having some electical issues, I think my bcm might be going out?

when I got the car about a year ago the rear defroster would not work, I figured it was a fuse. I have since ordered a full set of Factory service manuals and removed the back seat and probed around with a volt meter. I have found that the big relay that controls the rear defrost is getting voltage to the coil when the defrost is turned on and there is voltage avaialbel for the defrost grid, but it doesnt work, I am thinking the grid is bad at this point, but I dropped it and never got back to persuing it.

Recently my passenger side seat heater has stopped working , and this morning I put the front defrost on and was getting warm air out of the drivers side defrost and cold (lik AC cold) air our of the passenger side defrost vents. I fooled around with the passenger side temperature zone control and could not get any change.

I will also add that the passenger size slider temp control has never really seemed to work, if I have the temp set low enough that the ac comes on and the passenger slides the heater control over to heat, it only seems to slow down the fan for the entire heating cooling system with no change on the passenger side temp.


anybody have any input?

1998 Buick Park Avenue Ultra

Check your temp door linkages- pull down the glove box to see what it is doing- go from full hot to full cold- see if doors move freely- one on top , on on bottom of HVAC case...

Last one I did- had the temp door linkage popped off the pivot arm...

hmm, now that you mention it, I did hear a pop the other day when it was shifting from one blower zone to the other. I will check it out on my lunch break.

ok, I opened my glovebox all the way and looked bakc behind there, I could not see anything moving. I could see what I beleive to be my BCM but no ductwork. I suspect it is through the glovebox hole and up? I already had a group of gawkers here at work watching me (they obviously had nothing better to do) and didnt want to have to start climbing arround upside down and such in khakis and a polo.

go from full hot to full cold- see if doors move freely- one on top , on on bottom of HVAC case...Did you follow the instructions above and nothing moved?

I still have not identified any duct work, I need to crawl up under there a little. All I can see is a black box with eletectical connectors, I am assuming the ductwork is up in there a little ways.

Another thing I will add to this puzzle is that it is most definatly AC coming out of the passenger side when heat is coming out of the driver side. It is not like outside air temp, it is cold and dry like ac.

ok, so I dug arround in there a little more last night and I cannot see anything move at all.

I looked in the factory service manual and I dont see where I would see anything move? I see the air mixture motor they refer to (to the far left through the glove box hole) but all of that should be internal right?

Another note, when I transition from heat to ac (adjust the internal temp) I dont hear anything going on in there.

I also read in the FSM that when you put on the front defogger that it kicks the ac on as well, this makes sence if the passenger air blend is not working for whatever reason and no hot air is making it in, then all I would feel is ac coming out of the defogger vent.

temp door arm is external- as well as actuator- should be white plastic- with adjustacle threaded rod- very easy to see on top of HVAC case-- did you drop the glove box (swing it down) to the floor? To get a better view?

I am not seeing this at all, do I need to start removing stuff to get to it? Here is what I am seeing

http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11562.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11541.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11542.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11543.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11551-1.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11551.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11552.jpg
http://i28.photobucket.com/albums/c208/cutlass1972/buick/101708_11561.jpg

Yes- You have to get back to the HVAC case- looks like the BCM is right in front- unclip it and let it drop to the floor- hopefully you have the hush panel out above the passenger footwell....

I will have to look into it tonight after work. MAN, they REALLY shoehorn the shit in there these days. I miss my 70's cars where you could climb up under the dash and have a party under there.....

ok, so maybe I am exaggerating a little bit.

ok, I finally got in there. Mine is NOTHING like yours guys. Mine actually has a motor that mounts to the side of the heater box that turns a white plastic knob that sticks out. It mounts right to the knob though as opposed to some actuator linkage. The motor only controld the passenger side hvac, once I removed the motor then turned the white knob by hand until there was heat coming from driver and passenger side the passenger gets whatever the driver gets. Now I need to find a replacement motor assembly.

In the mean time bigger problems just arose, I hit a deer on monday doing about 50mph. Now I have to find a replacement hood, grille, condenser, radiator, radiator core support, driver headlamp assembly, and driver fender. anybody got a donor car they want to sell near KY?
http://i28.photobucket.com/albums/c208/cutlass1972/DSC_2071sm.jpg