AC Cuts Out

[mikell]

Older Coleman unit runs and cools about 10 minutes then the compressor shuts off. It still needs to be cooling ?? Low Freon or?? Will have more time to work with it this weekend

Thanks

[chuckster57]

When it runs is the exhaust air cold? If so how cold? When it shuts off, will it come back on after a bit? If so, then it may be "Freezing up". There is a freeze sensor that sits in the fins on the intake side. You'll need to remove the ceiling plenum to access it.

Make sure its in place and the intake and discharge chambers are well sealed from each other. With the plenum off you will see a divider in the middle, make sure its in place and all edges sealed.

Post back and we can take it from there.

[GaryWT]

If then fan is still running and it comes back on by itself then it is just cycling. Mine will do that when you first turn it on until the trailer is cooled to the set point. Like said, if it stayed on it would freeze.

[Nagrompj]

Originally Posted by mikell

Older Coleman unit runs and cools about 10 minutes then the compressor shuts off. It still needs to be cooling ?? Low Freon or?? Will have more time to work with it this weekend

Thanks

Low freon or a dirty condenser can cause the high pressure switch to open and stop the compressor. Get up on the roof and make sure the condenser is clean and not blocked. If you find all is well have the freon checked.

[chuckster57]

There are no service ports on an RV A/C so determining amount of refrigerant is not an option.

[Nagrompj]

Any AC tech can add ports. So it is a option.

[Bob Landry]

Originally Posted by chuckster57

There are no service ports on an RV A/C so determining amount of refrigerant is not an option.

These units can be checked for proper charge using a clamp on ampmeter and measuring compressor current draw.

[chuckster57]

Originally Posted by Nagrompj

Any AC tech can add ports. So it is a option.

I suppose if a person wanted to pay the labor cost a tech could. BUT that would require opening up the system, and since there is no way to recover the refrigerant prior to that, there is no way of knowing what the charge is.

[Bob Landry]

Originally Posted by chuckster57

I suppose if a person wanted to pay the labor cost a tech could. BUT that would require opening up the system, and since there is no way to recover the refrigerant prior to that, there is no way of knowing what the charge is.

No, it doesn't require opening the system. That's the point of using a clamp-on meter. You put a meter on the compressor common lead and measure current. The amp draw listed for the compressor is for an ambient air temp of 95 degrees. A 10 degree shift in ambient temp will cause a 1 amp change in the compressor current draw either way. If the draw is supposed to be 13 amps and it's 105 outside, the current draw would be 14 amps and you interpolate for changes in between. If the temp was 85 then the draw would be 12 Amps. That's how Dometic says to check them and the same would apply to the Coleman units.

[chuckster57]

Yeah I understand that. Have done it as its required test for warranty replacement.

My reply was about service ports.

[Nagrompj]

The system does not need to be opened to add service ports.
In fact a service port needs to be added just to dispose of the unit. All of the freon needs to be reclaimed by law and the only way to do that is add a service port.
Disposing a unit in any other way would potentially open yourself to huge fines.

[Fishhawk]

If you have a digital thermostat
Set the fan
From auto to manual .... Either low or high
This prevents the thermostat from turning the fan off too soon while allowing the compressor to keep running until the limit swt shuts it down
With the fan on manual, it ran all the time and the compressor would run through its normal cycles


One year in early spring when the outside temps ranged from hot to cool
I had the same type problem you have described
I found that doing this worked for me

Cant hurt to try it

[mikell]

Thanks for the ideas but it's been raining and cold so it's going to have to wait as week. I was told the unit was removed to fix a roof leak. Maybe later in the week.

Thanks

Mike

[Bob Landry]

Originally Posted by Nagrompj

The system does not need to be opened to add service ports.
In fact a service port needs to be added just to dispose of the unit. All of the freon needs to be reclaimed by law and the only way to do that is add a service port.
Disposing a unit in any other way would potentially open yourself to huge fines.

A port for reclamation would have to be added via a piercing valve which clamps around the tubing and uses a needle to pierce the tubing. It takes about two minutes to install and can be removed easily when finished.

[dcg9381]

Originally Posted by Nagrompj

The system does not need to be opened to add service ports.
In fact a service port needs to be added just to dispose of the unit. All of the freon needs to be reclaimed by law and the only way to do that is add a service port.
Disposing a unit in any other way would potentially open yourself to huge fines.

How do you add a coolant port without opening the cooling system? Crimp, solder and un-crimp?

[Bob Landry]

Originally Posted by dcg9381

How do you add a coolant port without opening the cooling system? Crimp, solder and un-crimp?

You don't.

You have to sweat in a "T" and a shrader valve in the suction line. To do that the system has to be evacuated so you do not add freon, you do a complete recharge. That's why you use a clamp on meter to measure compressor amp draw to see if it in fact low on charge. There is no reason to tap into it if it isn't low on charge. You could use a piercing valve and gauges to check the low side pressure of the running unit, but the valve would have to be removed and before you could solder the hole made by the piercing valve, you would loose the charge anyway, so doing it that way is really counter productive. You can not just leave a piercing valve in place because they leak.
the first reaction and suggestion by people who do not understand air conditioning is to simply "add freon", but that is not always the problem. In fact, it is seldom the problem, but that's what people read on the Internet, so that's what gets suggested.

[Nagrompj]

I love how people like to jump on others just to try to prove their superiority. I never suggested opening the system. That was others jumping to conclusions. (Although it would be a minor task on a system that small). If the manufacturer has amp/temp chart then by all means use it.
The fact is low freon or a dirty or blocked condenser on a "older air conditioner" are the first things to be ruled out. At least that is what I read on the Internet.

[Bob Landry]

Originally Posted by Nagrompj

I love how people like to jump on others just to try to prove their superiority. I never suggested opening the system. That was others jumping to conclusions. (Although it would be a minor task on a system that small). If the manufacturer has amp/temp chart then by all means use it.
The fact is low freon or a dirty or blocked condenser on a "older air conditioner" are the first things to be ruled out. At least that is what I read on the Internet.

Sorry if you interpret some of the posts on here as a demonstration of superiority, but a few of us on here do have a background in air conditioning and are able to offer suggestions that are relevant to troubleshooting the issue being discussed in the thread, while trying to keep the owner safe while doing it, and not just parroting something that was posted on the internet by an armchair technician who probably struggles trying to use gauges or a voltmeter.

BTW, a low freon charge does not cause high head pressure, so I have to ask, what is your background in refrigeration?

It's not my intention to sound harsh, but after you have been on these forums for a while, you will see threads by people wanting help and getting responses from others who don't have a clue what they are saying but just want to get in the conversation and are offering dangerous and in some cases, potentially deadly advice and the new owner doesn't know how to sort it all out. If he did he would not be on here asking for help.
The electrical threads are the worst ones. People don't seem to care that they could literally kill someone with the advice they are giving.
The bottom line is don't throw out BS answers on things unknown to you.

[Nagrompj]

Originally Posted by Bob Landry

Sorry if you interpret some of the posts on here as a demonstration of superiority, but a few of us on here do have a background in air conditioning and are able to offer suggestions that are relevant to troubleshooting the issue being discussed in the thread, while trying to keep the owner safe while doing it, and not just parroting something that was posted on the internet by an armchair technician who probably struggles trying to use gauges or a voltmeter.

BTW, a low freon charge does not cause high head pressure, so I have to ask, what is your background in refrigeration?

It's not my intention to sound harsh, but after you have been on these forums for a while, you will see threads by people wanting help and getting responses from others who don't have a clue what they are saying but just want to get in the conversation and are offering dangerous and in some cases, potentially deadly advice and the new owner doesn't know how to sort it all out. If he did he would not be on here asking for help.
The electrical threads are the worst ones. People don't seem to care that they could literally kill someone with the advice they are giving.
The bottom line is don't throw out BS answers on things unknown to you.

Will you just admit a dirty or blocked condenser or low freon will cause the compressor to cycle off? Maybe you don't know. Or is beating me down your only goal.

I do not expect the op to know the difference between a high compressor discharge and low suction, so I did not think it necessary to explain myself. If he did he would not have ask for help.

Remember I never suggested adding a service port to troubleshoot. That was suggested by others. I only rebutted it can be done with little trouble if needed.

BTW we don't "sweat" we braze refrigeration lines. There is about a 800 degree difference.

So I guess the lesson here is throw your old a/c off the roof and get a new one. But only if you are qualified to use a ladder and are a qualified electrician and are an experienced mechanic and if you have properly troubleshot your old a/c and have your EPA Universal refrigeration certificate (as I do). And whatever you do don't take any advice from someone with less than 1500 post (they don't know what they are talking about) And DO NOT take to someone and have the freon charge checked with a amp meter or by any other means because if it comes up low it would be to much trouble to repair.

Sorry I tried to help I will not do it again. I'll just sit in my armchair and not offer any "BS" advise. I don't need to be harassed just for trying to help.

[chuckster57]

Clearly this thread has derailed. I may have contributed at the beginning of the wrong turn, but I have since sat back and watched this turn into something totally different that what the ORIGINAL thread was about. Before anybody disrespects anyone else, let's all take a chill pill and call this thread done.