The idea that the heater needs turned on is usually related to bleeding the cooling system after the flush. If the heater blower motor isn't working, you could simply select heat.
As far as flushing the cooling system, you can still do it. Here is a link that explains how it's done:
Also, there is a video at the end of that link you may find helpful.
Let me know if this helps or if you have other questions.
Saturday, October 30th, 2021 AT 10:07 PM