Damaged a/c condenser fins

[Friz]

Sitting in the sun is a big part of the problem.

Find some way to make a shade for the AC. Find an old plastic political sign, trim it to a little larger than the size of the AC. The steel supports can be formed into legs. Fasten a rubber tip to the legs so it doesn't scratch the fiberglass. Make it resemble a small coffee table. Glue some aluminum foil to the topside. Use bungees to keep it from blowing off. Now you will be all set for camping in Texas. 35^C is a normal summer day here.

To really cool off the trailer, I made a "tent fly" for mine. 8' x 12 ft tarp with foam blocks on the underside. The foam blocks should be tall enough to clear the air conditioner and the roof vent. Makes a difference of 75^ inside vs 90^.

Using a water mist to aid the AC to cool better works good, but eventually makes a mess and corrodes the aluminum. I used that on an AC that was about to die.

[sunnyone]

Originally Posted by Friz

Sitting in the sun is a big part of the problem.

Find some way to make a shade for the AC. Find an old plastic political sign, trim it to a little larger than the size of the AC. The steel supports can be formed into legs. Fasten a rubber tip to the legs so it doesn't scratch the fiberglass. Glue some aluminum foil to the topside. Use bungees to keep it from blowing off.

Clever. I’m thinking something like this might work to improve the functioning of my refrigerator when the Scamp is sitting in the sun.

[Deb Mac]

Originally Posted by gordon2

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. 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.

Hi Gordon. Well I can't test something on the same circuit because the ac is on it's own dedicated circuit. But, what I was able to do was check what was happening on the main 120V circuit. With nothing running on 120V, the output reads 120v on my multimeter. But when I turn on the ac, the reading is 108. And although the ac is running fine this morning, and last night, when the temps were consistent with life, when they get too high (like over 35C & the sun directly on the roof) maybe it's more than it can handle.

I would love to check the outlet voltage at the same time the compressor kicks in. Unfortunately, that 3rd hand hasn't arrived yet I'm going to see if I can stretch between the outlet and the control knobs on the ac, and still keep the MM probes in the outlet. One thing I can do is run it off of the generator and see if there is any difference with the trailer plugged directly to the generator - no extension cords, just an adapter for the 30A to 20A outlet.

But it does look like there may be enough of a power loss that it is at least one factor in my compressor woes. Thanks for the input. Learning all the time!

[Deb Mac]

Originally Posted by Friz

Sitting in the sun is a big part of the problem.

Find some way to make a shade for the AC. Find an old plastic political sign, trim it to a little larger than the size of the AC. The steel supports can be formed into legs. Fasten a rubber tip to the legs so it doesn't scratch the fiberglass. Make it resemble a small coffee table. Glue some aluminum foil to the topside. Use bungees to keep it from blowing off. Now you will be all set for camping in Texas. 35^C is a normal summer day here.

To really cool off the trailer, I made a "tent fly" for mine. 8' x 12 ft tarp with foam blocks on the underside. The foam blocks should be tall enough to clear the air conditioner and the roof vent. Makes a difference of 75^ inside vs 90^.

Using a water mist to aid the AC to cool better works good, but eventually makes a mess and corrodes the aluminum. I used that on an AC that was about to die.

I am working on a way to set up a bit of a sun shade. That occurred to me when this whole thing started happening.

[gordon2]

What model of Coleman Mini mach is it? What are the specs?

[Deb Mac]

Originally Posted by gordon2

What model of Coleman Mini mach is it? What are the specs?

Hi Gordon. It is a 6727D709. I can’t find specs on this one & I have been hunting since last fall when I picked it up - it’s a rotary compressor (the 7 in the 709) but I did track down the specs for the 800 series. That is a repriprocating compressor. From what I have read, the rotary last longer and are more efficient though more expensive out of the box.

I’m attaching the spec page for the 800 series. Mine does not have a heat option. Just cooling so I have been working from the assumption (might be a mistake) that the specs are probably pretty close.

Airxcel and RVP can’t help me. Too old they tell me. ��

[gordon2]

I'm not sure how to interpret the specs but it does look like it should be OK on dedicated 15 amp circuit. I find the reference to 103.5 volts interesting.. does that mean it can actually work at that low a voltage I wonder.. I was under the impression that the lower limit for most RV A/Cs was 105-110. So perhaps it's age is more of a factor... and it just cant handle the hottest temps you have recently seen. Or the fins are one of a combination of issues. It would be interesting to see how it does on a 3500+ watt generator that could maintain 110+ Volts under the same conditions of extreme heat but that test sounds impractical. So it is what it is for now I guess.

[Deb Mac]

I have little idea about a lot of those specs. But I think it is saying that it can run at 103.5V. If I look at the watts and amps for each condition, they coincide with a 103.5 V input.

So yep, until I can get it on a generator under the same conditions to check the incoming voltage scenario, I think I’ll go with “can’t handle that heat” and be proactive and work on getting a light & easy to deal with, sun shade for the top.

Thank you for all of your help and suggestions on this Gordon. If I find I have any significant follow-up, I’ll come back. Cheers.

[redbarron55]

There could be a high temp switch in the compressor and it is getting good and hot there in the sun + the load on the system.
You could check the electrical drawing for the possible high pressure cut out if any and also check for current draw.
If low on working fluid the unit would not cool well and would not have enough coolant flow to remove the heat from the compressor?
Check the amp draw as there may be a thermal switch that cuts off the compressor, either within the compressor or attached to it.

[gordon2]

Originally Posted by Deb Mac

... I think I’ll go with “can’t handle that heat” and be proactive and work on getting a light & easy to deal with, sun shade for the top.
...

As long as it lasts.. this is what I have. I beefed it up so it can take a good amount of wind, and I think the way I did it will mean that the fabric will rip off before the frame breaks apart and maybe damages the Scamp. Snow will kill it pretty quick but we had none here last year. Total cost about $150 US.

So while it might not work for your location.. a sun shade might well be the best option to keep your A/C running in very high heat... GL.

[Deb Mac]

Originally Posted by redbarron55

There could be a high temp switch in the compressor and it is getting good and hot there in the sun + the load on the system.
You could check the electrical drawing for the possible high pressure cut out if any and also check for current draw.
If low on working fluid the unit would not cool well and would not have enough coolant flow to remove the heat from the compressor?
Check the amp draw as there may be a thermal switch that cuts off the compressor, either within the compressor or attached to it.

There is an overload switch in the compressor part of the wiring diagram. But if it’s heat or current, I’m not sure. But from your description, a current overload would cause excess heat in the circuit, (the switch) and that would trip a thermal overload switch. So actual excess ambient temps could do the same thing? But, these specs are not actually for my compressor. Mine is rotary, these specs are for a reciprocating compressor (all I could track down for the Mini).

I’m also not sure if this one can be recharged in case the coolant may be low. I seem to recall that it can be, but wouldn’t bet the farm.

I’ll see if I can borrow my neighbour’s clamp meter to check the current tomorrow.
Continuing saga!

[Deb Mac]

Originally Posted by gordon2

As long as it lasts.. this is what I have. I beefed it up so it can take a good amount of wind, and I think the way I did it will mean that the fabric will rip off before the frame breaks apart and maybe damages the Scamp. Snow will kill it pretty quick but we had none here last year. Total cost about $150 US.

So while it might not work for your location.. a sun shade might well be the best option to keep your A/C running in very high heat... GL.

I would love to build a nice shelter for my trailer, but our little municipality doesn’t allow temporary “garages” or similar shelters to be closer to the front property line than the front of your house!
And since we are parked in what was the front yard, now parking, (grass doesn’t like the excess amounts of pine needles around here) I can’t set one up

I am working on a sun shade plan that will shade the majority of the roof. Let’s see how it all works out.

[Franknank]

Get a A/C fin Comb (Google)and you can comb them straight and re-open the gap between the fins

[Deb Mac]

Originally Posted by Franknank

Get a A/C fin Comb (Google)and you can comb them straight and re-open the gap between the fins

Have one coming. Ordered it when I decided to do something about the fins & it should be here tomorrow. No one local had one so I used the spudger in the meantime. Most of those fins were so badly smashed that I would have had to pull a lot of them out one by one anyway before I would have even wanted to try the comb. Once it's here I'll do a better job of it, but had to try something while I waited.

[PatrickTXFL]

Would be worth checking specs on the start capacitor. The further they weaken to be out of specs the more likely that high pressure restart might be too much to complete.

So you have a 25 foot 10ga extension plugged into your 30amp cord that i would guess is another 20 foot. Your plugged into an outlet that is smaller than preferred, so be sure to feel all plugged parts to see if anything is getting warm.

You can put the meter in any plug in TT and see the voltage drop as AC cycles as the loss is happening to entire TT. The normal start load is so fast a peak that your meter might not even display it when AC starts normally, but should be able to see if going into overload when failing to start.

Measure the temperature in RV then during time of day it will run good turn on and measure temperature drop at vent. 15 or above would indicate that gas levels are good and compressor is able to still reach good pressures. If this is true then suspect the start capacitor might be out of range. If not very knowledgeable get an AC guy to test the start capacitor, or they are so cheap and its so old you may want to just change. NOTICE risk of shock so take care to be safe and get help or educate yourself.

[Deb Mac]

Originally Posted by PatrickTXFL

Would be worth checking specs on the start capacitor. The further they weaken to be out of specs the more likely that high pressure restart might be too much to complete.

So you have a 25 foot 10ga extension plugged into your 30amp cord that i would guess is another 20 foot. Your plugged into an outlet that is smaller than preferred, so be sure to feel all plugged parts to see if anything is getting warm.

You can put the meter in any plug in TT and see the voltage drop as AC cycles as the loss is happening to entire TT. The normal start load is so fast a peak that your meter might not even display it when AC starts normally, but should be able to see if going into overload when failing to start.

Measure the temperature in RV then during time of day it will run good turn on and measure temperature drop at vent. 15 or above would indicate that gas levels are good and compressor is able to still reach good pressures. If this is true then suspect the start capacitor might be out of range. If not very knowledgeable get an AC guy to test the start capacitor, or they are so cheap and its so old you may want to just change. NOTICE risk of shock so take care to be safe and get help or educate yourself.

Hi Patrick. I did check voltage on another circuit and when the a/c was running, voltage dropped from 120V to a steady 108V. Same thing (I managed to be able to stretch from the socket to the ac) when it starts up. It's when the outside temps hit over 35C AND there is direct sun on the roof all day (there no way to shade it and it is in the full sun from 10 am till sunset) that the problems start. The temperature on the roof of the trailer got to 130F. If it is a more manageable temperature, everything runs just fine.

I also tried starting it up in the morning and letting it run to see if keeping the inside cooler from the start would keep it running - instead of starting with an overly hot trailer. Tried low thermostat and high fan, low thermo and low fan, no ac & just fan to start then turned on the ac. No matter what combination, once that temperature outside hit about 35C (and therefore the roof was well over 50-55C) the compressor would quit. So my thought is still that it is heat related. Now whether the start capacitor would be affected by high temps, I don't know. But the overload switch on the compressor may be a high temp limit switch, and if that's the case, then the excessive temps might be "misinterpreted" as an overload. Unfortunately, I wasn't able to check during the times of compressor shut down. And temps are back to normal seasonal highs here again, so it may be a while before I get a chance to check again.

I did check the temp at the vent when I first installed it and tested it out. It was 38C in the trailer and 21C at the vent, so pretty sure the system is gassed up & compressor itself is good It is entirely possible the start capacitor is on it's way out though. It is a 30 yr old unit, but I will hang on to it. Rather fix it than replace it. So maybe I'll pick up a capacitor anyway - like you said, it's old and doesn't really owe me much - and before the temps get back into the ugly range, I'll swap it out.

[PatrickTXFL]

Another thought. Have you investigated the electrical panel and the feed from external plug to panel. Being older you need to be sure to do a full check, loose or bad connections could be part of your voltage drop. The voltage drop can cause AC compressor to heat up, that combined with heat might make compressor hit overload.

Last year my 2015 trailer had loose connections on all neutral and ground bars that were so hot they were starting to melt the panel. I had to replace the bus bars and shorten wires to get clean metal. Usually you can see insulation has changed color if wire is heating up. The outside wall plug the 30amp power cord plugs into is another point that goes bad from people pulling to many amps, often in cold weather camping with electric heaters.

[Lloyd (aka Santa) Coltman]

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?

Some A/C units depend on a portion of the condenser cooling being from evaporation of condensate drained from the cool side and being flung at the condenser.
As for the size of unit you've got, most think it needs to drop temperature immediately. Not so, my neighbour cooled his 24' 'Tin-wall' quite nicely with a 5200 BTU,'window-hanger' (in the Okanagan). It just took a while to cool down, so you sit under the awning, and sip a cool beverage.
BTW, I have a 13,000 BTU on my 24' and it takes a while to cool, after being in blazing sun for hours.

[Lloyd (aka Santa) Coltman]

Something to consider: almost any outlet close to the trailer's 'Power Centre' will give you almost identical readings to what the A/C will see, as most of your loss will be in the 15A house wiring (14 Ga unless new standard and over 50'. In which case it would be 12Ga). At home, in Kelowna, I can easily run a 13,500 BTU A/C, Converter, and Fridge on a proper 20A (12 Ga. approx 50' )+ 25' 10Ga umbilical.

[Deb Mac]

Originally Posted by PatrickTXFL

Another thought. Have you investigated the electrical panel and the feed from external plug to panel. Being older you need to be sure to do a full check, loose or bad connections could be part of your voltage drop. The voltage drop can cause AC compressor to heat up, that combined with heat might make compressor hit overload.

Last year my 2015 trailer had loose connections on all neutral and ground bars that were so hot they were starting to melt the panel. I had to replace the bus bars and shorten wires to get clean metal. Usually you can see insulation has changed color if wire is heating up. The outside wall plug the 30amp power cord plugs into is another point that goes bad from people pulling to many amps, often in cold weather camping with electric heaters.

Hey Patrick. The panel was upgraded a few years back. When I installed the new circuit (20A breaker as per specs using 12/2 Romex) I checked the other connections (weren't many!) and they seemed nice and secure. Insulation was in great condition and the copper I could see was also normal.

My unit has the 30A cable wired directly into the panel, and the cable is pulled out of the bay to plug into the power source (house, campground power pole, etc). And it all looks good at both the plug and the panel. So I'm thinking both the panel and 30A cable/plug are in good shape. But, I will give it all a good going over again, in case I missed something.