Damaged a/c condenser fins

[Deb Mac]

Hello all. In another thread I was discussing the addition of the new to me, old (11/89) Coleman Mini mach to my '90 Bigfoot. That all went well, and the unit was performing beautifully.... That is until the ugly heat wave hit us up here. The unit performed just fine until the outside temps went above 35+C, plus the trailer is in full sun, so add several degrees of absorbed heat on top of that.

At that point, the compressor would kick in, but only run for a few minutes, then shut down. Fan still running, but no compressor and no more cold air. Since the evaporator was not frozen (checked that) and it will run fine in the morning before the temperature has a chance to hit "OMG!", my thought was that it is overheating, and the compressor is shutting down.

So with that in mind, I took another look at the condenser fins. They looked like they had been parked on a driving range. Hail is my best guess. Now I had planned to straighten them out anyway - I have ordered a fin comb - but in the meantime, in case the main problem is that those fins just are at the point where in this heat, the poor condenser just can't dissipate enough heat, I spent the last 2 nights sitting on the roof of the trailer with a little spudger tool that I used to open up my iPhone and replace the battery a few years back . And I did my best to open up all of those little fins, one by one. I wanted to have a chance to test my "theory" while the heat wave is still at it's peak here. Once the fin tool arrives, I'll do a proper job on them.

So I'm cleaning them this morning, and I'll test the little beastie once everything dries off.

A couple of pics, before and after below. The first picture, I had already started working on it - about 1/4 the way in from the right. It took about 2 1/2 hours total. I figured I would likely need to open up those flattened fins before even trying the fin comb anyway, so it was not wasted time. And that little spudger allowed me to get right in behind the folds and pull them "straight" from behind. Worked ver well actually. Better than using my little Swiss Army knife blade. That would catch on the aluminum sometimes. This didn't. Went much faster.

Just thought I'd post this as an FYI for anyone interested. Cheers!

[RogerDat]

Be interesting to know how that maintenance turns out. House AC can get the same battered looking fins sometimes. Even short of not working it can't have been a very efficient heat exchange. In that picture it looks like about 1/3 of your fins are not getting air flow around them.

Sitting on a roof, clearly we are NOT the same size individual :-) My sitting on the camper roof is called installing a skylight.

[Alex Adams]

You can also try Air conditioner cleaner. You spray it onto the fins and it foams up removing dirt. It also has material to keep the fins from corroding. You rinse it off with a gentle spray of water. I used it when one of my window AC's started to not cool as well. A bunch of stuff came out and the AC cooled almost like new.

[Deb Mac]

Originally Posted by RogerDat

Be interesting to know how that maintenance turns out. House AC can get the same battered looking fins sometimes. Even short of not working it can't have been a very efficient heat exchange. In that picture it looks like about 1/3 of your fins are not getting air flow around them.

Sitting on a roof, clearly we are NOT the same size individual :-) My sitting on the camper roof is called installing a skylight.

I may have been generous. I was guesstimating 20-25% But it does look like a good 30+% were flattened.

So far, so good - it's been over 30 minutes and still going strong. Mind you, we haven't hit the hot point of the day yet. Only 31C right now. Roof reads 110F in the sun. But a couple of days ago, it didn't run this long even in the morning. By the afternoon, it would go 2 minutes tops, then cut out. So I'll just keep it going and if she runs all day, great!!

[Deb Mac]

Originally Posted by Alex Adams

You can also try Air conditioner cleaner. You spray it onto the fins and it foams up removing dirt. It also has material to keep the fins from corroding. You rinse it off with a gentle spray of water. I used it when one of my window AC's started to not cool as well. A bunch of stuff came out and the AC cooled almost like new.

Hi Alex. I'm going to pick some up. Might not use it, but it won't hurt to have it in the garage. Plus I have 2 window ac's that could probably use a clean-up. I read that a lot of folks just used Dawn dish soap in a spray bottle (my go-to today) and then rinse with a hose - they were concerned about what the cleaner might do to their roof. But they also often had to do 3 or more go-rounds with the Dawn - depending on how munged up things were.

I gave it good brush out first with an old bristle dog brush and only minor dust came out. Washing it really didn't seem to remove a whole lot. I don't think the PO of this unit used it much (he was pulling it from his old mini Winnebago because he wanted a Fantastic fan). The evaporator coils were really quite clean and nothing inside the "hamster wheel" compartment. Everything looked really clean right off the bat. I think the biggest problem is/was the flattened fins combined with the fact that it IS only a 7100 BTU unit.

But at this point, 45 minutes in, she's still going strong. Give it another hour or so and I will have a better idea. Fingers crossed!!

[gordon2]

Could be insufficient power... how do you have it and the camper hooked up? Dedicated outlet? 20 amp? 30 amp? Extension cord? etc....

Monitor the voltage on the circuit and see if it drops and that drop corresponds to the compressor quitting.

[Deb Mac]

Originally Posted by gordon2

Could be insufficient power... how do you have it and the camper hooked up? Dedicated outlet? 20 amp? 30 amp? Extension cord? etc....

Monitor the voltage on the circuit and see if it drops and that drop corresponds to the compressor quitting.

That occurred to me too. It is a definite possibility. It is not on a dedicated house outlet, but it is on a dedicated 20A circuit in the trailer. The outlet at home is only 15A (all there is aside from the stove and the dryer) with nothing else running on it right now (garage), though I have some spare spaces on the panel and have thought about installing a dedicated 20 or 30A circuit just for the trailer. The 30A service is currently connected by a 10g extension cord to the 15A outlet.

So there is a distinct possibility that it isn’t getting enough power to keep up when the temps get really high. Though it works with no problem when the temps are under 35C. That was why my first thought was overheating, and tried the big visible fix first - sort out the condenser fins, since that’s how the heat is dissipated.

I’m hoping that the easy fix corrects the problem. If not, I’ll go hunting for power issues. But so far so good. Has been running over an hour now. It’s currently 33C.

[Deb Mac]

Well it went much better than it has the past couple of days. But the compressor did quit again. Quits, fan keeps running, starts up again and blows cold air for a second then shakes it's head and says "Nope" It is about 3 degrees warmer this morning than it has been, and it ran great for about 3 hours. It is brutal out there, it sits in direct sun (about 130F on the trailer roof), so I think I can't expect a lot more from a 30 year old, 7100 BTU ac. Supposed to cool down to what we would normally call really hot, in a couple of days.

But I think the trailer and the ac could be the least of our problems. Wildfires all over the province, everything is dry as a bone. We could be up in smoke again like we were 4 years ago.

[New Orleans John]

Originally Posted by Deb Mac

Hello all. In another thread I was discussing the addition of the new to me, old (11/89) Coleman Mini mach to my '90 Bigfoot. That all went well, and the unit was performing beautifully.... That is until the ugly heat wave hit us up here. The unit performed just fine until the outside temps went above 35+C, plus the trailer is in full sun, so add several degrees of absorbed heat on top of that.

In New Orleans, I have seen people spray a water mist on the condenser when it gets really hot. I there is a water hose handy, you could try it, it might keep the compressor running.

[Deb Mac]

Last update. Continued to check throughout the end of the afternoon and evening. Once the temperature dropped below 35C and the sun was no longer beating down on the roof, it worked fine. Just came back in from a half hour test run. Everything was great. Ran smoothly as before.

So I guess it's just not going to be enough to deal with the current abnormal temperatures up here, and since I'm not likely to be doing any travelling down south, we should be fine for this season anyway. After the weather breaks (I've spent enough time baking on the roof!) I will take off the shroud & cowlings so I can get at both sides of both coils and give them both a real good cleaning with the foaming cleaner, and beyond that, I don't think there will be much that could be done.

[Deb Mac]

Originally Posted by New Orleans John

In New Orleans, I have seen people spray a water mist on the condenser when it gets really hot. I there is a water hose handy, you could try it, it might keep the compressor running.

Good thought John. Today looks like the last day of real nasty heat, but I'll keep that in mind. I wonder if a few good shots with a super soaker could do the trick if we were out of range of a hose?

[David Tilston]

Originally Posted by Deb Mac

Good thought John. Today looks like the last day of real nasty heat, but I'll keep that in mind. I wonder if a few good shots with a super soaker could do the trick if we were out of range of a hose?

Or my favourite portable swamp cooler:
https://www.homedepot.ca/product/ryo...ly-/1001609196
currently sold out. Maybe it's the heat.


Though it might look kind of funny with that up on the roof of your trailer, spraying into your AC.

[Deb Mac]

Originally Posted by David Tilston

Or my favourite portable swamp cooler:
https://www.homedepot.ca/product/ryo..._EN_UXR843EXPB
currently sold out. Maybe it's the heat.
Attachment 141797

Though it might look kind of funny with that up on the roof of your trailer, spraying into your AC.

I like it! I am a Ryobi fan. Have lots of their gear at home.
I wouldn't care what it looked like, as long as the ac would keep running. Looks rather like a "Roaming Gnome" of sorts.

[David Tilston]

It has come in handy during this heat wave. Though I wish there was a lower spray setting. It has two settings, (three if you include off) but low is not low enough. I am considering modifying it. The two jets, one on each side of the fan, seem to have their own pump, but probably on the same motor. I think I will try to add the option of disabling one. It can also be fed by a garden hose, instead of the bucket.

Since you are a Ryobi fan, (I like puns). You may find this thread interesting:
https://www.fiberglassrv.com/forums/...-to-96048.html

[Deb Mac]

Hey Dave. Doesn't look like ryobi is carrying those in Canada right now. Can't even find them on their .ca website. They do show a similar item - just a misting kit - no fan. Not sure how it works. But HD doesn't seem to have one of those either. Amazon, or eBay. But that is a very interesting little piece of kit. I might have to track one down.

[David Tilston]

Originally Posted by Deb Mac

Hey Dave. Doesn't look like ryobi is carrying those in Canada right now. Can't even find them on their .ca website. They do show a similar item - just a misting kit - no fan. Not sure how it works. But HD doesn't seem to have one of those either. Amazon, or eBay. But that is a very interesting little piece of kit. I might have to track one down.

They are sold out, but that is recent:
https://www.homedepot.ca/product/ryo...ly-/1001609196

I have corrected the link in my previous post.

[Deb Mac]

I will keep my eyes open for them. Hopefully stock will show up soon. ��

[gordon2]

I still would not rule out low voltage. Not only might your extension cord be a factor (you said 10g but did not state the length) but its also very possible the entire grid is low at the peak of the heat of the day. Perhaps a combination of marginal supply to the house and also the wiring and maybe undetected circuit loads... In some areas of the US at least they are even planning rolling black outs to maintain enough power to the areas that remain on. My EMS disconnects the power to the camper if the voltage drops below ~110 and shows an error code to let me know that is the problem. I have seen this occur a few times at campgrounds. Its easy enough to check the voltage and worth doing since continued operation at low voltage might even damage the A/C compressor.

BTW, my home A/C looks worse that your's and still works great after 20 years. I cleaned the coils myself last year with a $8 can from the local hardware store.

[Deb Mac]

Originally Posted by gordon2

I still would not rule out low voltage. Not only might your extension cord be a factor (you said 10g but did not state the length) but its also very possible the entire grid is low at the peak of the heat of the day. Perhaps a combination of marginal supply to the house and also the wiring and maybe undetected circuit loads... In some areas of the US at least they are even planning rolling black outs to maintain enough power to the areas that remain on. My EMS disconnects the power to the camper if the voltage drops below ~110 and shows an error code to let me know that is the problem. I have seen this occur a few times at campgrounds. Its easy enough to check the voltage and worth doing since continued operation at low voltage might even damage the A/C compressor.

BTW, my home A/C looks worse that your's and still works great after 20 years. I cleaned the coils myself last year with a $8 can from the local hardware store.

Definitely not ruling that out Gordon. I don't have a meter to check voltage or amps while its plugged in and running. My neighbour might (retired electrician). Though I suppose I could test the extension cord (25') where it connects to the trailer with my multi-meter, and see what is actually getting to the trailer from the house. Likely not quite the same animal though. Be worth investing in.

I did run the original 11,500 BTU Dometic on my 40 yr old GMC motorhome on the same circuit with no problems. Though, again, we weren't dealing with this kind of heat. This was not anywhere close to normal around here. We've never had any issues with brown-outs or power drop-off up here (very small town in the mountains), but there has never been a bout of heat like this either. I did have my entire house inspected and updated several years ago so the incoming feed from the main is good, and the wiring in the house itself is up to snuff - several new circuits, new panel (hence the spare spaces on the the panel available for a dedicated line to the trailer )

Looks like it may not be much of an issue for a while now so might not be able to check it out anyway. Our temps are dropping back into the low to mid 30's instead of the high 30's to low 40's, starting today. But I will check into possible low voltage issues. A distinct possibility that these kinds of heat events are going to become more frequent around here.

Pleased to know that my coils weren't as bad as they appeared to be
And Happy Canada Day to all! 🇨🇦

[gordon2]

Originally Posted by Deb Mac

... I don't have a meter to check voltage or amps while its plugged in and running. ..Though I suppose I could test the extension cord (25') where it connects to the trailer with my multi-meter, ...

Yes all you need to do is use a multimeter or voltage meter to check the voltage on the same outlet with the A/C. Or use a splitter, as close to the A/C as you can manage. Just be careful when inserting the leads. While it would be nice to know the amp draw, if the voltage drops below about 110 then you will know what the problem most likely is. And if the compressor quits at the same time, you get to yell out, "BINGO!"

In the all time record setting heat some areas are having, I would like to keep an eye on my voltage anyway because of possible brownouts.