A/C Issues

[Rey&Reina]

Last week my son and I did a quick overnight trip to Lion Country Safari and the next morning, after running the A/C all night, my coach was only down to 77 degrees while it was 81 degrees out.


I was told to check the temp of the air in vs out to start to figure out the problem so I a purchased an infra red temperature sensor. I tested it today an the air intake was about 85, the cooled air was only 76. So the return air is colder but not nearly the 15-20 degrees difference. I would assume if I had had refrigerant leak it would would all leak out.


Anyone have this problem or know what I should start to look at next. Being a long weekend, no one is open until Tuesday but I would like to try to rule some things out. I took the cover off and the coils are fine and everything looks good.



Thanks in advance for any ideas.

[Lt Keefer]

I don't know what it's called, but their is a thing on the rooftop coil that can be moved to improve performance of the system. It is a thermistor or some such thing, I'm sure one of the experts will chime in and set us straight.

[Trkyte@msn.com]

Common problem is the partition between the intake and exhaust falls down because it is only a friction fit.
If you removed the cover you should have seen it.

With the cover removed you can see the thermistor he was talking about. It is a wire pushed into the fins of the evaporator. It’s there to detect ice buildup.
Pull it out of the fins and just let it hang. Then see what your temp difference is.

If this helps, run the unit and, with the thermometer find the warmest spot on the fins and insert it there

[Rey&Reina]

Part of what I did today while giving the unit some time to cool down was to get some foil tape and I taped up the divider and also streamlined the path of air into the ducts. I was hoping the divider was the problem but after I finished taping it up, I still wasn't getting a huge difference in temps.



I will try removing that part from the coils and see if that works.


What I find promising is that it I do get some cold air.


Thanks!

[twovillagers]

Originally Posted by Rey&Reina

Part of what I did today while giving the unit some time to cool down was to get some foil tape and I taped up the divider and also streamlined the path of air into the ducts. I was hoping the divider was the problem but after I finished taping it up, I still wasn't getting a huge difference in temps.



I will try removing that part from the coils and see if that works.


What I find promising is that it I do get some cold air.


Thanks!

I have a Thor Vegas 24.1. From reading this forum and talking to friends that have motorhomes (Tiffin and Renegade), nearly everyone has problems cooling their coach in full sun on hot days, especially 90 degrees plus.

There are some changes that each provide incremental improvement:

--For lowering heat after driving, I added heavy rubber backed carpet mat in cab area and added insulation everywhere I could access. That includes way up under the dash, under the writing desk area, and especially under the "dog house". All of this lowers the effect of engine heat and engine/road noise. Lots of postings on this subject.

--Bought exterior Sun Shades for windshield and side cab windows.

--Slightly relocated the divider between air intake and outlets to fit properly and taped seams with foil tape.

--As one poster noted, in the Vegas/Axis the styrofoam air channels or "ducts" continue beyond the front ceiling vents to who knows where. I blocked that continuation with self stick insulation. This was an easy and very worthwhile change.

--I let the coach cool down more than normal in the morning to help some in the afternoon. I also run the coach A/C and generator when driving on hot days.

--Buy a small oscillating fan to help circulate air.

--There has been major discussion on moving the thermistor and or letting it hang in the intake air. If your compressor is cycling frequently while your thermostat is still "calling" for cold, it may be the fix that will help. In my case, it had no effect, but it's worth a try, easily reversible and quick.

I just checked my intake/vent temperature differential with a laser gun and it was about 25-27 degrees. This was on an 80 degree morning with the coach under cover. I have never had less than 20 even when the roof is in full sun. If you're getting much less than 18-20, it's worth having a tech check it out. The 9 degrees you noted is way out of spec.

In my opinion, the root causes of inadequate cooling are far too little roof and wall insulation and a lot of single pane glass. All of the changes/additions above will have some effect, but the "fix" for some climates, and those seeking perfection, is adding a second A/C unit. I'm not yet dissatisfied enough to go that route.

[Beau388]

Originally Posted by twovillagers

I have a Thor Vegas 24.1. From reading this forum and talking to friends that have motorhomes (Tiffin and Renegade), nearly everyone has problems cooling their coach in full sun on hot days, especially 90 degrees plus.

There are some changes that each provide incremental improvement:

--For lowering heat after driving, I added heavy rubber backed carpet mat in cab area and added insulation everywhere I could access. That includes way up under the dash, under the writing desk area, and especially under the "dog house". All of this lowers the effect of engine heat and engine/road noise. Lots of postings on this subject.

--Bought exterior Sun Shades for windshield and side cab windows.

--Slightly relocated the divider between air intake and outlets to fit properly and taped seams with foil tape.

--As one poster noted, in the Vegas/Axis the styrofoam air channels or "ducts" continue beyond the front ceiling vents to who knows where. I blocked that continuation with self stick insulation. This was an easy and very worthwhile change.

--I let the coach cool down more than normal in the morning to help some in the afternoon. I also run the coach A/C and generator when driving on hot days.

--Buy a small oscillating fan to help circulate air.

--There has been major discussion on moving the thermistor and or letting it hang in the intake air. If your compressor is cycling frequently while your thermostat is still "calling" for cold, it may be the fix that will help. In my case, it had no effect, but it's worth a try, easily reversible and quick.

I just checked my intake/vent temperature differential with a laser gun and it was about 25-27 degrees. This was on an 80 degree morning with the coach under cover. I have never had less than 20 even when the roof is in full sun. If you're getting much less than 18-20, it's worth having a tech check it out. The 9 degrees you noted is way out of spec.

In my opinion, the root causes of inadequate cooling are far too little roof and wall insulation and a lot of single pane glass. All of the changes/additions above will have some effect, but the "fix" for some climates, and those seeking perfection, is adding a second A/C unit. I'm not yet dissatisfied enough to go that route.

For class A coaches the biggest heat loss/gain it through the windshield. The cheap answer a curtain or Reflextix covering the windshield. It is even better to put the sun shield on the outside of the windshield. Although Magne Shade is expensive, I think it is the best solution, plus you can still see your beautiful view of the countryside. Magne Shade is also available for the cab's side windows.

I could not keep my hurricane 31S cool in the direct sun on a 100 degree day with all the windows and windshield covered with Reflectix with the one Coleman mach 15 A/C. About 88 degrees was the best I could do at 4 pm in the afternoon. With a second A/C and Magne Shade, both A/C compressors cycle on a 100 degree when the digital thermostat is set at 75 degrees. The front of the coach will get much hotter than the bedroom unless I shutoff all but one of the bedroom ceiling vents and run the defroster fans on low to keep the front of the coach cooler.

[Pete'sMH]

Other thing that will help is to pull in your slides during the heat of the day if you can.