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Discussion Starter · #1 ·
I burnt up a A.C. clutch....didn't know why, I had a local shop install a new one (didn't have the tools to do it myself)After installing the new one, we turned it on with the fan switch in the low position and noticed that it was slipping.....we checked the voltage coming to the clutch coil it checked 7 volts(may have these mixed up)on medium it checked 4 volts....on high we had 0 volts.......Hummmmmmmmm.........at home I took the fan control switch out and opened up the tabs and disassembled the switch assy....looked O.K. inside but I had some electrical contact cleaner so I cleaned and reassembled the switch assy....put the harness plug on the switch and everything worked fine (didn't have a voltage tester at home, but the compressor functioned as it should) installed the switch, put all the tools away and went for a ride......quess what....No A.C........took everything apart again and noticed that by wiggling the plug the compressor would turn on......so I cut off the plug and soldered individual connectors to the wires and plugged them directly to the blades on the switch so as to eliminate the plug......when I checked the switch out( Blue wire to compressor) with a test light, medium and high had a bright light and low speed had a dim light.....I'm going to get a voltage tester and check but I think there is something else going on here......Everything was fine for a day (Fan on high) but now the compressor won't come on again........Need Help Again
Thanks in advance "Again"
Ken
:mad:
.....
 

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Take a look at the A/C portion of the schematic and get the meter out. The test light won't be of much help. Places like Harbor Freight have cheap ones that you can toss in the toolbox. They were on sale and might still be on sale for $3.00.
It's a dark green wire that goes to the clutch. Color must have faded. This dark green wire goes back to the harness connector, then runs to the compressor on/off selector switch. This switch works with the slide control level. From there the wire becomes a black/yellow wire that goes to the speed control switch (low speed). It ties on the same terminal as the black/yellow that goes to the resistor assembly under the hood.
The resistor assembly is a good place to measure the black/yellow wire.
The black/yellow (low speed) should alway have 12 volts if the speed switch is in low, medium, and high. If not, possible speed selector switch problem.
The dark green should have 12 volts if the speed selector switch is L, M, or H and the comprssor switch is on.
 

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Discussion Starter · #3 ·
Thanks John.......I'm going to get a voltage tester and then I will see if I am smart enough to figure out how to use it.......I'll post results........
Ken
 

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Discussion Starter · #4 ·
O.K.......Got a tester......looked at the wiring schematic.......time to get smart......Started the car and turned on the air to see if the problem fixed itself overnight......not a chance.........Checked Black/Yellow at resistor....12.5 volts......pulled off the plug on the compressor, checked green wire voltage....12.5 volts...hummmmmmm......put the plug back on compressor....nothing.......took it off again ...12.5 volts........put in back on and checked the voltage in the plugged condition....0 volts.......Repeat with same results.....where is the voltage going??????......left it on and went to check voltage at selector switch but B4 I could get in the car the compressor went on, checked voltage at green wire plug...12.5 volts.....I thought it could have been the cable control switch?????? I see in the wiring schematic that the battery is grounded to the compressor....I have the ground going to the block.......should I change it....I'm confused as to why I was getting voltage to the plug but lost it as soon as I plugged it onto the compressor in the beginning of the testing......Any Ideas?????
Thanks
Ken :confused:
 

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The voltage isn't going anywhere. What's happening is there isn't enough current to drive the compressor. When you pull the plug off, you see voltage. When you put it back on it "disappears". This effect is typical of a bad connection or a bad contact in the circuit.
If you see 12 volts on the compressor with the wire off, then plug it in and the voltage falls, follow the line back. By that I mean check the connections back near the switch with the compressor plugged in. It could be the harness connector doing it but willing to bet it's one of the switches. Example with compressor plugged in:
On one side of the switch will have 12 volts, on the other side it "disappears". Answer: bad switch contacts. Just like burnt car points.
Your problem is intermittent. That is, it comes and goes. You will just have to catch it when it's acting up to find what the problem is.
 

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Compressor switch:
Black/yellow- from control switch
Dark green - to compressor
Control switch(blower speed):
brown - from fuse
black/yellow - compressor switch
Check volatage drop across switch(s),voltage should be within .5 volts between wires colors
 

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Discussion Starter · #7 ·
O.K...........Here's what I did.....I know it's not right but.........I am almost positive that the fan switch is the culprit, since they aren't available and for the time being......I hooked up a fused manual switch to supply the current directly to the compressor independent of the fan switch........any problems in doing this until I can replace find a replacement switch....
Thanks all........
Ken :confused:
 

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The fan switch feeds the compressor switch,I would put your manual switch across the dark green and black/yellow(compressor switch) first.If the system works- its the compressor switch thats bad and if it stops working then you know its the fan switch. MIKE
 
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