93-Z34 Lumina AC ??

[enjenjo]

Sounds to me like the compressor clutch diode is bad. recheck those two leads with the ac off, and with the ignition off. Also check the resistance on the clutch. And check that one of the wires actually has a ground. If the compressor diode is bad it will send the relay power right to ground, blowing the fuse.

I have the compressor unplugged, completely out of the electrial loop, and it still blows the fuse.

Is there anyway they can check circuit in the ecm??

If the compressor diode is bad it will send the relay power right to ground, blowing the fuse.


Even without the compressor in the circuit, the compressor diode is still hooked up. There are multiple things hooked to the same ground as the compressor. The diode is there to keep these other circuits from powering the compressor if there is a bad ground. The bad diode allows the power to go from the power wire directly to ground even with the compressor unplugged.

The compressor relay is grounded through the ECM, the compressor clutch grounds directly to the chassis.

[34ford]

Thanks for having the patience with me on this one. It has been a real brain twister. I really appreciate the help.  Now if I can only find the diode. I was assuming that it was in the compressor clutch pack.

Any guess as to where I might start to look. Won't be on it till tonight if all goes well.

thanks

bob

[wayne petty]

this is probably too early a connector for your car.. but you can see the clutch diode hooked between the crimp connections..

http://delmarwire.com/images/prod2120.jpg

theory .
the diode dampens the kick back voltage in the circuit when the circuit is shut off.. the collapsing magnetic field can create well over 100 volts. that will damage the ECM ...

here is a later repair harness when the diode blows out or SHORTS out..

http://delmarwire.com/images/prod2121.jpg

when it shorts out.. it becomes a complete circuit in both directions and blows the fuse..


the links came from this site...

http://delmarwire.com/prod21.htm

there were just so many drawings there i wanted to point out just what you needed to know..


does your digital volt meter have a diode test setting ... most do...   it will be a right arrow to a vertical line and then a minus sign.. ->|-     with the other end of the circuit disconnected ...  and the pigtail disconnected.. you probe the connector one direction.. you will either get 1 which indicates open.. or around 480... then reverse the leads..
you will get the other reading...

480 and 1

or

1 and 480...

in diode test the volt meter is actually passing a small amount of current through the test leads to measure the diode..


this should be what the clutch coil connector looks like...

http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/drm/85145/2/image/4/

but i don't see a diode on this version..  

its shown above in the diagram...

the delco # is a PT209

http://images.whisystems.com/smartpages/partinfo_resize/DCL/PT209.jpg

[wayne petty]

i did find this...

http://www.4s.com/Upload/Four%20Seasons/documents/Tech%20Tips/English/4S%20399%20GM%20DIODE%20INSTALLATION.PDF

GENERAL MOTORS DIODE INSTALLATION

When replacing an AC compressor clutch diode with a new GM diode, the part does not come
with an instruction sheet on how to install. The diode is made into a plastic case with a wire
coming out of each end. One end of the case is marked with an "X", and the other end is marked
with a "Y".

The green power wire for the clutch should be attached to the white wire on the "Y" end of the
diode. The black ground wire for the clutch should be attached to the "X" end of the diode.

The GM part number for this diode is p.n. 12126478

The AC Delco part number is p.n. PT 748
GM has also approved a diode from Radio Shack for the compressor clutch. The Radio Shack
part no. is 276-1144. If this part number is not in stock, and you are offered part no. 276-1103,
DO NOT USE IT, it is not approved for the compressor clutch.

this is the proper radio shack part number link..

http://www.radioshack.com/product/index.jsp?productId=2062579

a 3 amp barrel diode..

the BANDED side of the diode goes toward the GREEN WIRE...


i am still looking for specs...  

i don't know if any of the part numbers i listed have that diode already installed..


you might also want to read this page also..

http://www.motor.com/article.asp?article_ID=591


everybody might want to book mark the LINK below..

http://www.bcae1.com/relays.htm

then when they have some time.. read through it..  or save it ...


additional info..



Here is some more info from a previous discussion months ago......276-1141 diode ( 3A Barrel diode ) from Radio Shack for in line @ alternator on 12V Conversion..Find an epoxy rectifier... should be 3a, and 200piv or better.. they even have some 6a jobs that are 100 piv or better... just about any silicon diode of 1a/50piv will work.. and for durability.. go for more A and more PIV

1N5404 Diode - 3A / 400V Rectifier - DO-201AD package size.
1N5408 Diode - 3A / 1000V Rectifier - DO-201AD package size.


http://www.allelectronics.com/make-a-store/item/1N5408/3-AMP/1000-PIV/1.html

http://www.allelectronics.com/index.php?page=seek&id%5Bm%5D=pattern&id%5Bq%5D=1n54&x=0&y=0

[34ford]

Wayne,

Thanks again for the response. Like the article at motor.com. That sounds like the problem so now I need to dive into the wiring harness and see if I can find the little rascal. That will not be for a few days.

bob

[tomslik]

should be right at the clutch connection.

[34ford]

should be right at the clutch connection.

Wish it was that easy. there is no diode in the first 8"or so of the lead to the compressor.

Here's what my plug looks like that connects to the compressor, no diode
http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/drm/85145/2/image/4/

[tomslik]

you sure it's a 93?

what's the 10th digit in the VIN?

better yet, shoot me the VIN up to (and including) the 10th...nothing after that matters to me..

[34ford]

you sure it's a 93?

what's the 10th digit in the VIN?

better yet, shoot me the VIN up to (and including) the 10th...nothing after that matters to me..

Yes it is a 93 Lunina z34

vin # 2G1WP14X2P

thanks