My 1990 Buick Lesabre blower motor stays on all the time, we replaced the motor thinking it was bad but it still stays on all the time even when the key is off. Anone have any suggestions on what is wrong? Thanks!!

Without doubt, you have a very common problem on these cars, the (blower control module.) It is located on top of the fan box under the fuse and relay section on the firewall. It has two wiring connectors connected to it and usually three screws holding it in the box. You can get a new one from any dealer for around $150.00. It is such a common problem on Buicks and other GM cars with auto fan control, that the dealers usually keep a good supply on hand. You can also check your local salvage yard, (about $50.00) they usually have some at the front counter. Be careful to insist on the same part number as the one you have removed if buying from a salvage yard. (The part number will be on the module). GM made four or five different controllers that look the same, however do not have the same number of wires or the same functions. You do not have a relay for the blower fan because the controller sends varible voltage to the fan to control the speed. Usually the resistors fail in the module and the defult voltage is 12V direct to the blower unswitched, therefore your blower runs all the time unless you pull the fuse, dissconnect the battery, or pull the plug on the fan itself. The fuse is also located on the firewall with the relays. Pull the cover off and look inside the cover to locate the correct one. It is a 30 amp fuse.

A 1990 Lesabre does not have a blower motor control module. The blower circuit was redesigned in later models to support climate control.

Your problem is most likely that the blower relay is sticking on the high speed setting. The relay is found under a rain shield on the upper firewall next to a relay for the AC. To find the blower relay, simply disconnect a relay, turn the blower on and see if the blower works (it shouldn't will the relay connector off).

Thanks!!!! Will check it out!!!!!

Sorry, I am so use to working on 92 & up with climate control, I seem to forget about relay control blowers.

Hi All,

This just started happening on my 1988 LeSabre. Is this relay under the hood? Any idea what side it could be on. I pulled all the relays behind the glove box and it didn't control any of them. Any help is appreciated. This is my Gransmothers car and she is sitting at home while I try to fix it. I have temporarily wired it to a relay so it wont work when the key is off but would love to fix it right.

A 1990 Lesabre does not have a blower motor control module. The blower circuit was redesigned in later models to support climate control.

Your problem is most likely that the blower relay is sticking on the high speed setting. The relay is found under a rain shield on the upper firewall next to a relay for the AC. To find the blower relay, simply disconnect a relay, turn the blower on and see if the blower works (it shouldn't will the relay connector off).


Where did you get this Information? I had GM power control modules going back to the early 80's. I had one on my '85 Eldorado that went bad and just replaced one on a ladys '90 Olds Regency. These cars DO have power control modules and not just a simple relay.

Actually I forget what year they came out with auto climate control. It could have been 1991. I do remember replacing the module in a 91.


There were two types of fan speed controls.
1) The relay engage, resistor speed control
2) The module speed control, no relay engage.

It's been so long since I worked on a 90 model, I forgot what they have, however if it has auto climate control, it could have the module (no relays). If it is not auto climate control, it would have the relay engage-resistor speed control. The second relay is for high speed only.