Forum Discussion

horner's avatar
horner
Explorer
Jul 13, 2014

AC Relay

I started the engine ( Ford V-10 ) on my MH and put on the AC ( MH engine ) and I heard everything working. The problem was that no air was coming through the dashboard openings. I only got air through the defroster vents. My question is does this sound like a relay problem and if it is where is the relay located and what would it look like?
  • Most chassis AC air-direction controls are vacuum operated. Try to access the back of the dash controller. Most likely you have loose or leaking vacuum lines. Defrost position is failure mode for safety reasons.
  • Low vacuum caused by either leaking or demand from the engine will always cause the system to default to put air out the defrost vents.
  • Find your vacuum canister and make sure it still holds a vacuum.
  • Update on AC problem. The diagnosis was the controller and/or the little motors that open and close the vent doors.
  • Update to update. The problem was the vacuum modulator.