That's a problem on the heater control that is an old problem (search old threads and you can find talk about it). Mine will do that every so often - turn key off headlight switch to manual headlights and off then key back on and all good. Some wierd thing in the system - been doing this with mine for a lot of years (7+ years?)Intermittent problems are hard to troubleshoot. Maybe you did fix a connection. Maybe it’s like a starter where you tap it with a hammer when it’s not working and it works, but inevitably the starter dies.
Tough call is whether to replace the part you have on order, shelve the part in case it does go bad, or return the part.
I have an intermittent problem like yours, except when this happens the digital temperature does not light up, so I can’t even turn it on. Almost as if it’s not getting key on power. Shutting the key off and turning it on fixes it. When it becomes more persistent them once every few months, I’ll troubleshoot, until then I let it go.
I suspect it’s a stinking 17 year old relay.
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