Honeywell L4064 Installation Instructions Honeywell L4064 Specification Sheet Forced Air Control The fan and limit controller from Resideo controls high limit and fan motor in all types of forced air heating systems. The bimetal sensing element turns the fan on and off according to plenum temperature. It has mounting adapters for replacing devices, adapters for wiring convenience, and a strain relief bushing for preventing damage due to field abuse. These combination warm air fan and limit controllers are suitable for all types of forced air heating systems. The controllers have 2 switches; one which opens the limit circuit if the plenum temperature exceeds the preset safety limit; it resets automatically. The other switch turns the fan on and off. Fan is turned on and off according to plenum temperature. May be used with all forced warm air systems. All models may be used as limit controllers by wiring only the limit side. Limit contacts are suitable for line voltage, low voltage HKZ1208970