Roof AC cool but not cold

[JOglesby]

We got out Bullet 290BHS about 11 months ago. We have used it a handful of times. Mostly in cooler weather. Took it out this weekend and the bedroom AC blows pretty cold pretty quick. The main AC just doesn't seem to get cold. It's blowing cool but not cold air. Outside Temps are high of 80 and overnight low was 60.
Could it be low on freon? Do you add it just like a house AC?

[JRTJH]

There's no maintenance on the freon system in today's RV rooftop units. If it's leaking, refill it and it'll leak again, and with no way to stop the leak, the "environmental damage to the atmosphere" continues....

So, replacement of the top unit is the solution to a "leaking or low freon condition"... Most OEM air conditioners are warrantied for 2 years, but the sooner you get it to a repair center, the sooner they can get a replacement on order. Last I heard, Coleman and Dometic were backordered on replacement units, so the sooner the better.....

You don't have to use a RV dealer, any "authorized repair center" for your brand air conditioner can get the ball rolling.

[wiredgeorge]

Won't a repair center put a device into the A/C outlet to measure the temperature? The cabin area is quite a bit larger than the bedroom so may not feel as cold/cool as the smaller area.

[JOglesby]

I've put a thermometer at the outlets and they are significantly different. Bedroom reads about 63 and the main is only about 72 at best. We are in a place where yes its sunny but only about 79 - 80 outside and gets about 72 inside. I'm concerned because we are headed to central Florida next month for 2 weeks. Gonna be hot.

[Badbart56]

The RV repair facility that did my silicon roof six years ago advised that they could modify the A/C units so that they could be serviced like an auto or home unit. I think the cost at the time was two or three hundred dollars. Others may also offer this service.

[chuckster57]

Originally Posted by JOglesby

I've put a thermometer at the outlets and they are significantly different. Bedroom reads about 63 and the main is only about 72 at best. We are in a place where yes its sunny but only about 79 - 80 outside and gets about 72 inside. I'm concerned because we are headed to central Florida next month for 2 weeks. Gonna be hot.

Test is temp drop from return to exhaust. At 20 degrees is considered good. If your not getting it at the warm AC make sure the divider is intact and sealed.

Originally Posted by Badbart56

The RV repair facility that did my silicon roof six years ago advised that they could modify the A/C units so that they could be serviced like an auto or home unit. I think the cost at the time was two or three hundred dollars. Others may also offer this service.

I havent seen anybody do it with sucess.

[jsb5717]

Could it be other things, like a collapsed duct or return intake (if it's the whisper quiet type)? If air flow is restricted on warm days then the duct can get heated before expelling the air. I don't know what the temp differential might be with restricted flow...just thinking out loud. I'd be temped to run a borescope through to make sure all is well.

FWIW, I had to open up our whisper quiet return ducts to increase air flow.

[wiredgeorge]

There are many things that should have been done at the factory that don't seem to get done. I have a 28' fifth wheel and a 15K BTU A/C won't keep us cool in triple digit Texas sun. I have re-sealed all the air ducts and air outlets with HVAC foil tape. I have installed very dark window tint. The one thing that made the most difference is I installed a gizmo from RV Airflow. This thing basically closes off the quick cool feature on my Dometic Brisk II A/C and forces air into the ductwork. It made a big difference on airflow. (I also use a 14.5K btu portable A/C to augment the roof top unit) and our camper stays in the mid-70s in triple digit direct sunlight. Try searching for ways to improve your camper's cooling; there are a lot of threads on this forum.

https://rvairflow.com/

[jasin1]

Could be a lot of things ….dirty condenser coil ..low on refrigerant…is the compressor running? ..no ?..bad capacitor possibly

They are not very sophisticated ac systems, on par with a window unit…you can add access ports. But you have to recover the refrigerant …braze in the fittings..just standard refrigerant Schraeder fittings… should add or replace the filter drier…r410a is about $25 a pound wholesale .. it’s only a few pounds in there I imagine ….but you have to find the leak (if it’s leaking out)

If it’s a few year old ac unit then it’s probably a cracked braze joint at a fitting…if it’s a 10 year old unit it could have pin holes in the evap coil ( can’t fix not worth replacing coil )…need to have a vacuum pump and a set of gauges…a good third year ac tech that likes to solve problems and is your friend would probably fix it for material cost and a 12 pack of beer. Just for the challenge of it

[wiredgeorge]

Originally Posted by jasin1

Could be a lot of things ….dirty condenser coil ..low on refrigerant…is the compressor running? ..no ?..bad capacitor possibly

They are not very sophisticated ac systems, on par with a window unit…you can add access ports. But you have to recover the refrigerant …braze in the fittings..just standard refrigerant Schraeder fittings… should add or replace the filter drier…r410a is about $25 a pound wholesale .. it’s only a few pounds in there I imagine ….but you have to find the leak (if it’s leaking out)

If it’s a few year old ac unit then it’s probably a cracked braze joint at a fitting…if it’s a 10 year old unit it could have pin holes in the evap coil ( can’t fix not worth replacing coil )…need to have a vacuum pump and a set of gauges…a good third year ac tech that likes to solve problems and is your friend would probably fix it for material cost no a 12 pack of beer. Just for the challenge of it

If he is seeing cold air on the inside of his camper, I suspect the compressor is running and the capacitor is good. It is just as likely he is loosing cooling as the lower unit doesn't have good seals with HVAC tape.

[jasin1]

Originally Posted by wiredgeorge

If he is seeing cold air on the inside of his camper, I suspect the compressor is running and the capacitor is good. It is just as likely he is loosing cooling as the lower unit doesn't have good seals with HVAC tape.

Yeah I wasn’t sure what “cool” means…people have different ideas of cool..mine has the racetrack ducting and both ac units provide cool air to the same duct.

I’m a residential/ light commercial hvac contractor and I won’t even work on window units and I’ve never even pulled the cover on my rv unit…I will one day but assure you it will be under protest…they are just too small and a pain to work on…like the Seinfeld episode where the vet operated on a squirrel after George hit him with a car…needed little tiny scalpels and instruments lol

https://www.youtube.com/watch?v=FieGqyLJYHc

[JOglesby]

Our unit is about 11 months old. I pulled down the inside cover to make sure it's not short cycling. If it's low on refrigerant would it freeze up like a residential unit?
Also coils inside and out are clean, filter clean. We are only seeing like a 7 degree difference at best.

[chuckster57]

Can you do an amp draw test? You can use the black wire coming out of the breaker.

[jasin1]

Originally Posted by JOglesby

Our unit is about 11 months old. I pulled down the inside cover to make sure it's not short cycling. If it's low on refrigerant would it freeze up like a residential unit?
Also coils inside and out are clean, filter clean. We are only seeing like a 7 degree difference at best.

Ac units will freeze up for a variety of reasons…low airflow , obstruction in metering device …and low on refrigerant…if it freezes because it’s low it’s usually just under the correct charge..the more it loses it stops freezing after enough is lost….a 11 month old leak is probably a tiny leak from the factory that took 11 months to reveal itself…or a cracked braze joint…I’d look for oily spots on the copper connections in the refrigerant circuit…although without the skills and tools you will probably spend at least half the cost of a new one to repair if it’s just a fixable leak

[Auto Parts Guy]

Double check that the condenser isn't full of leaves and pollen if you havent already.

If you have access to the evalorator coil, see if it's cold when it cycles, either with a infrared temp gun or your fingers if you can do it safely.

[jasin1]

Originally Posted by wiredgeorge

If he is seeing cold air on the inside of his camper, I suspect the compressor is running and the capacitor is good. It is just as likely he is loosing cooling as the lower unit doesn't have good seals with HVAC tape.

Your tape theory is a good one ..if the return side is missing tape and your pulling in hot air from the tiny attic space it will definitely cause the discharge air to be warmer..it’s only gonna do about a 20 deg ( in a perfect world) split between return air and supply air…if the bedroom is pulling return air from a 75 deg room you will get about 55deg discharge temp..if the living room is pulling 95 deg attic air temp it’s only gonna give you around 75 discharge ..or slightly better as some room temp wire will get pulled in also

[wiredgeorge]

The coils will freeze if the fan is on low air speed and the temp is set relatively high. Been there. Took off my bottom unit after a freeze and a chunk fell on my head. Kind of like Newton and the apple?

BTW: I have many window air conditioners in my shops and have had the cover off and cleaned numerous times. Usually birds get in during the off season when the units are not turned on. If I put a cover on one, turns out I will have to run the thing in what northerners call mid-winter. Saw those poor Toronto fans watching their team standing outside watching a big screen up in Toronto dressed in full winter clothes AT THE END OF APRIL when it is in the 90s here in sunny Texas.

[Ske120]

Our air conditioner wasn’t working and when we took it to the dealer they plugged it in and it worked fine. Paid $80/hour to find out that the camper needs to be plugged into no less than a 30 amp outlet. Has worked great ever since.

[ObiRich]

First thing I'd do is check and make sure the divider between the cold and and return air is in place, sealed, and in the the right spot. Mine had about a 1" gap where the return air was sucking in some of the cold air. Repositioned the divider, and then secured and sealed it with HVAC tape. Made a BIG difference.

You might also want to pull your ceiling vents and make sure they are sealed to the ducts or you're cooling the "attic."

[CaptnJohn]

Originally Posted by Ske120

Our air conditioner wasn’t working and when we took it to the dealer they plugged it in and it worked fine. Paid $80/hour to find out that the camper needs to be plugged into no less than a 30 amp outlet. Has worked great ever since.

I put a Husky Mountain soft start on my 15K Coleman Mach at my neighbor's suggestion. He put 2 on his 5er, he is an electrical engineer and researched all.
I can run that AC on 1 of my 2000 watt Champion generators or from a 20 amp, 110 in my garage with a 25' 14 ga extension to a 50/30/15 dogbone! Have not tried running the heat pump side yet