Recirculation Vent

[Fuzzybeard]

I'm looking at my options to improve Dash AC performance, which I know has been rehashed to death. My vacuum controls seem underpowered and I have as yet to find any leaks.

I was wondering if anyone sees a problem with locking the recirculation vent open and plugging the vacuum line going to the vent servo. Besides not being able to pull in fresh air through the AC/Heater, I can't see any downside. The roof AC can't keep the driver cool by itself so I'm looking at all options.

I'm working on adding extra insulation to the doghouse and I am planning on insulating the duct hoses which are open to the elements in the engine compartment. I have no problem with using the roof AC while traveling, but I have a single unit, a 30 foot RV, and 30amp service...though I may add a smaller unit in the rear bedroom.

[Skip426]

First thing to check would be the operation of a water shut off valve for the heater, when the dash controls are on max A/C, the valve if there is one should shut down the flow.
In situations on an older gas tow vehicle , I added a second vacuum reservoir to the system to prevent the loss of dash A/C control on long climbs at WOT.

[Fuzzybeard]

Originally Posted by Skip426

First thing to check would be the operation of a water shut off valve for the heater, when the dash controls are on max A/C, the valve if there is one should shut down the flow.
In situations on an older gas tow vehicle , I added a second vacuum reservoir to the system to prevent the loss of dash A/C control on long climbs at WOT.

Thanks,

I did check the operation of the valve and it all seems to work properly. I just thought locking the recirc vent open would not only improve the efficiency of the system, it would also decrease the load on the vacuum.

[Skip426]

A second thought , I always have them.
Between the intake manifold and the vacuum reservoir , there should be a check valve to stop the vacuum bleeding back to the engine. Another thing to check.

[Fuzzybeard]

I'll definitely take a look at that valve.

[Waiter21]

I can't think of any downside of constantly recirculating. I generally leave mine in recirc to gain the max A/C.

I don't have any problems with the vacuum controls on my Mirada. I did have a vacuum leak right after I bought it and it was constantly running the A/C to the defroster.

Heater A/C blows Defrost mode, regardless of switch setting | 2001 Coachmen Mirada 300QB

Yo probably have an Evans system. Their web site has a lot of good info. I linked to it in my article.

[Fuzzybeard]

Originally Posted by Waiter21

I can't think of any downside of constantly recirculating. I generally leave mine in recirc to gain the max A/C.

I don't have any problems with the vacuum controls on my Mirada. I did have a vacuum leak right after I bought it and it was constantly running the A/C to the defroster.

Heater A/C blows Defrost mode, regardless of switch setting | 2001 Coachmen Mirada 300QB

Yo probably have an Evans system. Their web site has a lot of good info. I linked to it in my article.

Great resource I am also enjoying your blog!

I realize now that I am probably not having vacuum issues since my dash air hasn't been diverting to defrost.

[Fuzzybeard]

Found one of the problems with the dash AC. The Evans housing was broken and had pulled away from the firewall. I "fixed" this by using fender washers to support the mounting points. The air is now blowing colder than before.....getting closer!

[Johndale]

On mine the main feed hose to the big accumulator on the bottom that feeds everything has a splice that goes to the connector. Touch it and you will find it will turn your hand black. And I took a vacuum checker from harbor freight and checked everything and found the blue hose to the max air door was full of pin holes. By looking at it it looked new and not brittle. Replaced the part under the hood and now it will freeze you out. This is my first trip after repairing it and added a little freon now dw is happy and so ami.


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