Problem: The fan runs continuously (longer than 19-minutes) when the key is removed. The symptom is a dead battery. The fan turns off only when the ignition is turn off then on. 99% chance the fan timer is bad. Usually happens to the 90-93 Accords.
Solution: The reasonable solution is to replace the timer control unit. Before replacing the unit it would be prudent to troubleshoot. When the fan does not turn off after 15 minutes swap the cooling fan relays in the engine fuse compartment with another identical relay. If the fan refuses to turn off replace the fan timer unit.
Replacement: Remove the access panel on the driver's kick panel and search for a box way in there the size of two cigarette packs with 8-terminals. The 86-89 Accord fan timer unit is located under the passenger seat. Unbolt the unit and swap it with a new one.
Note: the fan timer location is a bit more to the right compared to this image. It's right next to the main relay like this image (as seen the main relay removal page.)