bam, no power at the line/clip under the hood. So the fan blower and the a/c indicator light all work and light up, but there's no power at the line under the hood. Luckily the a/c tech was cool and just rigged up an easy line to battery to power the comp. pump and filled her up. So now I got a/c that works sweet, just no power (unless I power it directly off the battery). I know that the comp. pump needs to go on and off so the system doesn't freeze up, so I'm kinda hoping to get it working right (instead of say a toggle switch fix). Any recommendations? I've checked the fuss which is fine. The thing worked fine before the engine conversion, and all we did is un-hook everything, so I can't understand the power line problem. Anyone? Is there a relay somewhere that could be bad? My luck would be somewhere under the dash that's hard to get to, but I don't know, so anyone have ideas or a similar problem and fix?

 

[rchalmers3]

So I finally hooked up the a/c after doing a sbc 400 engine conversion a year + ago and bam, no power at the line/clip under the hood. So the fan blower and the a/c indicator light all work and light up, but there's no power at the line under the hood. Luckily the a/c tech was cool and just rigged up an easy line to battery to power the comp. pump and filled her up. So now I got a/c that works sweet, just no power (unless I power it directly off the battery). I know that the comp. pump needs to go on and off so the system doesn't freeze up, so I'm kinda hoping to get it working right (instead of say a toggle switch fix). Any recommendations? I've checked the fuss which is fine. The thing worked fine before the engine conversion, and all we did is un-hook everything, so I can't understand the power line problem. Anyone? Is there a relay somewhere that could be bad? My luck would be somewhere under the dash that's hard to get to, but I don't know, so anyone have ideas or a similar problem and fix?

Hey! I'd go to the A/C fuse in the fuse block first! Then if it's good, go to the amplifier on the evaporator box and pin it out for power and grounds. You can jumper power there to bypass the temp cut off and verify the system will operate from the amplifier.

Rick

 

[kevinmrowland]

You're in luck, most of the AC stuff is easy to get to!
Anyway, your issue is probably that you no longer have the same pulse signal from the coil (tach signal) as a result of the engine conversion.
The 60 amp requires a go-no-go signal from the coil, if you got your OE tach to work, then you can splice the black line from the amp into the tach signal and be all set. Otherwise your best option will be to swap in a 62 amp that doesn't require that tach signal (almost a plug-n-play swap).
Check to make sure that you have power at the amp to start with, but then go this route.
It is late and I am tired at the moment so if you want more immediate info search my username and AC, I've talked about this issue a few times.
Or, ask any questions and I will check back tomorrow.

 

[rchalmers3]

Gee Zuss, I very recently dealt with this very same issue when I did a 2H conversion. How did I forget? Must be the nearly 50 years I have accumulated.....

I used a spare relay I had laying around and wired it through the thermistor cut off circuit on the amplifier to make a functioning system without repalcing the amplifier. I'll leave the same offer as Kevin: search my threads or post questions and I'll help ya in any way I can. If I can remember......

Rick

 

[kevinmrowland]

Did you use the relay to switch 12v to the coil signal wire? I've been wondering if the amp would operate if it just had a straight voltage run to that wire, since it is technically supposed to run off a pulse.
Keep in mind that the coil signal is supposed to operate not only as a low engine speed cut off, but also as a cut off during starting so the starter motor is not turning the AC pump in addition to the engine.

 

[FJKai]

Ah! Well with the conversion I didn't use the OEM rpm gauge, I took it out and used a small replacement one, so it sounds like my problem is along the lines that Kevin mentioned. This was the info. I was waiting to hear, I'll search it up and see what I get. Thanks a lot.

 

[kevinmrowland]

Copied over from PMs for everyone else's edification:

Hello. From the sounds of your response, it sounds like you got this a/c stuff down. I wanted to ask a bit more if you could. So as you may have read, I don't have the stock tach anymore, so I guess that's my problem. Where is my (60 series) amp at? I went to Spector's web site and they show a diagram of the a/c and amps, but I don't understand where is is on the vehicle. So does the 62 amp essentially plug into where the 60 amp goes, easy and simple? Any other mods I need to do or splicing or additional wiring? I apreciate your help, I'm totally stumped by this so far, your info has really helped.
-roger

Originally Posted by kevinmrowland
Hey Roger,
The tach is not the problem, but where the tach got the signal from is, your engine does not generate the same coil pulse as the 2F did so the tach, and consequently that function of the amp, do not understand the signal.
The amp is located right on the body of the AC unit under the dash, you can see it piggy-backed on there right under the glove box. It is basically a little circuit board that lets the AC know when the run, when to cycle, when to shut down.
The 62 operates a little differently than the 60 amp, instead of needing the coil signal to activate, it gets a signal from the ignition to deactivate. That means that if the 62 amp is used, your AC will work just fine, but will not turn off during startup.
The 62 amp is ALMOST a plug and play, there is one wire that needs to be pulled, I will have to check and see which one.
I have had the theory for awhile that if you actually jump the yellow wire (input) on the amp to the black wire (coil) that the pulse signal would trip, I have not tired it yet, but I am helping a Ghen with his AC issue right now and he is going to try it, if it works that will be the simplest route since all you will need is a short jumper wire. The next simplest step would be to swap in the 62 amp, there is no additional wiring need, just one wire has to be pulled, it uses the same style connector. It is just a good idea to get in the habit of shutting down the AC when you turn the vehicle off so the starter does not have to turn the AC pump when starting.

I'll look into finding a 62 amp (I have a friend who works on cruisers for a living so hopefully I can find one at his place). Let me know how your friend's a/c goes, that definitely sounds easier. On the other hand, in the mean time when you remember/ find out which wire is not needed on the 62 amp let me know also. Thanks again, this is really helpful.

P.S. What do you mean by it "won't turn off when starting?" I turn off the a/c in every vehicle I have before I turn the engine off as a habit, but in this case, are you saying at key ignition "off" the power is still going to the compressor pump (or engaged)? Are you meaning to manually turn off the a/c button to kill the power to the comp. pump (since the key doesn't turn it off right?)? Then therfore are you saying anytime the a/c button is pushed in (without the key turned on) it will pwr/ engage the comp. pump? Sorry so many questions, I just want to understand completely. Thanks again!

-roger

Hey Roger,
If you are already in the habit of hitting the AC button when you shut down then you are all set. I think that most mechanically inclined individuals do so, but in land cruisers (and most other cars) the amp actually serves to shut down the AC system during startup.
The AC will not run with the car off, the clutch will not engage or anything like that, but when you go to start the car again, the AC clutch will engage at the same time the starter engages and make it a bit tougher on the starter motor.

I also checked the wiring to jog my memory on the 62 amp setup, the one wire that is an issue is actually the coil signal wire (black[not black w white]) If that wire is no longer connected to anything in your harness then it is not an issue, but to be safe you can leave everything intact, pull the black wire from the plug on your harness and insert it into the blank spot in the plug above it. That blank spot is not connected to anything in the 62 amp and wont short it out.

Then the 62 amp is a plug-n-play. We will see how Ghen does with trying to fry his amp, because it would be nice to know that a simple jumper would fix the issue.

 

[rchalmers3]

Did you use the relay to switch 12v to the coil signal wire? I've been wondering if the amp would operate if it just had a straight voltage run to that wire, since it is technically supposed to run off a pulse.
Keep in mind that the coil signal is supposed to operate not only as a low engine speed cut off, but also as a cut off during starting so the starter motor is not turning the AC pump in addition to the engine.

I have converted my FJ to HJ and changed over to 24v in the process. So it's not apples to apples. However, what I did was to use a relay that interuppted the ground side of the pull in coil with the thermal cut off, the power side was interuppted with a low pressure cut off, and the 24v (run) feed for the comp feeds the load side to the comp clutch. Is that of benefit to you? It's how I wired around the amp without a ignition signal. I can scratch a diagram for you if needed.

Rick

 

[kevinmrowland]

Ah I see! (I think ;p)
You basically made your own amp, I like it.

 

[VTCruiser]

I'll try giving the 60 amp coil input 12V and see if it works, but don't hold your breath. The A/C is not at the top of my to-do list to get the cruiser back on the road. It may be a few weeks before I tackle the A/C.

- gehn

 

[kevinmrowland]

Sounds good Ghen, If I get to it first I'll let you know how it works. If you happen to fry your amp on my bad advice, GLTHFJ60 mentioned that you were heading this way after the build, I can hook you up with mine since I am using the 62 amp at the moment.