97 Bonny Dash Electircal wierdness

[ThreeDot]

1.) Whenever I drive in a heavy rain, the climate control reads -38 outside temp, and I can't use A/C on auto unless I drop the temp to min and run it full blast, 'cause the car thinks its cold so even at 65 degrees on the climate control, it blows heat.

2.) DIC blinks/flashes/generally acts the fool at seemingly random times while driving. Rapping on the display or beating the ^&** out of the top of the dash will get it to quit for a short time (seconds).

3.) Blower sometimes will not work after the car has been shut off and restarted. No ammount of fiddling will get it to respond. The first time it happened , I pulled the motor to replace it, decided to test it one last time and it worked fine. Put it back in and it ran fine for a couple of weeks, then quit again. went out the next morning and it worked again.

4.) lights for the oil/volt/temp portion of the instrument cluster quit, occaisonally will come on again if I rap on the display.

I have theories, but I want to hear what you folks have to say.

TIA,
ThreeDot

[randman1]

The ambient temp sensor sends a varying voltage to the HVAC programmer to indicate outside temp. As temp increases, the resistance decreases. This indicates either a short in the wire or a faulty sensor. I had to change my sensor because it was reading 168*. They are less than $20 and very easy to replace.

I'm on my second cluster in my 93. The first one flashed similar to yours along with malfunctioning oil, temp and boost gauges. The second is better but the oil and temp gauges are still wonky. I don't think that the electronics are the best in these clusters but would think that by 1997, most of the kinks would have been corrected. Some people have corrected their similar problems by disconnecting and reconnecting the electrical connector(s) in the back of the cluster making a better connection.

I'm scratching my head on your blower motor problem. Usually if the Blower Control Module is at fault, it either doesn't work at all or always runs (even with the key removed from the ignition). I haven't seen a BCM be intermittent like you describe. If you have a volt meter, I would start by testing the control wire from the HVAC programmer to the BCM (it's gray on the 93 but may be different on yours). The range is from about 2 volts for low to about 8 volts for high. Maybe do a temporary connection to the wire above the hush panel in the passenger's foot well so when it happens again, you can easily read the voltage. If it is more consistent of a problem, you can test it right at the BCM under the hood.

Your gauge backlighting problem sounds similar to the DIC problem and again think that poor connections are to blame. Along with the 1 or 2 connectors that plug into the back of the cluster, there are several interconnect cables from board to board within the cluster. You may be able to correct be disconnecting and reconnecting these too.