View Full Version : ghosts in the machine!!!!

03-23-06, 03:05 PM
Hey again everybody. I posted a few days ago, but got no responces. I thought I'd try it again, as I could really use some ideas from people that may have gone thru this. I have a 1997 Catera, and the other day i got in, started the car as normal, and a couple of minutes later, this happened. The blower fan (the heater-a/c fan) just turned on all by itself, on HIGH speed! I couldn't do anything to stop it or even slow it to a lower speed. I even unplugged the hvac electronic console...still nothing, fan kept running on high. It even runs with the car turned OFF. I finally had to take the main fan fuse out, so as not to run down the battery. I have no heat or a/c at all like it is now, and hot weather is around the corner. I could really use some ideas on this one. Hopefully someone has gone thru this problem and may be able to help. Thanks, Marty

03-23-06, 06:03 PM
Hum... A relay might have become stuck open or something to that effect, that or the HV/AC controller is malfunctioning.

I'd start checking the relays... in the owners manual pgs 6-57 through 6-63 list all the fuse and relay locations. Major one I can think of is #33 - Blower Controller, A/C Compressor Relay ... as you can see in the manual there are also others like #10 as well (Body Control Module, Heater Water Auxiliary Pump, Fan Control Relays, Auxiliary Water Pump Relay) ... anything to do with the Blower fan, BCM or H/V/A/C.

Another situation is that maybe the blower fan itself is malfunctioning.

Time for hands on diagnostics... and if you need the owners manual, I can give you the link online or you can search the forums.

Hope something helps.

03-23-06, 06:38 PM
I do have the owners manual, and I bought the 3 volume service manuals as well (I could tell Im gonna need them with this car...lol) Thanks for your input, I'm gonna check all the fuses and relays tomorrow. Maybe I'll get lucky!

03-23-06, 09:03 PM
Does the service manual have a wiring diagram that includes the Blower motor? What diagram would that be under? That would help narrow down the list of components to check. Relays would definitely be a good place to start.

I've wondered this about relays before, so I'll ask it here: How exactly do you "check" relays? Just plug in a replacement?

03-24-06, 05:27 PM
You, know, that's a good question. I said I was gonna check mine, but I have no idea how to tell if they're bad. And who has extra relays laying around that they can just plug other ones in. Not me, that's for sure. So I'm wondering too, how do you check a relay?