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Hello, I have a question about three fuse holders with fuses in them under the glove box of my 1994 cutlass ciera s. I did some investigating with pulling these fuses and testing for power. Two have power one does not. Traced the wires they seem fine. One fuese turns off lights in cabin and makes the door locks click. The other interferes with radiator fan working and cuts power to sensors in the engine compartment. The third is a mystery as it has no power. I would like to learn what these fuses are for especially the third one with no power. Just a side note when i turn on the air conditioning on with the fuses seeming to have something to do with the radiator fan pulled out and then put it in place the compressor clicks on for about two or three seconds then the fuse pops. Thanks in advance.  

log in... check the Messages to the left of where you log out at..

i have know of a thread offsite.. has just the info you need...  

wayne, that thread had allot of info in it. But I did not see anything helpful for me........


jdirk79  

the car owner on that thread was working with those three fuses in the glove box.....

i think either he or i posted a diagram for that exact circuitry...

i have been doing about a dozen other things in the last little while...

i will see if i can find you some more info....

autozone.com does have wiring diagrams on that car....  

Hey wayne I went through that thread again and read it in full detail. I also looked at every link and read through allot of them. They do have allot or circuitry Info for allot of things. They AZ site was also good. However nothing really to tell me what those three fuses in holders are for or what circuits they belong to. I admire how you worked extensively with rooster. That was quite a bit of troubleshooting. So listen Im hoping maybe we can go through some trouble shooting of our own. Where do we start? I travel long distance for work and really need this car on the road. I drove my old ladies 09 toyota with only 12k at the time and in one year its ended up with 88K. She is not too thrilled.

The car is running fine to tell the truth. Everything else I have fixed is doing well and the car purrs nicely in idle and drives nicely as well. However the heat is just around the corner in my part of Texas and I don't want to fry driving around in the car without the air conditioning working properly. It tries but like I said when I turn on the ac that same fuse inside of an inline fuse holder pops and heats up quite a bit. The same fuse rooster pointed out in one of his photos along with the z connector.  Though it seems like there is hope because the compressor clicks on and tries to run but stops as soon as the fuse pops.


jdirk79  

thats an interesting failure...

do you have an ohm meter??????

or do you have a Harbor freight tools near you ...  


these do have a problem failing sometimes....



this is bolted to the front of the compressor..  behind the pulley...    when the system calls for the compressor to turn on...  the relay closes .. the windings on this create a magnetic field and that pulls the steel clutch shoe into the face of the spinning pulley causing the compressor to spin with the pulley driven by the belts..... this allows a mechanical connection to be controlled with electronics...

the problem .. these coils have a tendency to burn out ... in most cases... the clutch cycles off and on .. allowing this coil to cool slightly as the pulley spinning creates a LOT of air motion but.. just barely enough to keep it from overheating...

when the system is run on max cold...  for extended periods on really hot days... at low speeds.. temps under the hood are going to soar...

this is not something for the average person.. or even normal mechanic.. it takes a few special tools to get down to it on most applications..    unplug it...    work the system..   if the fuse blows.. then the short is elsewhere...  perhaps burned at the relay connectors..

so... if you can reach it.. unplug the connector right behind the ac compressor clutch pulley..  i don't do a LOT of AC service.. there are specialists for it in most of the shops i worked at..  i mostly did the vacuum and electronic controls... the compressors and evacuating and recharging along with flushing the system was done by others...

unplugging is just for a test...    does it blow the fuse unplugged.. as it is the end of the circuit...

if you have an ohm meter.. you can OHM the coil..  i looked but did not see the resistance measurement.. but its going to be very low..   probably below 4 ohms..  maybe below one ohm..   it does show as a high amp coil winding... so the difference between a normal coil and a dead short are going to be hard to measure with any ohm meter..

harbor freight does sell the plug in amp meter that rooster got.. you might get a quick reading with that .    you will probably find that 15 bucks very well spent for a diagnostic tool..  there are 2 different versions.. one for the TINY fuses and one for the conventional sized plug in ATO fuses..  

look under engine electrical at the AZ site...  there might be something on it..

i have changed coils on the larger compressors.. but that takes i seem to recall one of the small ones..  

I think I see where you are going with the compressor coil being bad. Would I be able to tell if the coil was bad running it straight to the battery with an in line 20amp fuse I put in between the comp. and batt. The reason being is because I have done exactly that and the compressor runs just fine, the clutch engages fine too with straight power. So ??? I'll try running the system with the comp. pigtail unplugged from the compressor and see what happens.

I do have a dmm I just bought the other day. I just am not to sure of how to use it. I have the basics down of whats what on it ac/dc V, ac/dc A, ohm/continuity etc. etc. and how to probe. I guess I'm just not that confident with it yet. Do you mean to check the compressor pigtail plug for continuity and see how much the resistance the meter shows on the screen?  

if you can get to the AC compressor plug behind the pulley... not all are easily accessed...  unplug it..   set your digital volt meter to 200 OHM scale..   probe the coil connector.. NOT the harness..    i have not found what the OHM spec should be..

http://www.harborfreight.com/30-amp-automotive-fuse-circuit-tester-67724.html

with that... you can plug into the fuse and monitor the amp draw.. see how much amperage..

 

this should be the proper wiring diagram for the AC and cooling fans...



you will want to print the above image..  

Hello Wayne, Well i checked for voltage at the compressor coil plug by probing the terminals. Neg to Neg Pos to Pos. I got a reading of 13.7 in dc V. I tried to measure V in ac but I would get a reading of .03 that would eventually go to all zeros. Note the car key was on the on position and tested it again with the car running. Did I do it right?

Like I had mentioned way earlier I had charged the system by running straight power to the comp and condensor fan from the battery. Well the connections were still there. I had both components hooked up to toggle switches. So I unplugged the toggle switches and unplugged the compressor coil plug before the testing I mentioned above.

So after I got the 13.7 dc V reading I decided to connect everything back up the way it was from the factory. I turned on the car and turned on the air conditioning. The fuse rooster was also working with was not in its fuse holder. When I put in OH MY GOD my ac started to work. Both fans worked and the compressor was running but I never saw it cycle though. Anyway it ran for a good thirty minutes the fuse did not pop. I ran through all ac setting and cold to hot and the heater all was well.

I shut the ac and the car off and took the key out. The aux fan was still running. It would not shut off. I hit the relay a little and it turned off. I turned on the car and repeated the whole process and again the fan would stay on. This time I wiggled the wire at the aux fan relay and the fan would come on of on of on of. Could this also be why I never saw the comp cycle? Sticky relays? Maybe they have continuity when the car is off? I'm excited but also concerned. From Texas on a hot day......


Jdirk79

p.s all the wiring seems in sync with the diagram. I took of the dash and pull all the wires from the engine compartment. Looked ok....  

relays are cheep... compared to the rest of the parts...



i am only hoping that something that drives the relays did not get damaged...

DC volts is the correct ...   on most autorannging meters..  there is a button.. where when you have voltage displayed.. you can push the button and change the location of the decimal point to change the range of the setting..  sometimes it will stay in than range until you turn the big knob or shut it off..

sorry.. i hate autoranging volt meters.. as when i am going down a row of circuits.. having to wait while it goes through all the ranges is a pain.. i have several meters..  the one i used the most is not autoranging.. but the autorranging meters i do have also have settings the non automated meter has..  dont forget.. i used these daily..  not just once in a while..   i think i am up to 8 different volt meters..  but i always have 2 in my tool tray..

when relays are removed from their sockets...    sometimes one can gently use 2 small screwdrivers or probes and extract the circuit board from the bottom..  sometimes the cover comes off..    please .. scratch a location on the relay so you know which one came from which socket...  

lets talk about how the relays work in this circuit..

see the pink wire leading into the relay diagrams above.. that is the power for the winding..  and on the compressor relay the power for the AC compressor clutch also..

on the pusher fan relay at left..  the dark blue wire goes to the ecm.. when the ecm commands the fan to come on.. it connects the dark blue wire to ground..  this creates the magnetic field that closes the contacts to allow power to flow from the red wire through the relay to the pusher fan..

on the primary coolant fan relay..  the pink wire again is power for the windings..   the red wire is power for the contacts..  the dark green wire is drawn wrong. it actually goes to the ECM where like the others.. the ecm can connect it to ground as it wants   to activate the circuit..

on the ac compressor clutch relay.. for some reason.. they used the pink wire to both power the relay and to power the compressor clutch winding..    probably  in looking at the circuit.. as the 3 relays use almost NO amperage to operate the windings..  this let the compressor clutch  on its own 10 amp fuse..  

i think that i would not just change the ac clutch relay..  i would also want to change the relays of anything else that was staying on.. when the key was off.

i might even go as far   and this is what i would do.. if it were my car..  think long and hard before doing this..  find the ac compressor relay..   cut and splice the 2 pink wires into the socket and provide them with its own power wire from a terminal block  with a 10 amp fuse..   why...  if the compressor clutch takes out the fuse..    you will not loose your 2 radiator cooling fans..  so you might get hot in the car.. but your engine won't overheat..

this drawing is not a GM drawing..  it is a aftermarket drawing done by a company to clear up how the circuits work..

i will have to double check this drawing against the 90 manual i have.. and the 97 manual i have see if it compares..

warning..   the circuits to the ECM ..    the relay coils take less than ONE amp of power to operate..     if yo go probing around and do it wrong .. you can blow out the control electronics in the ecm..      sometimes they are protected by advanced devices.. to prevent this.. not always..

so be careful..

more to come in a little while...  

the drawing of the diagram...  is probably correct.. but you may need to verify which wires go to which relay...

as i looked in my 90 GP manual...   there are several variations on how the circuit is wired...

looks like they redrew it to bring several pages of diagrams onto one page..  

Well after endless hours of working on the ciera I am pretty familiar and 99% sure the wires going to the relays are connected the right way. Also the ac system working I think back s it up too. I could be wrong but I think I'm right. Were you saying verifying which wire goes were so I can splice the two pink wires going to the clutch relay? What do you mean by a terminal block? Would pictures help wayne?


Jdirk79