Originally Posted by semcha
I have a part that I think is the vent door actuator in the dash to control switching among the AC, heat, and defrost vents. Part is L1596 on a 1994 Itasca Suncruiser on an F53 chassis.. Yellow vacuum line is attached to it. Problem is the vent won't change from the heat vent, so I think maybe it is seized. I can't find this part anywhere. Any ideas what to do?
Sean, I'm sure you thought about these but just in case:
1) Usually those actuators have a rubber diaphragm that connects to a metal lever. When vacuum is applied, the diaphragm contracts pulling on the lever. When there is no vacuum, a spring pushes the lever back in the other direction.
Can you move the metal lever by hand? If so then the vent is probably not seized.
2) Those vacuum lines are notorious for getting small leaks. Are you sure the hose is good?
3) The vacuum lines in many cases connect to a rubber coupler or fitting. Sometimes those are right angle fittings. They are also a problem in that the rubber deteriorates over time and leaks.
4) There are probably check valves and a vacuum reservoir in the system. These can sometimes fail as well.
5) Finally, the control unit mounted on the dash with the knob that controls vent/defrost/floor/mix/etc..can also develop vacuum leaks.
On my 2003 coach, I had a mess of vacuum problems due to aging of the parts and a rodent attacking the hoses. I bought a low cost hand operated vacuum pump at Harbor Freight that really helped to troubleshoot the problems.