I am having an interesting issue in my 91 740 turbo: every so often it seems that every so often the speedo, tach, cooltant temp, and fuel gauges go inop. By that I mean they behave likenone of them are getting power. But later on the same day they come back to life. It may be coicidence but it feels like that usually happens first thing in the morning; at first I would guess humidity but AFAIK the power wire to those gages in the cluster come straight from the fusebox. Where else should I be checking?

If this matters we may have a clogged ac drain (clogged enough to drip inside while also drippri g though the drain).