[77newell]

Tom: could you clarify the "working 1/3 as good". Did that mean when it was working it put out 1/3 the cooling, or that it worked 1/3 of the time it was needed?

[Fulltiming]

A previous owner had converted mine to 134A. Mine worked very rarely and when it did the air flow was not sufficient to really allow it to cool the front area well. I had a slow leak so it seemed every time I tried to use it, it was low on refrigerant. After recharging it, the air would blow cold then start warming up after a day or two. Newell told me to just run the generator and use the basement airs, it would be less expensive and work better. I suspect that the very long refrigerant lines, the relatively small AC compressor on the engine and the location of the evaporator all worked against it. I would not doubt that on my coach, it would cost thousands of dollars to make it reliable, ie replacing the compressor the evaporator, the expansion valve and the refrigerant lines. With both front airs on when driving, I really don't need the dash air. I use the dash air fans on vent to circulate the air and all is good. I can easily get too cold up front driving during the summer if I am not careful as the drivers side basement air blows down the valence panel and directly onto the driver.

[Brad Townsend]

So did you remove the belts from the compressor so as to not have the added burden of the engine running something not needed?

[Fulltiming]

Not at this point. I probably should have but I doubt the drag with compressor clutch off is much.

[encantotom]

Jon. Just raw cooling btus. I can get cold from the dash air conditioning in my02. Not at all in my 90

Tom

[77newell]

The temperature in the "cockpit" will depend on the relationship of two things; the amount of incoming heat and the amount of cooling being applied. This is important because we have some control over both parts: the heat input and the cooling that takes the heat away.

The heat input comes from air leaking into the area, the radiation coming through the glass and the conduction coming through the various surfaces. On my 93 coach the heating has struggled to keep up, I suspect if the A/C was operational it would too. One of the main factors I found was that the coach leaks a lot of outside air and sealing those leaks is difficult because of access to some of the leaking points. Unless leakage can be limited I can't imagine either a heater or A/C keeping up.

I closed up the coach, turned on both the roof fan on high and the exhaust fan for the stove. I then walked around with an incense stick smoking scanning for incoming air. My entry door, since then rebuilt, and the area where the large heat hoses come through the floor were the big culprits and improvements have been made. I thought the sliding windows would be a big deal, according to my test they weren't. A better test would be to travel at highway speed and have someone walk scanning for leaks. Since I'm solo I have not been able to do this better test.

Since coach glass has gotten bigger with newer coaches I don't imagine that as the difference between the performance of newer versus older coaches.

Looking at the size of my engine driven air conditioning compressor I would imagine that it should put out at least 30,000BTU/Hr when operating at max capability. However, the condenser coil looks only marginally larger than my 13,000BTU/Hr house A/C condensers. Since the Freon is different it is hard for me to calculate all the various possibilities other than to say there should be noticeable cooling showing up. I do know that the 77 coach I had had only roof air for cooling the cockpit and seemed to do a decent job at 13,000BTU?Hr. So, if our engine driven cooling system is working well we should be able to feel significant cooling, just on the basis of the comparison to what happens when we use roof air.

So, if you have a front roof air, what happens when it is used instead of dash air. In this comparison all the variables except the source of the cooling is the same. If the cockpit is cooler with the house air running one compressor then there is a problem with the dash air. If a single house compressor supplying the cockpit area produces essentially the same result result as dash air then I would go on the search for air leaks.

One thing to note; the temperature of the air felt where it discharges is only a partial measure of effectiveness of the system. It is the temperature difference between the air inlet to the system and the air outlets that is the measure of the performance of the system. a typical delta T is 20 degrees. My heating feels barely warm at times, but when the inlet temp is below freezing that is reasonable. Unfortunately, we don't know the air flow CFM through these systems. If we did we could combine that with the delta T and calculate the BTU/Hr performance and know how well it's working. I wish .....

I hope this helps