Two days ago the check engine light came on. At Autozone they hooked it up and diagnosed a possible catalytic converter related problem–but said it didn’t seem urgent. The 2nd time I restarted the car that day (after Autozone), the climate control blowers got stuck on high and won’t turn off. This has happened once before for a day or so about a year ago and the problem corrected itself. This car has 84,000 miles. Any thoughts?
The electronic speed control module has a bypass relay that is used for the highest speed setting. It sounds like yours is sticking. You can probably hit it to unstick it, but you really should replace the module. They are not very expensive. I’m sorry, but I don’t know where yours is located. It will be mounted somewhere in the airflow near the blower. This is like a blower speed resistor, but it is electronic instead. (The module has a transistor, a relay, and a few other components.)