A/C Compressor Shutting off Mid Cooling Cycle

Also please check this thread about a Coleman Mach.

We've had the 2003 coach, 2002 A/C, since 2009 and used it almost entirely in Florida Heat/Humidity. At 15000, it works hard all day to cool our 31-ft non-slide coach, but it did it and kept plugging away.

Until this summer's Epic Heat Wave. After a few hours of running the compressor'd quit. Amperage was a little high, but I'm reluctant to condemn an $8000 A/C using a $15 Harbor Fright Ammeter. Anyhow, I had cleaned the coils plus the fan and blower wheel, and replaced the filters. What I found, was it would NOT cut out if I ran it with the shroud off. Just came back from a week's trip in hot/humid FL and that trip proved what Chris Bryant showed me in the linked thread: Hot Air was being Re-Circulated, back into the Condenser Coil, by the Shroud NOT having the Foam Baffles.

This was with the MaXXair TuffmaXX aftermarket A/C shroud that's been on this Coleman Mach 15 all those years since we got it in 2009. So, in addition to Cleaning (BOTH Coils, remove the Top Front Sheet Metal) and Filters, I'd suggest making sure the Shroud isn't catching some of the outdoor discharge, hot air, and sending it back to the Condenser Coil.

I'd thought air is drawn into the Shroud from the Sides, then blown Out, Rearward, through the Condenser. NOT SO. It's Pulled IN, From the Rear, then escapes through the sides of the Shroud. So, we need to block any hot air from turning the two rear corners of the unit, back around to the face of the Condenser.

You likely have an OEM Coleman shroud. It isn't clear to me whether they need the foam baffles or not. I think I read where TuffmaXX wants you to remove OEM foam and add theirs. In any event, I'd baffle the thing. I had a swim noodle and it fit. My original plan was the foam insulation that slides over copper pipe in an attic.

Another thing I've learned, is that an aging compressor(let's call it a "maturing compressor" since it still has useful life) will draw a little more amps than a new one. This can show up in heat. Also, run capacitor, and start assist device wearing out sooner than new.

Here is Chris Bryant's A/C Tuneup Blog Post. There are links to pictures, but I'm not sure they all work.

From Chris' Site, here's a diagram. In our case, the airflow over the Condenser (the RED Coil) is backwards from the diagram. The sheet metal you need to take off to clean the Evaporator Coil is to the left of the Blue Coil. You don't need to take the sides off, just the top and downward sloping parts.

The control board info aligns with personal experience. But I wonder about my little 5K Goldstars - they restart in under a minute with less than max head pressure. Fascinating.

If there is no problem with the compressor (and it sounds like it is) then a hard start capacitor which helps with that inrush current.

I would look at the outside coils though- severely clogged coils could keep the pressure high. I've seen that happen quick with Cottonwood seeds.

MEXICOWANDERER wrote:
Like the fan motor in a Fantastic Fan. $65.00 Entire fan $72.00

Dougrainer, is there a "specified time frame" for this type of compressor to bleed off high head pressure? I realize it's temperature dependent.

The Control boards have a 2 minute 45 second delay which is more than enough to allow the head pressure to equalize. Doug

One easy thing to try first is replace the run cap, if it isn't up to specs and the compressor is running at full load it can cause over current.

Denny

Like the fan motor in a Fantastic Fan. $65.00 Entire fan $72.00

Dougrainer, is there a "specified time frame" for this type of compressor to bleed off high head pressure? I realize it's temperature dependent.

j.robinson389 wrote:
And I am guessing the compressors in RV units are not serviceable?

No, they are not. It would cost as much to replace the compressor as buying a new upper unit. Doug

And I am guessing the compressors in RV units are not serviceable?

It is not the voltage when the compressor is running.

It is the voltage when the compressor motor needs a jock strap trying to start against high head pressure.

Therefore what is "that" voltage, then.

This is a comment dealing with voltage and motors not dealing with how the AC works. Douggrainer is absolutely right on the button - my comment deals with when to measure voltage (on motor starting).

Many high BTU commercial and all motor vehicle A/C compressors use magnetic clutches. Other than cheapskating the roof air whats the harm in letting the motor spin-up before engaging a magnetic clutch? This allows the condenser and evaporator fan to spin up before the compressor load is applied.