AC Bypass (1 Viewer)

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So recently I got a new job and picked up a truck to be my DD. After 7 years of driving my cruiser every day and about 70k miles it was time for her to have a break. It sat for a while at my parents while I got settled, recently when I brought it up I found my AC stopped working. After some digging I found that the AC controller wasn't working properly, I found this out by just connecting my compressor to the battery directly. All the pressures on the AC are right and I am currently bypassing the AC controller by jumping the main power wire to the line going to the compressor.

My question is, how bad is doing this? Basically the ac compressor is just turning on with the AC switch. I can't really think of a reason how this would hurt things, apart from a pressure spike trashing the compressor. Am I overlooking something or is this a decent temporary fix until I can source a new AC controller?
 
The amplifier might be the problem, but it could also be the pressure switch
I wouldn't recommend running it like your hotwiring trick too long . The compressor needs to cycle on and off
Where is the pressure switch located? And I figured, currently when I'm driving it I'm just manually switching it on and off every few minutes or so.
 
Where is the pressure switch located?
Its near the evaporator in the plastic heater/cooler box passenger side under glove box.


If you bridge the 2 wires to the switch and it starts working again, then the switch is the problem. It's either no good or low on gas.
You can leave it bridged and it won't hurt anything.
 
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Its near the evaporator in the plastic heater/cooler box passenger side under glove box.

Perfect thank you
 
If you leave it jumped, the compressor won't ever cycle off and then the evaporator will freeze and restrict refrigerant (and oil) flow to the compressor and you risk damaging it.
 
If you leave it jumped, the compressor won't ever cycle off and then the evaporator will freeze and restrict refrigerant (and oil) flow to the compressor and you risk damaging it.
What is the cycle time for the compressor? Are we talking 5 minutes or 30 minutes?
 
It will still cycle with the pressure switch jumped. The switch is there to protect the system from low gas.
The thermostat controls the cycle. Mine cycles approx every 1 to 2 minutes
 
It will still cycle with the pressure switch jumped. The switch is there to protect the system from low gas.
The thermostat controls the cycle. Mine cycles approx every 1 to 2 minutes
So if the issue is the pressure switch, bypassing it should allow for a temporary fix with minimal harm?
 
Are you sure the amplifier is your problem? Have ypu checked it for power to it? I wouldn't run it the way you have it for very long.
 
Are you sure the amplifier is your problem? Have ypu checked it for power to it? I wouldn't run it the way you have it for very long.
I do know the amplifier is getting power because I jumped it at that connection. So it either has to be a bad board or a bad pressure switch.
 
Ok, I have an 83....I got a new compressor and everything all sealed up almost two years ago. During the fix the amplifier board kept going out. Would run for a bit and then crap out, so I bypassed the AC amplifier. I run a weber carb so didn't need it to adjust idle when I ran the AC, just so it would cycle the compressor. My temporary fix, which is still this way two years later, was to stick a digital thermometer into my AC vent and I just cycle the compressor off manually by hitting the AC button. I will wait until the air coming out gets close to freezing and turn it off and then hit it again once the air hits around 40-45. My AC blows very cold and as long as I dont let it freeze up it will not cause any damage.

I saw a post on here once with a small device you could order off of amazon and it had a probe on it and you could splice it in and set upper and lower limits and it would cut power to the compressor off and on. I sent that guy a message in hopes of getting more details, but he never answered, Needless to say that life and other FJ60 projects got bumped higher on the to do list.
FJ60Paddle.JPG
 
 
yeah, if you look at the thread it ends with me asking a few questions....I DMd the guy and didnt get an answer. I just need more info about how to hook it up. Wish there was a write up on it.
 
The picture of how he did it is there, though it's not very good. Looks like he wired the stock harness where the amplifier goes ...

Description is vague, too. But He's still on mud ... Maybe he can elaborate...

@GarethsSixty

??

Also, not sure if @Engineer8000 has any interest in repairing / rebuilding these A/C Amplifiers ?


1627841276280.png
 
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I would be happy to check out the AC amp. The FJ62 version is fairly straight forward. I even have some of those T2333 ICs. I don't know what the transistor is but I'm guessing a 2SC945, I have some of those as well. If you are handy at all, and you suspect the amplifier is not working, reflow the solder on the connector pins and see if that fixes it.


The picture of how he did it is there, though it's not very good. Looks like he wired the stock harness where the amplifier goes ...

Description is vague, too. But He's still on mud ... Maybe he can elaborate...

@GarethsSixty

??

Also, not sure if @Engineer8000 has any interest in repairing / rebuilding these A/C Amplifiers ?


View attachment 2747464
 

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