Intermittent power failure to heater AC interior fan cluster on 2004 Buick Regal?

This is not rare issue.This problem is very much seen on Buick car models and also other car models.
Basically this is caused by problem with ignition switch.
Also the other parts like fuses and relays needs to be inspected,including wiring short.
I will provide you some details with diagrams to troubleshoot the issue:---
First of all confirm with a 12 volt test lamp when the condition occurs however this is very likely an ignition switch failure.You need to see if there is power at the hvac, low blower and cruise fuses in the instrument panel fuse panel when the condition is occurring. There is one contact inside the ignition switch that often burns due to the current draw of the blower motor being relatively high. It shares it's voltage feed with the cruise control. So first get confirmed with a test lamp .In most cases the ignition switch should take care of your concern.

The schematics wiring diagram is as follows :---



  1. I am having this problem now. For a month or 2 the blower would just go out and come back on at random times and I noticed the cruise light on the dashboard would sometimes flicker and I realized one night that whenever the blower would go out the cruise would not work either. Now for the last week or so it has all been dead. I came across your post and it sounds like the same exact problem.

    I checked the primary side of the 3 fuses you mentioned and get 12v to all of them with no fuses plugged in. After some poking around I found the following.

    1) With only the cruise control fuse plugged in I get 12-13v on all 3 of the connections
    2) With only the HVAC fuse plugged in I get about 2.8v across all 3 connections.
    3) With only the Low Blower fuse plugged in I get 12-13v on all 3 connections when the blower switch is off but as soon as I turn it to any of the speeds it immediately drops to a few millivolts.

    I'm thinking the contact is burned and acting like a kink in a hose and as soon as you put a load on the other end, the voltage drops because that kink (burned contact) prevents the wire from handling it. Because of the heavy load, the blower drops it to almost 0 volts while the HVAC is not as heavy a load and cruise is an even lighter load and doesn't have much effect on it at all. All the fuses are fine because none of the devices drew an excessive load and the problem is on the primary side of the fuses.

    I opened the panels under the steering wheel and am able to see the orange wire mentioned above and put a meter probe on it right where it goes into the harness and was able to see everything I mentioned above happen right at that connection. I want to take the switch out completely and mess with it but I cannot figure out how to remove the tilt lever to get the shroud off. I would also like to take a wire right off the battery and connect it to that orange wire bypassing the ignition switch contact to see if the stuff works before buying the switch assembly as it is not cheap. Let me know if this makes sense to you. Thanks.

  2. For Tilt steering removal detail and diagram,check the link mentioned below:---
    Buick Regal Tilt Steering lever Removal?


  3. Thanks. I will mess with this today and hope it is only the switch like you said. Would you happen to have any more of the wiring diagram for the 04 regal? I would like to see the rest of the circuit in case it is not the switch.

  4. Well, after pulling apart and sorting through a big ball of spaghetti down by the ignition switch wiring harness, I found that the people who put the alarm in my car cut some insulation from the orange wire and wrapped a wire from the alarm around it to get alarm power. Although sloppy, it gave me an easy spot to tap into and I brought a wire from the battery to that same spot on the orange wire bypassing the burnt contact and everything worked again proving that it definitely IS the ignition switch. Thank you for this great post.

    Now, I cannot figure out how to remove the ignition switch on this car. Do you have any instructions on how to do this? Does the steering wheel or the ignition cylinder have to be removed first?

    What I found was that the orange wire DOES have enough juice to click a heavy duty 12v relay so I was considering cutting it and using the switch side to power a relay and running battery power through the relay to the fuse box side of the orange wire instead of replacing the switch since it seems to be a real pain to remove. If the contact completely burns one day I will have to change it but being the relay coil only needs around 70mA it may hold up for a long time without any heavy load on it. I would like to replace the switch and do it correctly so if you have any info on removing the switch it would be greatly appreciated.