Is my 8 year old Dometic AC dying?

[RRman]

We're volunteering on a Church Build in Houston TX and at 6PM its 90 outside and 88 inside! Our sole 15K Dometic has always sufficed before... It cools off the RV overnight/by morning and still drips (not frozen). However we are parked on asphalt and door side faces west. Awning is up and we have slide toppers. Air coming out even on dump in the afternoon/evening is not that cool (until AM).
Low on freon/ready to replace??
Advice is appreciated.

 

[racerjoe]

have you checked the intake filter? or the condenser on the roof could be blocked. Or it sprung a leak in the system. I would look at the first two items,

 

[Ozz]

Measure the temperature of the air going into the A/C intake and the air coming out of the diffuser close to the unit.

 

[HOOK-MOC]

You are expecting a lot from one a/c. The asphalt hold heat, evidently you have high humidity, (drip). When it cannot overcome heat, 88 is about as cool as it gets. You may have trouble, yet I'm doubtful at this point because when a leak occurs, it is usually sudden. If you have access to an infrared gun you could learn the exact temp of cooled air.

 

[RRman]

I changed out the AC Filter. Cleaned the outside coils 2 years ago and checked the condenser inside today and it was clean. Now at 9:45PM its 82 outside and 86 inside the living area, but 81 in the smaller front bedroom. We do have all our west facing windows blocked with insulated foil. AC Air coming out is "cool", but not cold. I need to get a probe thermometer, I left mine at home.
My RV is pre-wired for a front AC, but since 07, the rear ducted unit has always kept the bedroom comfortable.

 

[DQDick]

Check the outside coils again, front and back. Spiders, mud daubers and other critters can get in there and clog things up. I check mine or have it checked twice a year.

 

[RRman]

AH, I remembered the Infrared Thermometer in the truck for checking tires/wheel temps.
Farthest Bedroom diffuser is 51 degrees. The Filter/Return underneath the AC is 76. The adjacent "dump" is 50 degrees.
So maybe all is "well" and its just too HOT on this parking lot, but with a breeze and it being 82 outside, why is it still 85 inside?
When my roof was replaced they left off the two attic mushroom vents. I've ordered two and plan to install them, hoping they may provide some attic relief.

 

[cmawendy]

Ours did that in Palm Springs last year and my husband took the hose up top and sprayed it out.......it was blocked with dust etc.....worked like a charm.

 

[Ozz]

quote:Originally posted by RRman

AH, I remembered the Infrared Thermometer in the truck for checking tires/wheel temps.
Farthest Bedroom diffuser is 51 degrees. The Filter/Return underneath the AC is 76. The adjacent "dump" is 50 degrees.
So maybe all is "well" and its just too HOT on this parking lot, but with a breeze and it being 82 outside, why is it still 85 inside?
When my roof was replaced they left off the two attic mushroom vents. I've ordered two and plan to install them, hoping they may provide some attic relief.

Yep, sounds like the heat load. We almost have to have 2 units.

 

[RRman]

Thanks for the advice!
Installed a Coleman (Airexcel) Mach 8 Low Profile 13.5k BTU in the pre-prepared Bedroom Vent. Thanks to my fellow volunteer getting it onto the roof was not so hard, but installing through a builtup/second roof necessitated some big clamps / trouble so the bolts would reach. Air out of the ducted AC is 70. Air out of the new AC is 60.
Will see tomorrow if the RV can stay any cooler than Houston temps.

 

[Ozz]

Super! Good for you, glad you got the unit installed.
You should have around a 20 degree drop between the 'dump' area and the room temperature on A/C units in general.
Good luck down there in the heat.
Ozz

 

[RRman]

Uh-oh,temps were only in the low 80's, now 78 outside and 77-78 inside (Thermostat set to 77)and I suspected the new Bedroom AC was 'carrying the load', so I turned it off and turned down the Thermostat for the ducted unit to 72 degrees but it only blows air 1 degree cooler than the 79/80 degree indoor temp. There was no drippage from the old ducted unit so it hadn't been on for a while. Will let it try to cool the RV down to 75 overnight amd see if there is the usual puddle outside (shows up really well on the asphalt).

 

[Ozz]

quote:Originally posted by RRman

Uh-oh,temps were only in the low 80's, now 78 outside and 77-78 inside (Thermostat set to 77)and I suspected the new Bedroom AC was 'carrying the load', so I turned it off and turned down the Thermostat for the ducted unit to 72 degrees but it only blows air 1 degree cooler than the 79/80 degree indoor temp. There was no drippage from the old ducted unit so it hadn't been on for a while. Will let it try to cool the RV down to 75 overnight amd see if there is the usual puddle outside (shows up really well on the asphalt).

As you know, the unit is not working, it was cooling a bit wasn't it? Can you hear the compressor start a few minutes after the fan starts when calling for cool?

 

[RRman]

I changed the Thermostat to Auto down to 65 at lunchtime as the new Bedroom unit has the living area Thermoter at 72. The legacy AC comes on and blows and clicks once and slightly changes tone after a minute, but doesn't sound as noisy as I recall when the Compressor is running and intake/dump air temps are the same and ambient and there is no dripping so I presume the Compressor is not running...
If it had frozen it had all morning to thaw out.
May be time for a new one... Guess I could have put an ESP to use for resolving this existing AC problem...

 

[Rondo]

We changed our A/C out last year! It was a 2004 unit and as you said just wasn't cooling properly. The tech checked it out and said it was still working but on its last legs. We had him take the old one out(a 13500 unit) and installed a 15000 BTU unit and it is working great. I'm sure yours is a 15000 unit since it is a Big Sky but if not have them put in the bigger BTU unit and you won't be disappointed!

 

[RRman]

Update
Installed a Coleman Mach 8 Low Profile 13.5 K BTU AC in the Bedroom Vent. That kept the RV in the mid to upper 70's during a week of 90ish temps. The Dometic Brisk Air Ducted AC just blew air so it was replaced last night with a Dometic Brisk Air 2 15K BTU Ducted. Brisk Air 2 is a little quieter and definitely putting out cold air. Was a lot cheaper than the new Bedroom AC. Also only 75 pounds

Only installation problem was our thicker (replaced once) roof did not permit the Coleman mounting threaded rods from reaching the AC unit so I had to use 1 small bar clamp and 2 8" clamps to pull it down (compress the gasket) enough to get the rods to start.

Dometic Brisk Air to Brisk Air 2 was an easy swapout, but I had upgraded the control box and thermostat last year which ensured compatability.
Thanks for all the advice!