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Cold air in rear seats


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Recently did a trip with quite cold OAT at 12.5k and my family in the back froze!  There is a lot of cold air that comes up from the left rear seat gap between the seat and the airframe.  The heat was on.  I know about the valve at the pilots knee - I assumed closing it would send hot air backwards, opening it would send hot air to my feet.  Moving the valve didn't seem to matter.  This may just be a byproduct of an old airplane but was curious of anything I could check (that wouldn't require major surgery).  Thanks!

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  I grew up in the back of an early m20c, and it was always cold back there (the early C's didn't even have the duct to the back seats that your valve connects to).  The joke we had was that the pilot and front seat passenger faces melted off, but the back of their heads froze...the back seat passengers just froze.

First place to go as far as I understand is the wing root seals.  Unscrew the little angle strip that goes around the base of the wing and replace the duck tape (many people use gorilla tape, I believe they make a wider version that covers the gap more readily). I don't think my father ever tumbled to the wing root fix that I have heard is very helpful.  I did one side recently and will probably do the other side at annual.

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There are several threads about this on MooneySpace. Use Google to search "mooneyspace cold back seat".  I personally sealed everything as best as I could and made a tube that attaches to the heater duct below throttle quadrant and goes to the back seat area.  I have flown when it is -20 F across the Sierras, Nevada and Utah in the winter and this helps the backseat tremendously.   There appears to be very poor mixing between the front and back of the cockpit.   Without the tube we overheat the front two seats and still freeze the back.

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The valve by your knee determines whether the warm air is cabin heat or defroster.

In my C, even in single-digit temps above the Ohio River, I rarely kept cabin heat pulled out even halfway, and then with the vent knob pulled out almost as far. Toasty warm, gloves off, coat opened up; then rewrap scarf, zip coat and pull on gloves before opening the door to step out!

Much less of an issue here in Sweet Home.  :D

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1) The tiny tubes that deliver air to the back seats are tooo tiny... if refreshing the tubes go larger diameter... if not refreshing the tubes... they are probably crumbled and deteriorated... find the 1” holes in the side wall of the cabin... 

2) The air leaks at the wing roots are too big...

3) OAT at 12k’ is too cold...

4) Heat generated at 12k’ is too little... as MP is also too little.... (biggest challenge)

Work on getting everything sealed up right to defend against the rest of the list...

We hung a blanket/tunnel to direct the warm air towards the back where the back seaters legs went...

Search around here for heated blanket ideas...

Dang it’s cold up there....

Great PP memories..!

Best regards,

-a-

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As stated above, pull the back carpet and seat, then seal everything with aluminum tape.  It will definitely help.

The other place to seal with foam or insulation is the hole to the battery/radio racks in the tail.  There’s a reasonable hole there for all the wires and if it isn’t sealed it pulls air forward.  The hole is in the back baggage bulkhead along the pilot side.

It can be fixed with a little easy work.  My F is comfortable in Washington state in winter.  No jacket required front or back except for safety gear!

Edited by Ragsf15e
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2 hours ago, steingar said:

I took the blankets that I put on the nose to keep the engine warm during the winter months and stuffed them onto the hat rack.  Solved the problem.

Yes, a lot of cool air comes forward from the hatrack and leaks in the luggage compartment.

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