2000 Suburban
Front blower works on all settings except 5 (high).
Rear blower is intermittent and only works on 1&2. Went it starts working we do not turn it off and it will keep working upon vehicle startup.

Not sure where to start my attention. From reading other threads I see high by passes the resistor pack. Does it sound like the speed control **** or another relay that could be the problem?

Seeking suggestions.

 

Welcome to the forum.

If GM still uses a relay for the Hi blower speed, then that's where I'd look first. Usually find burned contacts.

 

where is the ac relay on 2000 suburban?