This 2000 Oldsmobile Intrigue came in the complaint that the a/c vent positions could not be controlled. It would just blow out of every location a little, but no where with any force. This Olds Intrigue has auto a/c controls. It has an electric over vacuum control system for operating the door positions. The first thing to do was to drop the hush panel, under the passenger side of the dash and check for vacuum supply to the reservoir. Vacuumed is supplied on the black hose, with the engine running of course. I found good engine vacuum at this location.
The next step involved locating the vacuum relay assembly. It too is under the passenger side of the dash. It is however closer to the right kick panel area, as shown below.
I think, there should have been two screws holding it in place but there was only one. A sign someone has tried to find the problem before me.
With the relay assembly hanging, I started the engine and held the unit in my hand. I then started moving the mode button to force the system to shift locations of the air flow. I backed this up by looking at scan data on my Tech 2, to see if the control head was working correctly. All scan data seemed okay but I noticed that the relay assembly was chattering, instead of having distinct clicks. My years of experience told me that this was likely due to low voltage.
With a quick look at some wiring diagrams, I found that the relay assembly only had one power supply wire, Brown. With the ignition switched on, I found that there was only 6.68 volts present on the Brown wire.
In researching I determined that the brown wire was supplied voltage from the HVAC fuse, at position B2.
I checked voltage at the HVAC fuse and found it only slightly higher, 6.94 volts.
I also determined that the open leg of the fuse location marked as Low Blower was supplied power from the same source as the HVAC fuse. I connected a long test lead and fused jumper wire to the battery positive terminal, Then connected the other end to the open Low Blower fuse terminal. I did this with the ignition already on, so that the vehicles systems would not be confused by the signal. In fact the engine was running. When the power was supplied, the voltage as expected came up to battery voltage and the vent controls started working properly.
Time to replace the ignition switch. I am not including all of the details of replacing the ignition switch, as that information can be found in other posts and service manuals. I am including some relevant pictures for what is distinct to this vehicle brand. The lower dash covers need to be removed. The radio needs to be removed (do not disconnect the radio wires unless you have the theft lock code) and the instrument cluster needs to be removed.
Notice the two 7 mm headed screws in the picture below. Both of these screws are used, along with one of the radio mounting screws, to hold the ignition switch bracket in place.
A view of the ignition switch from under the dash with the lower panels removed.
With the key switched on, the locking tab for the shift interlock cable has to be depressed, so that the cable can be pulled from the switch. Turn the ignition back to the off position before removing the electrical connectors. Be careful while trying to rotate and remove the ignition switch and bracket from the dash. It still has the anti theft sensor wires attached to it. It will cost another couple of hundred dollars to replace that, if you damage it. For those of you with scan tools make sure there are no anti theft codes in either the PCM or BCM before starting. If there are replace the lock cylinder kit ,as well as the ignition switch at the same time.