Dash A/C Compressor Clutch Fuse Slot Has Failed

[deandec]

Thank to everyone for helping this failing Brain of mine regain the correct direction.

I have installed a new ATO fuse holder from the post with the ignition wire to the other assigned post for the Compressor Clutch wires.

It now works like before including the little indicator light..

So simple, but I made it way too complicated.......

[deandec]

Originally Posted by YC1

With the fuse out, use a burnishing tool/points file to clean the connectors. I know, no one has one of these anymore. A piece of sandpaper folder in half with some glue in between can be used.

Then use a tool to try and spring the contacts closes a bit. If that does not work. Bend the fuse blades a bit off center and see if they make better contact.

Not the perfect solution of course but might help you diagnose the issue.

Thank you Myron. I will do this when the temps get reasonable out here.

For now the substitute fuse will do the trick for adding the 134a to the system.

[spinroch]

Lots of good Ideas here.

[deandec]

Originally Posted by spinroch

I believe there is a negative lead at the top of the Buss bar. (The white lead). This would be needed for the LEDs to light up.

The fuses are to protect from over current flow. Too much current can cause damage & fires.

It's like water in a pipe:
Current flows through the wire, like water through a pipe.

Voltage is like water behind a dam. Voltage is the potential energy, like the pressure on the dam wall.

You need a 12 volt test light and a cheap multimeter. The Harbor freight ones are a good place to start. Everyone has their own opinion about this. I have many types of multimeters... the cheap ones I use in the car & RV. If you break them, you can toss them and get another one. You can learn how to use them on YouTube.

Try temporarily connecting the IN and the OUT sides of this circuit at the Buss bar with an equivalent pigtail fuse available at any auto parts store. This will tell you if your suspicions are correct.

I have several multimeters, and am very dangerous when using them....

Why do you indicate connecting the fuse via a fuse holder and the two existing wire posts should be "temporary" .

[deandec]

Originally Posted by YC1

Take that large wire off, cut it back and put a new connector on it. Clean the post until it is shiny. A tiny wire brush on a dremel tool works a treat.

I think you have an IR drop. That is, a bad connection and you are losing it.
As suggested, you can jumper it but you already know you are not getting the voltage.

Always fix the obvious first. That is, if you see something that does not look right, fix that and often other issues will clear up.

The wire from the ignition solenoid to the center row of fuses does not appear to be burnt but I will clean it up. With the new bypass fuse all the indicator lights light up, including the one that did not.

There is a small resister in the board adjacent to each fuse socket. I assume that it is there for the led light bulb.

I suspect something has happened in the fuse socket and will investigate at a later time per your recommendations.

How do I measure for an IR drop with a multimeter in this situation?

[YC1]

You kind of already nailed the IR drop. That is, you had a voltage drop from the input of the fuse holder (ignition controlled power), to the output side (air conditioner compressor).

IR drop is just a fancy term for there is resistance and the voltage is across that resistance.

I know, clear as mud. Sorry.

I think I got lost somewhere and missed something. Are you saying NOW all the leds are lit since you installed the new fuse?

If so I really would like to see a new picture of your fix. If they were supposed to be lit before and just now are lit then you fixed something else. If this IS the case then that input wire that looks like it was overworked and somewhat melted and suggested to be cut back and cleaned up has improved its connection from perhaps adding a new fuse holder.

If this is the case, your old fuse holder slot may be working now. That wire was a glaring issue for me.

[deandec]

I measured the voltage at the load side after the new fuse line was installed.

It is the same as the chassis battery voltage, which is about 11.8 dcv.

This is the fuse block end of the ignition solenoid wire.




The ignition lighted center row of fuses including the one that previously was not lighted. The new fuse holder is at the right side of the picture, which has the fuse block displayed from left to right rather than top to bottom



Except for needing to charge the chassis battery, I think things are back to normal.

[spinroch]

Good Job on locating the problem area on your fuse panel. Sorry.. I meant "temporary" as a troubleshooting technique. Systematically track down the issues and deal with them one at a time. Which you did! I should have finished up by saying "If this works, install the fuse holder as a more permanent solution" Which you did.
Nice work!