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Carrier AC Replacement


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2010 HR Neptune 37PBQ

The rear AC unit is no longer cooling...interior fan functions but compressor "stumbles" repeatedly when trying to start up and no cooling.  Removed the capacitor and it tested "OK" so assume the unit is ready for the scrap heap.   Looking for the best approach to replace at least the rear unit and probably do the front as well since it is the same vintage.  About 2-3 years ago there was info on a Coleman cooling/heating unit that was supposed to work with the existing Carrier remote control unit as long as the Coleman adaptor plate was installed.  Part numbers were 47004B876 (roof unit) and 8530A5221 (adaptor plate).  Since the Carrier controls both the AC and the furnace, the replacement should function in the same manner.  Any newer info and direction from the group regarding this potentially expensive repair?

Adam

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Posted (edited)
3 hours ago, lake49068 said:

Removed the capacitor and it tested "OK" so assume the unit is ready for the scrap heap. 

"The Capacitor" statement indicates you checked ONE capacitor whereas there should be a PTCR, a Compressor Start Capacitor with variable microfarad rating and a Compressor/ Fan Run capacitor with 3 terminals which is probably the one you checked.  You need to use a meter which you may have done.

I thought my rear A/C was going to kick my patoot  today.  The compressor shut off in the middle of the night after making some loud noises.  It turned out the fan run capacitor was intermittent.  It checked good with a meter 2 times but eventually it showed 0 Mfd after I put a new one in and was wiggling the capacitor terminals.  The fan would run fine but then slow down causing the compressor pressures to increase until it shut down.  The part that took me some time was realizing the fan speed would change as the capacitor was changing value.

Keep at it, your A/C is probably in good shape other than a minor part.

Edited by Hypoxia
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Your 2010 Neptune would have been built during the Navistar ownership instead of legacy Monaco Coach Corp.  However, Monaco used Dometic A/C systems with Dometic thermostats and even the 2010 Dynasty used Dometic.  

Are you sure your coach has Coleman A/C units?

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And if not the run capacitor it could be a slow leak allowing the unit to start but not maintain low side pressure.  If that's the case a good AC tech can find the leak, seal it, add a port and add refrigerant.  90% of the techs won't go to that much trouble, they'll convince you to scrap the unit and buy new (not much mark-up in soldering leaks).  A new unit means more hours for him + more commission on parts.  Cha-ching!

- bob

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Yup, it sure is a Carrier unit!  The installed capacitor which checked "OK" is a "start/run" and the only other component that may need to function in the parts breakdown is item #32, a "start thermistor" that I didn't remove or check out.  Not sure what it does or if it is important to the startup problem.  There are no other capacitors shown in the parts breakdown or found when I opened the unit up.  And the AC unit is at that "suspect age" so dealing with leaks is not high on my list...want a long term solution rather than a stopgap.  However, if there are any thoughts about the "start thermistor", please post!

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Posted (edited)
1 hour ago, lake49068 said:

 However, if there are any thoughts about the "start thermistor", please post!

PTCR It won't start without it.  Find it, smell it, they normally smell burnt when bad. PTCR

There is no age to expect to replace an A/C unit.  I have a bunch on stick houses 20-29 years old working fine.  Most of my major problems have been with the newer R410 units which were all installed while I was travelling and not available to see the real problem ($$$ Profit).

Edited by Hypoxia
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  • 5 weeks later...

The PTCR does not stink and I'm ready to get serious about replacing the Carriers.  Veurinks just quoted Dometic units complete with new thermostats, wiring and lots of labor so think they're on the wrong track...expect an update from them early next.  What I need is more current information about the "most logical" Coleman unit that utilizes the Carrier remote.  The remote controls not only the heat/cool of the roof top unit but the propane heat and should be the way to go...if available.  Anyone do a similar Carrier replacement lately?

Adam

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