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wesnsue

Dash vents cut out on a hill.

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I have a 2015 36ft HR with a gas v10. When I drive up a hill (doesn’t have to be much) the fan on the dash quits & goes to the defrost. It doesn’t matter if it is outside are, AC, or heat. The Ford truck & RV center had it for 3 weeks & said it was an actuator. They said it was an RV problem. Then the RV repair (where I bought it) center replaced the actuator with no results. After 4 weeks in & out of there shop they gave up saying it is a Ford problem. The Ford truck center does not want to see me again. I now it is a vacuum problem but where? Where is the vacuum reservoir on a class A gas rig?

Wes

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Wes, Welcome to the FMCA Forum !

Totally agree that there is a vacuum issue.

This Video might help find a hidden issue with a primary vacuum leak on V 10 engines. The fault codes listed also can come up, as the mileage on the engine increases . The Vacuum leak can cause converter failures down the line over time.

Rich.

 

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Rich, I'm curious as to how a vacuum leak can cause converter failure on a Ford F53 V10 chassis. 

Thanks
Richard

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3 hours ago, RLS7201 said:

Rich, I'm curious as to how a vacuum leak can cause converter failure on a Ford F53 V10 chassis. 

Thanks
Richard

It will lean out the engine causing it to miss fire, thus damaging the catalytic converters. 
That was a great question.

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18 hours ago, jleamont said:

It will lean out the engine causing it to miss fire, thus damaging the catalytic converters. 
That was a great question.

DUH! Brain fart on my part. I thought he meant torque converter.

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2 minutes ago, RLS7201 said:

DUH! Brain fart on my part. I thought he meant torque converter.

LOL, I did at first also. 

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My bad for not saying Catalytic Converter. I had only the engine in mind when I posted the Vacuum issue thoughts. Like, keep an eye on the one on the left-How fare left are you referring Sir?

Rich.

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My first thought was 12 volt to 120 converter, then I shook my head to clear that thought, LOL.:P

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Appears that OP got no help at all.  Vacuum leak or check valve is first thought has nothing to do with spark plugs or Catalytic Converter.   Please find where vacuum line comes through the firewall and trace to leak or check valve in both direction.  

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On most Ford products the problem is usually in one of these plugs. They are notorious for coming loose, another problem area is at the dash pots (actuators) those come loose also and leak. 

Locating these under the dash of an RV could be a difficult task. 

Vacuum.jpg

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1 hour ago, jleamont said:

On most Ford products the problem is usually in one of these plugs. They are notorious for coming loose, another problem area is at the dash pots (actuators) those come loose also and leak. 

Locating these under the dash of an RV could be a difficult task. 

Vacuum.jpg

Interesting thought Joe ! From the OP it sounds like things work with the  AC / heat ducting vacuum switches, but the system defaults to the defrost mode only when the engine is under an increased load while going up a grade. I might be missing something ?

Rich.

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I have had them leak, not disconnect unless kicked which results in "stuck on defrost" complaint. Most times you can disconnect and reconnect and they stop leaking and it solves the loss of vacuum issue that is sounds like the OP has. 

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5 hours ago, DickandLois said:

but the system defaults to the defrost mode only when the engine is under an increased load while going up a grade. I might be missing something ?

I  think defrost is the default any time it looses or doesn't have vacuum.

Bill

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If the a/c vents work normally under normal driving conditions, the leak could be anywhere. I would start looking for the vac reservoir and testing the vac signal in and out. I have had many reservoir tanks crack (plastic). just a thought 

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There also should be a check valve to hold the vacuum to the HVAC system when accelerating.  Even with a good check valve a leak can also be the source of failure.  

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Think if you look at the video on my first reply on July 15th. the mechanic shows a bad spot in the Positive  crankcase Vacuum line running between the intake manifold and the PCV located in the Valve cover. Not an uncommon issue with the V-10 series engine. Also the V-10 / Trident does not have a vacuum reserve tank. Big Gas power engines make allot of vacuum. The small 4 cylinder and 6 cylinder engines do not make a large source of vacuum.

For a Trident to loose vacuum, there is a rather large leak or hole somewhere. Same goes for the  8.1 L V 8 engines.

Rich.

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