Can a bad blower motor module cause...

..the heater and air conditioner not to work properly? Right now the blower motor will continue to run. I unplugged it. Thanks, Jim

If your blower continues to run even when the ignition is off, then most likely you have a bad relay that's sticking. You'll find it under a rain shield on the firewall.

All the PA's I have seen have auto climate control and use the control module in leiu of relays.
The module 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 default voltage is 12V direct to the blower unswitched, therefore your blower runs all the time unless you pull the fuse, disconnect 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 25 or 30 amp fuse.

Thanks for the great info. But is this the reason the heater and air conditioner are not working properly? Thanks again, Jim

You need to give more detail on what is not working properly.

You need to give more detail on what is not working properly.

The heater and air conditioner will not work either while the blower motor is contiously running or is un plugged. I thought when I plugged the blower motor back in the air or heat would shoot out but its just one temperature all the time. Thanks, Jim

Check to see if the compressor is engaged and running when the auto mode is selected. You could have a blender door stuck on one position. Check the codes using the procedure below and write them down, then use the clear code procedure and try again. Drive it a little and see if any code reappears.

This procedure will work on 1992 and 1994 models with ATC, and may possibly also work on 1988-1991 models.

The diagnostic mode also contains a data list mode and an override mode.

Be careful not to select modes 01 or 02, as these are different modes, and may cause problems. :headshake

If you suspect you are in the wrong mode, press OFF repeatedly until you exit to normal mode. If the temperature display flashes for 2 minutes when the ignition is turned to RUN, a trouble code is set.

1. Turn ignition to RUN. Press OFF and WARM (temperature up) buttons simultaneously.

2. Watch the segment test, then the trouble codes will be displayed.

3. Code Key:

00 - No codes

10 or 110 - Ambient Temp Sensor circuit open or shorted.

13 or 113 - In-Vehicle Temp Sensor circuit open or shorted.

15 or 115 - LH Solar Sensor circuit open or shorted.

35 or 135 - Data Line failure - HVAC Control Assembly

38 or 138 - Data Line failure - PCM

40 or 140 - Driver Air Mix Motor circuit open or shorted, or not calibrated

48 or 148 - Long Term Freon Loss

52 or 152 - Keep Alive Memory lost; sets with battery disconnected

66 or 166 - Low Freon

A number 1 prefix indicates a history trouble code

4. Press OFF twice once codes are displayed to end diagnostic mode, OR to clear trouble codes, press FAN DOWN three times (make sure 03 is displayed).

Once 03 is displayed, press FAN UP to clear trouble codes. Then repeatedly press OFF to end diagnostic mode.