Roof top AC not cooling

[Bourgon]

Hi Everyone,

First, we have a 2019 Outlook 22C. It’s almost new with only 6000 miles on it. We bought it about 12 months ago, pre-owned, very lightly used. It’s equipped with a Coleman Mach 3 15,000 BTU AC unit on the roof which is controlled by an analog wall mounted thermostat.

Apart from testing it when we bought the RV, we haven’t used the AC. We were planning something for this weekend and we’re in the middle of a heat wave, so I wanted to test it. I tried it with shore power, forgetting that it’s a 15 amp circuit. The fan obviously worked and when I switched the AC to on, the sound changed but after 10 or 15 minutes, there was no cooling. The 15 amp circuit breaker in our home breaker panel didn’t trip.

Thinking that it might be due to low voltage, I tried it again while running the onboard generator, a Cummins QG4000. Again, same thing; fan runs but no cooling. I understood that the AC could run on the generator but maybe that’s wrong.

Questions:
Is the AC broken / malfunctioning?
Did I break something by turning it on while on a 15 amp circuit?
Is it because of low voltage?
Should I be able to run the AC on the generator power?
Could it be one or both of the capacitors?
Something more major?
Should we run the AC periodically so it doesn’t seize up or something?

Any help would be greatly appreciated. After watching some YouTube videos, I’ll likely climb up there in the coming days to test things.

Thanks,

Luc

[ThomB]

Not sure if you'll get the same results but I changed out the run and hard-start capacitors (about 2 weeks ago) and mine started to produce cold air again. I think low-voltage was my issue.


I was able to find the capacitors at a camping world, but also bought this one (haven't installed it). Might be a cheap option to see if it helps.


https://www.amazon.com/dp/B00DZUAPQG...roduct_details

[Bourgon]

Thanks ThomB.

I went up on the roof and removed the cover to have a look and get model and part numbers. I decided to give it a try and see what was going. I started the generator, which should in theory, produce enough power to run the AC (40 amps). Started the fan and it worked fine, which I already knew. When I went back on the roof, the only thing that I noticed was that the compressor was getting hot, so I went back down and turned everything off.

Not sure if my logic is correct but I think that would still point to a bum run capacitor. The lack of kick from the capacitor isn’t allowing it to start, but it’s still getting power.

Anyway, ordered a new run capacitor, and splurged on a SoftStartRV. From what I’ve read on multiple forums and websites, the soft start option is preferable to the hard start. More expensive upfront but better long term.

I should be getting both mid next week. I’ll see then. Hope it works!

Luc

[deckape]

Check/tighten all connections , terminals, and where wires ,120v come in. If you know how ,ohm across each terminal on compressor and across o/l kic-on to see if any are open. You should get a reading. I would also get the correct connection for plugging in your RV to the house. Low voltage today can kill alot of equipment .

[Bourgon]

Thanks for the info and advice. I’ve already purchased everything I need to install a 30 amp service but this took a back seat while I was trying to repair the unit.
Okay! So I went back on top with all my equipment and found the following:
* Run capacitor: good, capacitance within specs
* Fan capacitor: good, capacitance within specs
* PTCR: appears good. 0 ohms resistance when cool
* Compressor windings: good
* Nothing going to ground
* Thermostat: good. It’s doing all of the right things according to the Coleman thermostat service manual.
I did find something suspicious that I believe points me to the conclusion: it appears that prior to our purchasing this very lightly pre-owned RV, someone had to refill the system and installed what I’ve now found to be a Supco BPV piercing service valve on one of the “low pressure” lines. Everything I found online says that the refrigerant system is a closed-loop with no OEM installed refill points.
Although I haven’t seen signs of a leak anywhere, to me this means that someone already had to refill the refrigerant since 2019, the year the Winnebago was built.
I now have three options:
* Find someone who will refill the system
* I’m pretty sure this will be pretty expensive.
* Source the equipment and R410-A Puron refrigerant and refill myself, also expensive and challenging,
* Finding relatively small quantities of Puron is proving to be difficult.
* Replace the unit.

Refilling would clearly need to be done every year or two, which would become quite expensive in short order. Replacing the unit would be expensive upfront but would be a “permanent” fix which I can easily do on my own. There are only a few bolts holding this down and a handful of electrical connections. The only challenge in this would be getting the 80 lbs unit on the roof but I may have a solution right in my driveway.

Any thoughts?

[ThomB]

WOW on that new of a unit to have added refrigerant seems odd and likely your culprit to no cooling. You could try a can from the auto parts store to recharge, but like you said it's likely just going to last only a year or so but it's also not that expensive.


Is this an air only unit or a heat pump? Air only units aren't too expensive, but heat pumps can get up in the low-1000's. If you do have to change it out, yes, the toughest part is getting the new unit onto the roof and the old one off (if you don't use the gravity method). I replaced one with my brother. One on top of the RV and the other pushed the new unit up a ladder until we passed it to the other. It worked on and off. After that it's just getting the upper unit situated over the hole and the 4 bolts done. pretty simple!

[creativepart]

Originally Posted by Bourgon

The only challenge in this would be getting the 80 lbs unit on the roof.

This ^... is the main reason these are replacement items and not repair items.

If you get it down and take it to an A/C shop they may work on it. But without getting it off the roof no one will touch it.

If the compressor is hot and not running I'd guess it's been run low of oil when the refrigerant was low. It's just a guess that that's my guess. And, everyone says the compressor is not replaceable.

[Bourgon]

Yep. I really think that’s the culprit. I can’t see why else a refill valve would have been added.
It’s a Coleman Mach 3 13,500 BTU cooling only unit. Unfortunately, the lowest price I’ve found in Canada is around $1300. If I’m going to replace it, I think I’ll upgrade to the Mach 3 Power Saver which I can get for about $1400. The PS unit has a higher refrigerant load (17.75 oz. vs 11.50 oz.) and the running watts are 1320 Watts (“desert load”) for the PS unit vs 1695 Watts for the regular unit.
Either way, it’ll be free shipping but taxes will push it around the $1600 range. I can think of many other things I would have liked to spend $1600 on but it is kind of essential when we get heat waves like we just had and the temperature inside got to 96 F.

[ThomB]

We were at a Camping World in Indiana and the “parts guy” said they just got a huge shipment of them. I think they’re around $700 US right now. Sounds like if/when the border opens a trip might actually be cheaper to get one here.

[Bourgon]

ThomB, thanks!
I took your advice and looked at prices across the border. What a difference! I found the model I was looking for at a major US RV parts retailer for $699.97 USD so I placed an order. Their policy for international orders is to contact the customer with the shipping charges before completing the order, so it was a pretty safe bet.

They emailed me today with a shipping quote to Canada of $97 USD so I approved the order. Even with the exchange rate, it came out to $1007 CDN.

That’s a savings of over $600 CDN. That’s way better than over $1600 CDN, taxes in. Now I fully expect to pay some brokerage and possibly some taxes/duty charges but it’ll never be over $600, so I should come out on top by a few hundred bucks.

Now, I need to find a way to get that on top of the RV…

[creativepart]

Originally Posted by Bourgon

Now, I need to find a way to get that on top of the RV…

I had mine changed out in a campground. The man leaned an extension ladder at an angle against the back of the RV. He unboxed the A/C and tied a rope around it like a package. Then he leaned it against the bottom of the ladder and climbed up. Once standing on the roof he pulled on the rope, sliding the 80 lb A/C unit up the slope of the ladder until it was at the top of the roof and he could pull it flat on to the rooftop.

Isn't this is how the Egyptians built the pyramids, too?

[Bourgon]

That’s what I was thinking also.
The retaining wall on one side of my driveway is about 5’ tall. The driveway is almost perfectly flat. A little over from that retaining wall are the steps leading up to the landing by the front door. I figure that if I back in carefully I’ll only have about 5’ or 6’ more to go to get it on the roof. I should be able to get the unit on the landing with relative ease. From there, I’ll use one of my ladders as a ramp.
I have some scrap wood and plywood and I was thinking of throwing together a makeshift sled with a runner on each side of the ladder. That way, I could center the load and keep it centered as I pull it up.
If not, brute strength may be the answer. It’s only 80 lbs.

[ThomB]

My brother and I lifted one on my roof. He went up top and I pushed the unit up an A-frame ladder until he could reach it. Getting the old one down was a reverse of that. Some use the gravity method to get the old one down…