| roof ac question [message #95890] |
Sun, 15 August 2010 03:13  |
deanandcheriek
Messages: 67
Registered: March 2007
Location: portage IN
Karma: 0
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When SunnyB is plugged into shore her ColemanTRS roof air will run you out the door with a what seems like an arctic blast of continuous cold air even in the non-stop 90 degree weather we've been having but when we have to run the air with the generator- not moving it's alittle more than cool- going down the road forget it, barely cool. We do have her original 4K Onan that fires right up and runs great. So is this just a quirk of the Coleman or the Onan? Any info will be greatly appreciated. Thankyou 
Dean&CherieK PortageIN & OrrMN '73 23'PD "SunnyBeaches"
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| Re: roof ac question [message #95891 is a reply to message #95890] |
Sun, 15 August 2010 05:44  |
Rusty
Messages: 197
Registered: October 2005
Location: Philadelphia Pa
Karma: 0
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On first thought I would say, the coach is not moving when on shore power, so no air is being exchanged by movement down the road i.e. as if you had windows open or something .
2nd, check the AC current draw in both configurations. Easy enough to do, with one of those multi-meters that look like they have a 'hook' on them. You use the hook to clamp onto one of the two wires (the hot side) sourcing the 120v a/c to the unit.
On the Onan probably in the back you will find the two thick wires coming out of it that provide the generator output power. I'm not sure if it matters if you choose one wire or the other, but clamp the meter around only one. Start the generator and power up the a/c unit. Wait until its compressor kicks in and the air is coming out cold. Read on the meter the amount of current being transferred, should be around 20 amps. If its not close to that, theres your problem, the Onan is not sourcing enough power.
Stop the unit, kill the generator. Go buy a new extension cord, as short as you can. About a few feet from the female end that you will plug onto the coach, strip about 8" of the insulation off the extension cord, so the black, white and green wires themselves are exposed. Hook the meter around only the white wire. Plug the extension cord onto the coach. Then, plug the other end into shore power. Fire up the a/c unit. You should see about 20 amps.
Just my two sense. Someone else may have a better way to diagnose this.
Rusty
75 Glenbrook
Philadelphia Pa
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| Re: [GMCnet] roof ac question [message #95896 is a reply to message #95891] |
Sun, 15 August 2010 07:32 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Rusty's method will certainly work, but is more difficult than necessary.
If there is a difference in current draw between the two power sources, it
will be because of, or reflected by, the voltage. And since the A/C will
be, by far, the largest current user, the entire coach system will reflect
any voltage change.
With only the A/C ON, just use a multimeter (or a plug-in line voltmeter) to
check the voltage at any wall socket in the coach, first while the A/C is
running on shore power, then on the Onan.
Chances are you'll find the Onan's output voltage to be low. Easy detailed
instructions for adjusting that voltage, using only the voltmeter, are in
the Onan manual.
Ken H.
On Sun, Aug 15, 2010 at 6:44 AM, Rusty <gmc@bauerlein.com> wrote:
>
> 2nd, check the AC current draw in both configurations. Easy enough to do,
> with one of those multi-meters that look like they have a 'hook' on them.
> You use the hook to clamp onto one of the two wires (the hot side) sourcing
> the 120v a/c to the unit.
> ...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] roof ac question [message #95901 is a reply to message #95890] |
Sun, 15 August 2010 08:08 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Dean,
Rusty has provided good advice for testing.
You indicated that you have the Coleman TRS unit and that appears to
be an 13500 BTU cooling capacity unit. It should show about a 14 amp
draw under load with a spike at compressor startup. It is possible
that your 4K onan is not providing enough power to run the AC
effectively. It may have low voltage along with not enough amp
capacity.
The test equipment that you could use to evaluate your problem could
include the following.
Digital clamp Ampmeter/Multimeter:
This one is your best bang for your buck.
http://www.harborfreight.com/general-merch/electrical/digital-clamp-on-multimeter-95652.html
Voltmeter:
I recommend this for your coach as it plugs into a wall socket and you
can monitor your line and generator power output.
http://www.campingworld.com/shopping/item/ac-voltage-meter/29375
Good Test meter but not to be used to measure amp load:
http://www.harborfreight.com/7-function-digital-multimeter-92020.html
J.R. Wright
GMC GreatLaker
TZE Zone Restorations
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan
>
> When SunnyB is plugged into shore her ColemanTRS roof air will run
> you out the door with a what seems like an arctic blast of
> continuous cold air even in the non-stop 90 degree weather we've
> been having but when we have to run the air with the generator- not
> moving it's alittle more than cool- going down the road forget it,
> barely cool. We do have her original 4K Onan that fires right up and
> runs great. So is this just a quirk of the Coleman or the Onan? Any
> info will be greatly appreciated. Thankyou :d
> --
> Dean&CherieK PortageIN & OrrMN '73 23'PD "SunnyBeaches"
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] roof ac question [message #95902 is a reply to message #95890] |
Sun, 15 August 2010 08:26 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Aug 15, 2010, at 2:13 AM, cheriek wrote:
>
>
> When SunnyB is plugged into shore her ColemanTRS roof air will run you out the door with a what seems like an arctic blast of continuous cold air even in the non-stop 90 degree weather we've been having but when we have to run the air with the generator- not moving it's alittle more than cool- going down the road forget it, barely cool. We do have her original 4K Onan that fires right up and runs great. So is this just a quirk of the Coleman or the Onan? Any info will be greatly appreciated. Thankyou :d
>
Your air conditioner should run the same from either the land line or from your Onan.
It is likely that your Onan is not adjusted properly and is putting out too low a voltage.
First turn off all major electrical appliances. Air Conditioner, electric water heater, etc. and unplug your converter (battery charger.)
Then pull out your Onan and start it. First make sure that it is running well -- adjust the high speed jet (located at the bottom side of the carb bowl) until it runs the best. The initial setting is 1-1/2 turns. Let the Onan warm up and run for about 10 minutes.
Check the voltage. I use a simple plug in meter. I run an extension cord out a window so that I can read the voltage while working right at the Onan.
Set the voltage with no load on the Onan to 128 volts. You set the voltage by adjusting the speed by turning the nut at the end of the governor spring located on the top of the engine. After you get it to 128 volts, go inside and turn on the air conditioner. Again check your voltage. it should now be at least 120 volts. It will not harm the air conditioner to run at higher volts such as 124 or so. It will hurt it to run at low voltage (below about 110).
With my 6000 K Onan I can run the air conditioner, water heater, battery charger, and the microwave all at the same time and still get voltage in the area of 118 to 120 volts.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: roof ac question [message #95998 is a reply to message #95890] |
Mon, 16 August 2010 01:10 |
deanandcheriek
Messages: 67
Registered: March 2007
Location: portage IN
Karma: 0
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this is what I love about belonging to the "GMC cult". Info, info, info. Dean hasn't had the time to use all the "info" yet but I want to thank you all for helping out anyways.
Dean&CherieK PortageIN & OrrMN '73 23'PD "SunnyBeaches"
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