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RV anti-freeze question

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donc13

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Re: RV anti-freeze question
« Reply #15 on: January 04, 2022, 08:08:01 am »


- Set the Ford cab HVAC to "recirculate" to prevent outside air from entering through the dash vents.


The 'motor' that holds the HVAC door in the 'recirc' position needs vacuum to hold this position. After the vehicle is off for some time, the HVAC reverts to fresh air intake.  As far as a  model years 1999-2007 anyway. Not sure on later.

The lack of vacuum also directs the air out of the windshield defroster vents, so a blanket laid across the base of the windshield may have some benefit.  Again, 1999-2007 models. Not sure on later.

My 2014 chassis does the same.  Like 2 Frazzled, we do the same, set the vehicle hvac to OFF when we stop at a site.
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mikeh

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Re: RV anti-freeze question
« Reply #16 on: January 04, 2022, 08:31:47 am »

- Set the Ford cab HVAC to "recirculate" to prevent outside air from entering through the dash vents.

The 'motor' that holds the HVAC door in the 'recirc' position needs vacuum to hold this position. After the vehicle is off for some time, the HVAC reverts to fresh air intake.  As far as a  model years 1999-2007 anyway. Not sure on later.

The lack of vacuum also directs the air out of the windshield defroster vents, so a blanket laid across the base of the windshield may have some benefit.  Again, 1999-2007 models. Not sure on later.

Ford hasn't changed.  Even with the vacuum reservoir and check valve that's in the system to help retain vacuum (when driving in a "low vacuum condition"--under prolonged acceleration for instance), the system eventually reverts to default when the engine is killed.  Any effort you might want to direct toward air infiltration should be focused on the defrost vents.
« Last Edit: January 04, 2022, 08:41:20 am by mikeh »

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Ron Dittmer

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Re: RV anti-freeze question
« Reply #17 on: January 04, 2022, 09:30:08 am »
I learn something new all the time.

Everything people are sharing here makes perfect sense.  When the E-Series chassis is parked for extended periods, the dash HVAC will slowly loose it's vacuum and automatically adjust to the default defrost setting.  I like Volkemon's idea of placing a blanket on top of the dash over the defrost vents, if you want the RV closed up tight.
 2o2
« Last Edit: January 04, 2022, 09:32:19 am by Ron Dittmer »
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