Air Conditioner Check

[magnmike]

What's the best way to check the temperature of the air blowing out of the air conditioner?  What kind of thermometer can I use?
Also, what minimum temperature should the air be blowing to adequately cool?

I realize it can depend on outside temperature, etc, but mainly I'm trying to determine if my unit is cooling as it should.  Last trip in April it was not cooling consistently.  I have now cleaned the filter and will be taking a look at the coils before I place the cover back on and run the unit.

Right now it's in the low to mid 80's during the day.

[CajunCamper]

What's the best way to check the temperature of the air blowing out of the air conditioner?  What kind of thermometer can I use?
Also, what minimum temperature should the air be blowing to adequately cool?

I realize it can depend on outside temperature, etc, but mainly I'm trying to determine if my unit is cooling as it should.  Last trip in April it was not cooling consistently.  I have now cleaned the filter and will be taking a look at the coils before I place the cover back on and run the unit.

Right now it's in the low to mid 80's during the day.

I'm not an AC guy or anything, but I believe the air coming out of the AC should be 10 to 15 degrees cooler than the inside of the room it's cooling. Open your pup and start the AC, let it run for a while so it has a chance to cool the pup. I would do this at night so you don't have the heat of the sun to deal with, then stick a thermometer in the vent and put a thermometer in the pup and see what the difference is.

I could be wrong, but I'm sure someone here that really knows this stuff will correct me if I am.

[wavery]

Once the AC is cooling for awhile (maybe 15 minutes), you should get around 40 degrees right inside the outlet.

There are many types of probe thermometers that you can buy from any auto parts store that are made for checking the AC temp in the outlet. Here is a common one:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46586

[magnmike]

Thanks.  I'll check out this evening.  Let's hope cleaning the filters did the trick!

[magnmike]

Ok.  Turned on air and let it run about 15 minutes.  Went back out and inserted probe thermometer.  Compressor was not running at it read 70 degrees.  Once the compressor cut on it got down to approximately 52 degrees before the compressor cut back off (about 3 1/2 minutes of compressor running).

Does this sound like it is operating properly?

[wavery]

Ok.  Turned on air and let it run about 15 minutes.  Went back out and inserted probe thermometer.  Compressor was not running at it read 70 degrees.  Once the compressor cut on it got down to approximately 52 degrees before the compressor cut back off (about 3 1/2 minutes of compressor running).

Does this sound like it is operating properly?

What was the outside temp?  If it was cool out, it may not be running long enough to cool the coils all the way down before the thermostat cut it off.

Did you have it turned all the way down? If you did, it shouldn't be cycling with the coils that warm. It could be low on freon or the thermostat or thermocouple could be bad.

If the outside air was in the 60s, it may be to cool to run your test.

[magnmike]

What was the outside temp?  If it was cool out, it may not be running long enough to cool the coils all the way down before the thermostat cut it off.

Did you have it turned all the way down? If you did, it shouldn't be cycling with the coils that warm. It could be low on freon or the thermostat or thermocouple could be bad.

If the outside air was in the 60s, it may be to cool to run your test.

About 72 outside.  I had it on Hi Cool as cold as it would go.  If low on freon that can't be serviced can it?  How could I test thermostat or thermocouple?  Is that easily fixed.

[Camp&Fish]

What is your electricity source?  From what I've read, the 15 amp service at home isn't enough to power the A/C unit to full capacity.  That only comes with 30 amp service.  When I tried my A/C unit at home, it barely got cool.  When I tested it at the dealer when I picked it up (plugged in to 30 amp service), it got cold within minutes.

[wavery]

About 72 outside.  I had it on Hi Cool as cold as it would go.  If low on freon that can't be serviced can it?  How could I test thermostat or thermocouple?  Is that easily fixed.

I'd try the test again when it's a little warmer.

Try sticking your thermometer in the AC duct of your car. That will give you an idea of what you should have. You may not get 40 degrees, like your car does (should) but it should be close. High 50's seems a bit high to me.

15A service should run your AC just fine. If it draws too much, it will pop the circuit breaker. To be certain, check the voltage in one of your campers outlets while the AC is running. If it's 110V+, you're doing fine. If it is below 105V, you could have a problem. That is usually due to using an extension cord to plug your campers 30A cord in. That's a no-no. If you do use an extension cord, it should be a 12g cord and no longer than 25'. If you use a long, light weight extension cord, you could experience a voltage drop even if you are on 30A service (15A service has nothing to do with your voltage loss). Running the AC on less than 105V could damage your AC unit.

How old is your AC? How far is it from your camper to where you plug into your house?

[wavery]

What is your electricity source?  From what I've read, the 15 amp service at home isn't enough to power the A/C unit to full capacity.  That only comes with 30 amp service.  When I tried my A/C unit at home, it barely got cool.  When I tested it at the dealer when I picked it up (plugged in to 30 amp service), it got cold within minutes.

Camp&Fish,

If you are experiencing a voltage drop when plugged into your house's 15A service, you may have a problem in your house wiring. This should not happen unless you are using an extension cord.

Your house service should supply 15A at 110V. That should be sufficient to run most camper AC units (but not all). If the AC pulls more than 15A, it should blow the circuit breaker but it should not drop below 110V. If it is delivering below 110V without blowing the breaker, that's an indication of a wiring problem in the house or using an extension cord.

[magnmike]

I'd try the test again when it's a little warmer.

Try sticking your thermometer in the AC duct of your car. That will give you an idea of what you should have. You may not get 40 degrees, like your car does (should) but it should be close. High 50's seems a bit high to me.

15A service should run your AC just fine. If it draws too much, it will pop the circuit breaker. To be certain, check the voltage in one of your campers outlets while the AC is running. If it's 110V+, you're doing fine. If it is below 105V, you could have a problem. That is usually due to using an extension cord to plug your campers 30A cord in. That's a no-no. If you do use an extension cord, it should be a 12g cord and no longer than 25'. If you use a long, light weight extension cord, you could experience a voltage drop even if you are on 30A service (15A service has nothing to do with your voltage loss). Running the AC on less than 105V could damage your AC unit.

How old is your AC? How far is it from your camper to where you plug into your house?

This afternoon is was about 85 outside.  Inside the pop up (without air on) it was 90.  I turned air back on and just let it run.  When I would check on it with compressor running it read about 50 degrees.  In about an hour or so, it had cooled down to 70 degrees in the popup.  

I have it in the driveway with main camper power cord plugged directly into outside house 110 outlet (using the plug adapter).  Air Conditioner is plugged directly into outlet rated for air in the popup.  I assume the air conditioner is original (2000 Coleman Mach unit).  No extension cords.

[wavery]

This afternoon is was about 85 outside.  Inside the pop up (without air on) it was 90.  I turned air back on and just let it run.  When I would check on it with compressor running it read about 50 degrees.  In about an hour or so, it had cooled down to 70 degrees in the popup.  

I have it in the driveway with main camper power cord plugged directly into outside house 110 outlet (using the plug adapter).  Air Conditioner is plugged directly into outlet rated for air in the popup.  I assume the air conditioner is original (2000 Coleman Mach unit).  No extension cords.

If it's cooling the PU down to 70 with an 85 outside temp, I'd say it's doing pretty good.

50 at the evaporator is not ideal but it's not bad. Sounds like the thermostat system is OK. It could be a little low on freon but it's not worth trying to fix that.

BTW......I forgot to tell you. You should check the temp with the thermo on the lowest temp setting and the fan on low. That slows the air down passing through the evap core and gives it more time to cool.

Did you happen to check the voltage in the outlets in your camper??

[magnmike]

Haven't checked the outlets yet.  So I should put on lo cool or low fan with temp dial still all the way in the blue right and check it that way?  Does that mean that lo cool will actually cool more efficiently because it is not blowing the air as fast?
Thanks for all of your help!

[coach]

With outside temp over 80 and air conditioner running, measure the return (intake) air temp and the supply (output) air temp in the PU near the air conditioner. Determine the difference (70-50), 20 degrees F is great, 15 is good, less than that is not so good!

The air temp coming out of the air conditioner may be cooler when the fan is slowed but there will be much less cool air and therefore less overall cooling of the PU.

Turn the lights off and you'll feel cooler also!

Automobile air conditions put out much cooler air than a 'normal' air conditioner. They are designed to since most have a bunch glass and plenty of horsepower (or is it torque) to run.

[wavery]

Coach is right. You want the temp setting on the thermostat at it's lowest temperature setting and fan on low for testing. This will give you your coldest temp at the evaporator core. However, the same reason that causes the lowest temp at the core makes it less efficient for actually cooling the camper.

What you must remember about air conditioning is that you are NOT adding cold....you are removing heat. Once you understand that fact, you will better understand that the best way to remove the heat is to circulate the inside air over and over, having that air pass over the cold evaporator coils as fast as possible and discourage the introduction of outside air and the loss of the cooler inside air.

The slower moving air over the evap core causes the air to be colder because it has more exposure to the cold coils and more heat is removed. However, more heat is being removed from a much lower volume of air making it less efficient for cooling the entire room.