Air flow on a Coleman Mach III

It is a RVP heat pump. When sitting idle there is a 21 degree difference from the intake to outflow air as measured with a digital laser temp gauge. When traveling, there is only a 6 degree difference. The temps used to be the same whether sitting or driving.

All the RV tech did was to change the fan motor. He did add additional aluminum tape to seal the inside box better.

Unit is 10 years old.

What I really notice is the reduced air flow in the ducts while driving. This is why I asked the original question. I never noticed any difference before.

FYI go easy on tightening the a/c you can squeeze the seal down till it bottoms out the drain pan to the roof. This will stop condensation outside flow and the water will windup inside, blowing around the upper unit....been there done it.

chezhead wrote:
OK. Now that I know that the airflow is correct, why does it not cool well when traveling? It didn't do this before the fan replacement. I found the part shown below just hanging loose. Should it be that way?

I have a FORD. I found this part hanging loose. What is it and is it supposed to be this way? Do you realize how ridiculous my post sounds? WHAT model number and HOW old is the AC? It looks like a mechanical Freeze sensor that is mounted on the copper line on a RVP HEAT PUMP. But, until you give more info, it will be difficult to determine. If it is a freeze sensor, then it would not be the cause of your problem. Also, what do you mean "not cools well"? That is a subjective determination. In Transit, RV's have a natural vacuum that sucks in outside air, which makes cooling a little harder. So, what is the ACTUAL temp difference from the AC unit from sitting still? HOW are you measuring that difference? Doug

OK. Now that I know that the airflow is correct, why does it not cool well when traveling? It didn't do this before the fan replacement. I found the part shown below just hanging loose. Should it be that way?

chezhead wrote:
Which way should the outside air be flowing out of the cover of a Coleman Mach III?

First: If you put the fan in backwards it still moves air the same direction,,, Just not as well, reversing the blades will NOT reverse the air flow. So they put it in right.. Trust me on this or.. Look at a fan and you will understand.. To reverse the blow you have to reverse the direction of rotation. Or put on a different fan.. Read on

My RV tech (And I confirmed this two ways) Says:
Colemans Suck, Dometics Blow.

MOST Air conditioners, both window and RV suck air in from the sides and blow it out through the condenser

Coleman, by design, sucks air in through the condenser and blows it out the sides.

Now: Why is this better?
Well I have had two Carriers (They blow) replaced one by an Advent Air (It blew) and one Coleman (Sucks) IN the past with both the carriers and the advent air when I had to clean the condenser (Which I do have to do once or twice a year at least) the job went like this.. I will use the advent for the first step.

Remove 10 screws (differenet number but still a bunch on carrier)
Remove outer cover

Remove inner cover (Carrier .. More screws, Advent bend tabs straight and cut tape.. NOTE you can only bend those tabs so many times)

Remove fan (My hand is xxxl and won't fit with fan in place)

Remove crud (Clean)

Reassembly is reverse.

Well one day I heard a BOOM and heavy vibration from the Advent so I killed it and found the fan, which is made in China, and looks a bit like a tire and rim was in fact a CHINA BOMB it blew up.

The only fan the dealer had that was the same size was a Coleman.. (It sucks)

So the last time I cleaned the Advent

10 Screws, Lift outer cover, leave inner cover in place, clean and replace outer cover and 10 screws

On the Carrier... 4 Bolts instead of 10 screws.. I DID IT WITH THE A/C RUNNING.

Man is it easier to work on that sucker than on a blower.

Be glad they did it that way.

I am.

Cooling effiency.. IF there is any difference (I doubt) Sucking like Coleman does will have the higher number But as I said. I doubt.

Coleman Mach 3 pull air from the REAR and blow out the SIDES. Doug

no they suck air in to cool the.
I would xheck the mounting bolts make sure they are tight.
What kills the coleman fan motors is they only get air on one side