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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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The diode is merely there to absorb the big SPIKE created by the clutch coil (collapsing field) when it is disengaged. This dampens the spike that would typically back-feed into the rest of the electronics. The system should still run without it (but needs it only for protection)

When tested, the diode will show continuity ONLY one direction, but not the other.
If it is blown.. it will short the system.

You should also be able to "temporarily test" the system without it.
If it's bad, you definitely want to replace it.
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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Incorrect.. when diodes blow (in this type application), they typically pass signal in both directions (no longer functioning as a one-way device). This would suddenly pass signal to ground.
This diode (in this application) does not pass current (it is not in series with the supply voltage). In this spike dampening application, the failed diode would most likely become a short.

Simple test.. pull diode and see if A/C engages.
Or actually test the diode with a VOM meter.
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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It should ALSO be noted it appears the diode CAN accidentally be plugged in backwards.
It appears there is NO obvious visual polarity direction.
If it was plugged in backwards, it would have blown (shorted) it as well.

  • Again, the system WILL actually run without it (although it should be for testing only).
  • I tested with my diode removed and it worked fine.

It's certainly possible with the blown diode shorted to ground it may have also damaged the relay (or possibly something else). Make sure fuse to this circuit is good. Normally try swapping relays. If relay is not at fault, you'll have to do some trouble-shooting.

This diode is not normally carried by many LAPS.. but it is available on Amazon/Ebay.
I think it's rating is 1amp (nominal) since it does not carry any continuous current.
Be sure to plug new one back in correctly (polarity--see photos below)
Electronic component Rectangle Machine Circuit component Plastic

Rectangle Font Lego Gas Toy


Don't forget (according to schematic) the "A/C REQUEST LO" to compressor goes through the low-pressure switch on the accumulator/dryer. This connector can be jumped for testing purposes.
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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Again it WILL run without the diode. (for testing purposes)
If it's not working without it, then something else is wrong too

PS: Good to know the fuse block is "keyed" so it can't be put in wrong.
Also, good job in finding the elusive part number and replacement part
 
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