furnace blower will not come on

[craigcnatl]

i have a 1991 lennox furnace. when i set the thermostate to heat i can hear the flames start but the blower motor will not come on. a few moments later the flame shuts down. any ideas on how the repair this problem?

[Hube]

IF your meaning the Main FAN, then check for a faulty fan Relay... Does the burner kick in, and how long until the burner shuts down ? . Please describe in minutes and/or seconds how long from the time the burner lites, until it shuts down. Does the thermostat activate the fan when you switch it to "fan on". Post back with info and we will advise as to problem. Hube