Dash Air Temperature Rises As Speed Increases

[raibourn]

I drive a 2017 Thor Aria 3401, my first class A motorhome.  

At idle, the dash air blows cold as it should, but as I increase speed the temperature rises. 

I have had it checked by the dealer who is telling me that the rise is small and within expected parameters and that this is normal in a class A. 

Can anyone tell me if this is true? 

If not, any suggested remedies.

[wolfe10]

raibourn,

Welcome to the FMCA Forum.

Assume you are talking about a temperature rise while using the dash A/C.  If so, your condition is contrary to what one would expect.  That is, that with more engine RPM, the A/C compressor turns faster and SHOULD cool better.  We generally raise engine speed to recharge a dash A/C so it can move more Freon.

Have you felt the hoses to the heater core?  More engine RPM also means more coolant circulation and if the valve is not completely closed, this could cause your condition.

[rpelatt]

I keep a thermometer like this: https://www.grainger.com/product/35HV46?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!166591779552!!!g!370218741819!&ef_id=WKnhCQAAAD0FzW19:20171129181604:s&kwid=productads-adid^166591779552-device^c-plaid^370218741819-sku^35HV46-adType^PLA attached to an AC vent. This way I know if the AC is blowing constant temps. Your increase in temp. could possibly be coming from the windshield, or other source of radiant heat.

[dickandlois]

The increase in the Temperature could also be related to the increased coolant temperature.  The scenario could be - the seal between the heater section of the AC / Heater box is not sealing completely. 

Bad seal material, poor application of the seal material, Wrong material, improper thickness of the material, bad adjustment and settings of the door / gate , defective vacuum actuator and or a low or restricted vacuum - that does not allow for adequate travel of the actuator.  

Try running the AC in recirculate mode. This closes the system to outside air flow.  This limits the heat built up in the engine compartment. With a Diesel pusher - outside air temperature is what you get

The mixing box is setup so the outside air enters over the AC evaporator first then into the heater section to set the desired temperature and to also lower the heat in cold weather when one is in the defrost setting.  A preset point of heat to cold. 

Rich.

[fagnaml]

Raibourn --

First, welcome to the forum!  You will find forum members to be very helpful and supportive! 

I had a similar issue with my dash A/C in my 2007 Damon Astoria (which also was manufactured by Thor).  A engine idle speed, the air from the dash A/C was quite cool.  However when driving the air from the dash A/C became quite warm.  A very astute, young mechanic at RV Masters in Houston diagnosed the problem as a partially to mostly plugged low pressure refrigerant return line from the dash to the A/C compressor on the engine.  As Brett described, as engine RPM increased and the A/C compressor speed / refrigerant flow increased the plugged low pressure return line could not handle the increased flow.   The bright, young mechanic replaced the lower pressure return hose and solved my dash A/C problem.

By the way, the new Thor Aria is an updated version the Damon Astoria.  The floor plans of the Aria and Astoria are nearly identical and terrific!  My wife and I have had much enjoyment from our Astoria with no major problems.  I'm sure you'll have many great adventures during the coming years with your Aria!   Congrats!

[Rewillia]

Recently experienced a similar problem in the my dash AC would start by blowing cold air then turn warm after a period of driving. End result being I had a bad heater control valve up front on the generator slide bay that was not closing completely and allowing hot water to circulate hence defeating the efforts of the AC. Once replaced, the dash AC works as it should.

 

[chesuncook1]

Raibourn

Not sure if the AC problem has been cured. We own a 2017 Aria 3901. Our AC would seem to work for a short time and then be warm. In the front of the coach, to the left of the generator is a small radiator looking part of the AC system. It has an electric fan on it which was not plugged in. I had to cut some wire ties in the harness nearby to find the other end to plug the fan into.

When you turn the AC on do you hear that fan screaming? It's real noticeable.

Hope this helps.

[wolfe10]

1 hour ago, chesuncook1 said:

Raibourn

 In the front of the coach, to the left of the generator is a small radiator looking part of the AC system. It has an electric fan on it which was not plugged in. I had to cut some wire ties in the harness nearby to find the other end to plug the fan into.

When you turn the AC on do you hear that fan screaming? It's real noticeable.

 

What you are describing is a front mounted  A/C CONDENSER.  Some are front mounted, some mounted in the side in back.  Absolutely, without air movement over the condenser, it can not remove heat from the interior.

[five]

I did the numbers, and on our coach, we burn less fuel in an hour running the 10KW Onan and the roof air (s), than running the dash air.  Once I turn on the dash air,  the big fan starts, and fuel mileage drops about two MPG.

[wolfe10]

Yup, no "one answer fits all" here.

Absolutely if the A/C condenser is in front of the engine "cooling package" AND (yes big AND) that triggers the high HP fan to HIGH, it will have more impact on fuel mileage than running a generator powering one roof A/C.

But, not true if the A/C condenser has a separate 12 VDC fan or if it is in "back" but does not turn the big cooling package fan to high.

Knowing what you have allows you to make smart decisions!