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Cadillac Repair/1999 cadilac eldarado


QUESTION: my ac is working but the main blower dos not work at all in any speed , the rear fan works blowing cold . I have power to the motor so I replaced the blower motor and still no fan what could the problem be?????

ANSWER: Hello,

Another fine notorious Cadillac issue. You have one of two set up in it. You either have a fan speed control resistor module mounted on the passenger side of the plenum under the hood. This module is non-serviceable and is about $400.00 and the last I heard, was not available any longer.
You will see where the heater blower power wire leads to this module.
There is a way to jury rig the blower so that you can get High and off.
Generally though, when these resistor modules fail, they will un the battery flat as well leaving the blower running.

Check all fuse boxes before getting deeply involved in this.

The second design is in the BCM (Computer)which controls the fan speeds. This portion of te computer can be bad.

At either rate, this was a problem that the factory had new under warranty. At any given time in the era, it was very common lace to see the hoods up and blower resistor modules being replaced. The resistors control blower speeds and were  built inside this module.

It was a very stupid designs and I think very few GM models used it. It is as stupid as the Cadillac specific trunk pull down, which too as well as their power antenna masts that failed.

Cadillacs are a great car. I have had over 25 of them, but some of their designing was doomed for failure, yet they did it for years and years.

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QUESTION: Where could I find these (scm) (bcm) locations on the car?
And how could I rig it up to high and off?


This method is not listed in any manual, but we had many customers over the years have their vehicles modified in this matter just to get high blower and off.

Go to auto parts store and purchase these items: Package of yellow butt connectors, package of 10 10 gauge wiring, in line fuse holder, package of 30 amp fuses, (highest rated two throw toggle available), package of scotch connectors for 10/12 gauge wiring, roll of electrical tape, can of silicone spray, cheap test light,zip ties (medium length) and if you don't have, a cheap wire splicer/cutter. You will need a steel coat hanger as well.

Tools required: Drill and drill bit for mounting toggle, 10 mm socket and ratchet, 7 mm or 9/32 socket or nut driver.

Open the hood. Disconnect power wire at blower and give yourself about a foot of wiring if you can before cutting the wire. Take the coat hanger and straighten. Pull the new wire out of its package. Put both ends together and cut in two halves. Take one end and strip it. Bend an end of the coat hanger so you can place the stripped end of the wire on it and bend the end of the hanger over it as tight as possible. Get as compressed as possible. Then run the wire even with the hanger for an inch or so, and take your electrical tape and wrap no more that two wraps holding the wire firmly with as little profile as possible. Go in the passenger compartment on the drivers side. Remove hush panel (Black plastic on bottom of dash. Hopefully you have a 7 mm or 9/32 nut driver to remove the hold down screws. !0 MM or wingnuts hold the panel to the firewall. Remove hush panel.
Go back under hood. You will see on the driver's side firewall a grommet having a mass of wiring protruding. Spray that grommet real good with silicone spray. Without tangling or scraping any of the existing wiring, take the straight end of the hanger that doesn't have the wire attached and poke through the grommet pushing the hanger into the drivers side passenger compartment leaving about 6" of slack in the coat hanger under the hood. In passenger compartment bend the coat hanger giving you leverage to pull. You may have to wiggle the coat hanger back and forth, but the purpose is to feed your new wire into the passenger compartment.
Once pulled through, leave enough wiring so you can attach to the blower wire and for it to connect to the blower. Take your in line fuse holder and place between the end of your new wire and the wire for the blower. Strip the ends of the wires. Attach with butt connectors and to insure a tight connection, tape both ends. Take the zip ties and attach your new wiring to the factory harness after you have reconnected the blower wire. Go in the passenger compartment and take most of the slack out of your new wire.
Under the steering column you will find two harnesses coming from the electrical ignition switch. Use your test light and poke into the thicker wires on at a time. You are looking for switched power This will be power only when the ignition is turned on Off, the test light will not light. Use a scotch lock connector that will wrap around your power wire and secure.
Strip the wire end of your new wire and attach to the terminal of the toggle switch. Take the half of the new wire you did not use and strip n end and attach to the other toggle switch terminal. Cut this wire giving yourself some slack (You can always gather together with zip ties if too long) Attach the male scotch connector to the other end of this wire and plug into your designated switch power wire with the scotch lock. Tape to secure.
Go under hood and install 30 amp fuse.
Go back and turn on ignition. Flip the toggle one way and you should have high blower and flipped the other way will be off.
If you can, you may want to drill a hole in the hush panel to mount your toggle. Reinstall hush panel and you are done!
Shouldn't take over an hour for a novice.

Good luck!  

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Rob Painter


Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?


Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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