Dash A/C question

[kwalker50]

We bought a new Winnebago Intent29L in July, but due to a factory recall on the dash A/C units, we just picked it up (again) today. They said that they fixed the unit, but my husband thinks that the output in the register (using a HVAC thermometer device) should be between 45-50, but the reading on ours is still between 55-65, and the outside air was 72. We were just wondering if this is the norm for ALL gas Class A dash A/C units? We are just frustrated with the dealer and Winnebago since we have only had the unit home for a total of 2 weeks since we purchased it back in July. Any advice or suggestions would be greatly appreciated! Thank you!

[dougrainer]

imgoin4it wrote:
dougrainer, only owned the Newmar for 10 years and there is a dial thermometer stuck in the dash outlet and one in an RV air outlet that gets moved from front to back from time to time and I guarantee that when the compressor is running it will be close to 40 degrees. An0ther old rule of thumb is that with compressor running an automotive outlet air temperature will be about half of the outside air temperature/ That's basically the temp that is coming off the coil. What do you suppose the temperature is just before or when the coil frees up and the unit goes into defrost mode. If your coming through Alamogordo you have an open invitation to stop by and we will check it out

I have been working on and fixing Motorhome Dash AC systems for 38 years and still working. I also have worked on and fixed Newmars for 25 years. 40 degrees is NOT a standard or benchmark for a Motorhome AC system. If you look at the links I posted, that Evans Tempcon system is what is used in your year Newmar. Look at the chart, 50 to 60 output above 80 degrees is what is standard. The system CANNOT freeze and there is no defrost mode. Your model DOES have a mechanical tstat in the evap, but it will never have to trip the compressor OFF because the evap will never get that cold. As I stated, you CANNOT compare Automotive rules of thumb or benchmarks on a Aftermarket Motorhome AC system. I take issue with what you stated because just because yours gets to 40 or you actually believe it gets to 40, you post that ALL should do that. That is not correct, which is WHY I posted the actual guidelines. Dial Thermometers ARE NOT accurate. Doug

[wolfe10]

One of the big variables in temperature delta between incoming and air exiting the vents is HUMIDITY.

It takes a lot of BTU's to condense water. Suspect dew point in the summer in Alamogordo is in the 40's, while in the DFW area in the low 80's. BIG difference.

All that condensate coming out of the evaporator case costs cooling!

[imgoin4it]

dougrainer, only owned the Newmar for 10 years and there is a dial thermometer stuck in the dash outlet and one in an RV air outlet that gets moved from front to back from time to time and I guarantee that when the compressor is running it will be close to 40 degrees. An0ther old rule of thumb is that with compressor running an automotive outlet air temperature will be about half of the outside air temperature/ That's basically the temp that is coming off the coil. What do you suppose the temperature is just before or when the coil frees up and the unit goes into defrost mode. If your coming through Alamogordo you have an open invitation to stop by and we will check it out

[rgatijnet1]

I use a hose to spray water on the condensing coil out front. Then I look for the lowest reading on temperature inside with a temperature probe. It should be close to 45 if things are working properly. Then, once you remove the water hose, the temperature will GO UP to reflect the AC capacity based on the ambient temperature at that time. Using the hose always give me the "best case scenario". The "real world" AC temperature output will always be higher.

[dougrainer]

imgoin4it wrote:
If I don’t get near 40 degrees at the discharge point with a dial thermometer stuck in the vent something is wrong. That’s with it on recirculating air, not fresh outside air. Means the air is just coming off the coil which if working well will be about that temperature.

BS. If it is over 80 degrees outside, your Newmar will NOT get down to 40 degrees output. Your dial thermometer needs calibration or replaced. Try the same test with a good digital thermometer. Doug

[MargaretRehkop]

Ver true said. Are things ok?

[imgoin4it]

If I don’t get near 40 degrees at the discharge point with a dial thermometer stuck in the vent something is wrong. That’s with it on recirculating air, not fresh outside air. Means the air is just coming off the coil which if working well will be about that temperature.

[dougrainer]

Can you be specific on the Recall? I see no recall from Winne on Dash AC units. Recalls are safety related. Are you sure you did not have a TSB(Technical Service Bulletin) instead? What was the fault and what was the fix? Did the Dash AC work before the TSB was done? Doug

[dougrainer]

This is a large supplier to the RV industry. Also, your output will NOT be as cold as an Automobile. Doug

http://www.evanstempcon.com/tsg_guidelines.php

1.Park the vehicle and set the engine speed at 1500 RPM.
2.Set the HVAC controls to "MAX A/C", the blower at High-speed, and the temperature control dial to the coldest setting.
3.Visually verify that the A/C compressor clutch is engaged, and the compressor is operating. Verify that the heater coolant valve is closed, and the heater coil tubes are neutral or cool to the touch.
4.The suction hose fitting (at the evaporator outlet) should be cold to the touch. This fitting may sweat or even frost slightly. The liquid hose fitting (at the evaporator inlet) should be warm to the touch.
5.Chilled air should be discharged from the supply louvers in the cab. After 3-5 minutes of A/C operation, the louver air temperature should be approximately 20-30 degrees (F) colder than the warmest air entering the A/C system (fresh or recirculated air).
6.Air inlet/outlet temperature differentials are greatly affected by ambient temperature and relative humidity. In cool ambient conditions, differentials smaller than 30 degrees may be seen. Air can only be chilled to a certain level, and then the A/C compressor will cycle off to prevent evaporator freeze-up. High humidity may also result in smaller differentials; a large amount of cooling capacity is required to dehumidify air, as well as cool it.

[Mandalay_Parr]

Take it to a garage and let a regular AC guy check it out like you would your car.

[MountainAir05]

if you put it in Max Cool and you got those numbers , No it is not working correct. Where is the slider/knob at on the dash. All the way in the blue or just starting in the blue.

[wa8yxm]

The "Is it working or not" is a complex formula in fact it's a whole book of charts. You need to know indoor and outdoor humidity, Intake and outlet temp's both indoors and outdoors and then you either plug 'em into a computer and it says YEA or NAY or you go through one big book of charts.

But I look for delta 30 Delta 20 I'm told is acceptable (Delta is difference between inlet and outlet temps)

[donn0128]

Are you stationary or moving?
It does make a difference.