Aerostar -87 horn and cruise failure

Trying to repair horn and cruise control failure.
Fuses ok.
When pressing horn button, relay clicks somewhere under dash but could not
yet locate where. Did not find horn itself either. Can someone tell where are those located ?
Cruise main unit seems to be behind battery, vacuum hose goes through firewall but could not locate where. There's probably a vacuum pump under dash. Is it so that the vacuum pump should start whenever cruise switched on, even if the car not moving ? Any ideas about typical failures (switches on steering wheel, vacuum pump, control unit, accelerator cable, brake light switch et.c.) ?
br Vesku
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