That's what I see in the diagram on the two heaters and the relay and triac.
The blower is not running. It only jerks quickly twice or thrice.
I think it is either in the blower motor or the inverter. I think I'll go for the motor first, then inverter. I'm not just sure where to get the inverter replacement. I'll check the store nearby this week.
Thanks for your help, applianceman.