A/C help needed. Coleman mach 8 .. Quartzsite

[groundhogy]

I was away and got a text that the a/c was no longer working.
I came home to the RV about an hour or more later. The two interior fan speeds work. When i switched to a/c, I think I heard the compressor come on.

So I climbed up, and pulled the wires off the capacitor. Discharged it. Measured like 5-6 Mohms... and climbing i think i remember.

Then I measured the compressor...
C-S 5.5 ohms
C-R 1.3 ohms
S-R 6.2 ohms

But now I remember, the black wire from the compressor was still connected to the board. Was the black the common? Maybe it made no difference if it was just grounded?

So I put it back together, and it seemed to run for a few hours, but It wasn’t making cold really well. So I was thinking, maybe it needs coolant. It has a port installed and was charged at the beginning of the summer.

Then, a little while ago, it kind of cycled off, but in a weird way that drew my attention. Maybe it made a different sound than normal. Nothing dramatic as far as a sound that I can report here.
But i turned thermostat knob to very warm to just let fan run for awhile.
Then after about 10 min, turned it cooler and cooler, but nothing happened. I didn’t hear any attempt at compressor turn on.
Then I left thermostat at very cold setting and went to fan only for awhile. Came back to a/c .. nothing.

What should I do now?

[groundhogy]

This installer had one guy at the top. One guy at the bottom of the ladder.
Extension ladder tilted onto the RV.
Rope with hook (onto some feature of the A/C that i couldn’t see.).
Slide A/C down ladder to ground person.

[dougrainer]

deltabravo wrote:
The hardest part of replacing the A/C is getting the new one up on the roof, and getting the old one off the roof.

I did it a few years ago when I switched to a Mach 8 heat pump

Yes, that is a great way to do that. But, try that with a Metal Airstream:B You can do it, but be very careful. This is what our shop uses(not this brand), and have for 35 years. The one we use is about $1400, but is easily broken done at center to load in a pick up truck for mobile use. IF I decided to do mobile RV service, this is one tool I would have. It would pay for itself in a few months. Doug

https://images.app.goo.gl/N2JiaLYYSQTwQ2fs7

[deltabravo]

The hardest part of replacing the A/C is getting the new one up on the roof, and getting the old one off the roof.

I did it a few years ago when I switched to a Mach 8 heat pump

[dougrainer]

groundhogy wrote:
Yes, the mach 15 fan is quiet , but also the compressor sound is quiet.
You listen for the compressor sound when you want to see if it’s actually on.

The tech was not approving of dometic penguins (their low profile offering?). He said he has a small pile of them at his home base that are broken and he said like 3 years old.

The newer style Penguins that had 410, Airstream had a problem caused by installers at Airstream. They were bolted from the top down and when they manhandled the Penguins on top to mount(they had to remove the top shrouds), they were pushing the Copper lines against each other and the normal vibration of running caused the line to rupture and leak coolant. Dometic replaced hundreds if not thousands of those Penguins on Airstreams for a few years until Dometic found out what was happening. Dometic then installed rubber bushings around the copper lines at areas that could be pushed to prevent this. Also, the original Penguins that had 410, the compressors run at higher PSI due to 410 and the first compressors had a high failure rate, which Dometic replaced the design of the compressor's once they realized that problem. The Penguins built in the past 2 or 3 years, are just as reliable as ever. Doug

PS, the original Mach 15 also had a high failure rate due to the design of the separate Condenser fan system. The motor mount bolts would break off and the fan would fall over and sometimes shear the regular condenser. This is the reason they redesigned that system and it is quieter now.

[groundhogy]

Yes, the mach 15 fan is quiet , but also the compressor sound is quiet.
You listen for the compressor sound when you want to see if it’s actually on.

The tech was not approving of dometic penguins (their low profile offering?). He said he has a small pile of them at his home base that are broken and he said like 3 years old.

[dougrainer]

groundhogy wrote:
The new a/c is a Coleman mach 15.
It is called a 15kbtu, but i think i saw on a lable it listed as a 14.5k.
The last a/c was a 13.5k mach 8 low profile.
I can report these observations.

Cooling: Not a dramatic difference although the mach 15 seems better. Mach 15 a simpler design. The Mach 8 literature says it is a more efficient design i think because they separatet air moving with 2 fans. Allows condenser fan to run full anytime its desired? So maybe at 13.5k and more efficient, it approaches a standard a/c at 14.5k? Idk.

Compressor quietness: When the two techs came inside to do the first turn-on, they thought the mach 15 wasn’t working. Thats how quiet the compressor is. I assume compressor vibration is low also. The mach 8 compessor was louder and wiggled alot. I think this caused/assisted the eventual copper tube rupture.

Note that the above may not hold for all purchases for all time as the mfr may use several different compressor brands on their factory line.

Your new model the Condenser fan runs ANYTIME the compressor runs. Yes, it is quiet. Funny thing is, the original 15, the Condenser fan system sounded like a jet engine. RVP redesigned the fan blade and Condenser motor system to be quiet like you have now. Doug

PS, you must have a OLD Airstream to have a factory installed RVP AC unit. A/S has used Dometic for almost 20 years now.

[groundhogy]

The new a/c is a Coleman mach 15.
It is called a 15kbtu, but i think i saw on a lable it listed as a 14.5k.
The last a/c was a 13.5k mach 8 low profile.
I can report these observations.

Cooling: Not a dramatic difference although the mach 15 seems better. Mach 15 a simpler design. The Mach 8 literature says it is a more efficient design i think because they separatet air moving with 2 fans. Allows condenser fan to run full anytime its desired? So maybe at 13.5k and more efficient, it approaches a standard a/c at 14.5k? Idk.

Compressor quietness: When the two techs came inside to do the first turn-on, they thought the mach 15 wasn’t working. Thats how quiet the compressor is. I assume compressor vibration is low also. The mach 8 compessor was louder and wiggled alot. I think this caused/assisted the eventual copper tube rupture.

Note that the above may not hold for all purchases for all time as the mfr may use several different compressor brands on their factory line.

[sayoung]

garyemunson wrote:
If someone put a charging port on it in the past, sounds to me like it's time for a new A/C.

If OP had it charged then it's got a hole somewhere. Get that fixed or replace the unit. Those compressors need the proper amount of returning gas on the suction line to cool it.

[time2roll]

I would have a new high efficiency unit installed. This thing is done.

[groundhogy]

Bad Design:
Having that long soft copper tube hanging out there and wiggling like that IS a bad design.
I am not a mechanical engineer and it totally captured my attention.
On the other hand, I’m not sure how the engineer would cheaply address that. Maybe put lead tape on the compressor to limit wiggle? The compressor mounts on rubber.
Its the compressor people that should be reducing the wiggle on their product. Tecumseh is mfr.

[groundhogy]

I have an airstream currently with the low profile ac on top.
There is an ac shortage going on. The tech can only get a regular 15k coleman right now.

I ordered an easy start.
Oh, if anybody wants to order one, you can get $40 off right now.
Use coupon code AIRSTREAM

[groundhogy]

Ok. Tech was just up on top.
I am not at the RV (Parker).

He found a tube rupture. I did not see this last night, so I am assuming that after I climbed down and restarted the unit, the leak opened up.

My theory at this time..
I was up there last summer when the leak first showed up. At the time i noticed that that compressor wiggled like hell. I was immediately concerned for the long copper tube comming out of the wiggling compressor.
I think the original leak was in that wiggling tube, maybe right near the compressor. And as the unit put up hours, that section became more and more work hardened and brittle. Finally resulting in rupture.

What do you think?

[C_Schomer]

I missed that it has a tap valve... not a good sign. It's also not good to be putting refrigerant into the low side without seeing what the high side is doing. Occasionally, a restricted drier, if it even has one, or restricted cap tube will starve the evap, so only going by the low side reading is bad. IF it leaks on the low side and goes into a vacuum air will be sucked in and it ends up in the condenser and raises head pressure. Craig

[groundhogy]

No. It is a pretty slow leak.
It was charged in the very beginning of the summer. So it has almost made it through the whole summer.

I originally put the port on. If you put one on yours, be careful. The gaskets on mine were put on so haphazardly, it would have certainly leaked. I pulled the gaskets, cleaned and reseated them with some automotive gasket dressings, etc.