I made my dash heat more effective!

[Groover]

This may be a timely topic for some. The dash heat in my coach was never very effective on the highway even though it is less than two years old. Traveling when it was less than 50 degrees outside was miserable.

First a little background information: I have a DP with a Tempcon heat/air unit and identical controls to older Ford products.

My first clue was when I noticed that after freezing for 200 miles on the interstate the coach warmed up a lot for the last 15 miles of a trip on back roads with lower speeds. My first thought was that the slides did not seal well and I was getting drafts. I even took the coach back to the builder to get that checked out but they could not find drafts. My second clue came on the way home: It was warm outside and I was running the airconditioner. It was also rather windy. I noticed that the output from the aircondtioner vents was varying a lot and sometimes would nearly stop. I switched to Max AC and got a consistantly strong breeze and was much more comfortable. It seems that somehow how speed combined with winds makes my heat and air unit loose volume unless the outside air door is closed and it only closes for Max AC.

Following this revelation I ran the airconditioner on max the rest of the summer and was reasonably comfortable without outside air coming in. With the cold weather coming up I decided to try that on heat. After not getting any help for either Thor or Tempcon I just cut some pieces of plywood to fit over the air inlet doors and ran a screw through the plywood into the door itself to hold the doors shut. (The doors are pulled closed by a spring and are shut by vacuum. Neither will be damaged by forcefully overiding it.) Low and behold I stayed much warmer on my first trip. I really did not miss having outside air with the heater any more than I missed it with max AC. I am trying to decide whether to just leave the plywood but eventually it might be nice to have outside air. I am going to keep my eyes open for a dash mount vacuum switch that I can add to manually control the air inlet doors regardless of the mode the Tempcon unit is in. My newer cars have that and it works well in them. I may also put a switch on the AC compressor so that I have the option of not running the AC when humidity is not a problem and I just want some heat. This control has 4 heat modes and the compressor comes on in 3 of them.

Running the heater in recirculation seems to let it heat the air a little hotter in addition to insuring good air flow all of the time. I would still love to know why air flow dropped off when I was in high winds but at least I have a solution now. If I get real ambitious I may try to put a bus type extra heater under the sofa. It sure would be nice if the controller was like the one in my van with an extra knob to control a rear heater fan. This seems like something the factory could have installed fairly easily and works well in my van that only cost 1/5 as much.

[Cloud_Dancer]

Exactly what does this mean? Can you say it in a different way (like for semi-intelligent hearing-impaired persons)?

"The doors are pulled closed by a spring and are shut by vacuum. Neither will be damaged by forcefully overiding it.)"

[wa8yxm]

There are good and valid reasons to want outdoor air,

I suspect I know what was happening (A vacuum was building up in the area of the outside air intake and thus preventing air entering the system) there are many ways to fix this.. I will not even try to list them since that is not my primary field. but

Rather than all that woodwork.. I would have simply disconnected the vacuum motor from the door and tied it open.

however that said: Good job on figuring it out, and your fix works.