Another AC question, it must be summer

[adonh]

What a beautiful spring we had here in the Houston TX area at least for a few weeks, mild days with low humidity. But summer is here now, 90+ degrees and high humidity. Here is my AC question concerning my 6 year old Dometic Penguin 13,500 BTU units. At peak operating conditions or say when new with the thermostat set to max cold on a hot 92 degree humid day. What should the temperature range be coming out of the vent. Not the actual temp inside but the coldest air just as it comes from the vent.

On mine its around 74 degrees and interior of the coach does not get very cool.

Thanks

[Indy1951]

Both the outdoor temp and the temp inside the coach have an effect on the discharge temp of the A/C. With that said being low on refrigerant and dirty coils will also have an effect. There is no set answer on discharge temp.

[CLIFFTALL]

I seem to remember that a 20 degree variance is about right.

[adonh]

Originally Posted by Clifftall

I seem to remember that a 20 degree variance is about right.

That is what I have heard as well, so at 92 outside you could expect the inside temp to settle in at around 72 to 75 degrees. But to achieve this the air just as it comes out the vent would need to be in mid 60 degree range since it starts to warm as soon as it passes into the interior space. I am at around 74 degrees when it comes out the vent and around 82 on the actual interior temp. At night with lower outside temp it cools fins as well as in the morning hours until the sun gets high. So what is the diagnosis of the unit, low coolant, dirty coils, thermostat, bad compressor, any thoughts.

Thanks

["007"]

You may need some cleaning of your AC. on a cool day.

[CampDaven]

I had a 23 ft C with a 13.5K btu unit. At 95, it took a looong time to catch up, but it did. About 3-4 hours. It was much worse before I cleaned it.

[adonh]

Originally Posted by 007";1580448]You may need [URL="http://www.irv2.com/forums/f103/penguin-13-5-to-15k-upgrade-99090.html#post928292

some cleaning of your AC.[/URL] on a cool day.

Great detailed instructions, thanks.

[jesilvas]

There are set temperatures for the intake/exhaust delta.
15 is minimum, should be 20.
Had a horse trailer with a 13.5 Coleman, only with a 12*F swap. Dirty coils. Cleaned coils. Didn't help it.
At that point, test compressor amp draw. If it's lower than the rating adjusted for temp, you're low on refrigerant.

[ruffian]

AC's generally work on a 20 deg. differential. Measure the air temp as it enters your AC inside the coach. If for example it is 80 deg, the air exhaust temp should be around 60 deg. From this point there are many variables effecting how quickly, if at all, your coach interior will cool.

As your coach air cools to 79, then the outlet air will be 59. Eventually, hopefully your coach interior will reach a comfortable temp.

[bruceisla]

Originally Posted by ruffian

AC's generally work on a 20 deg. differential. Measure the air temp as it enters your AC inside the coach. If for example it is 80 deg, the air exhaust temp should be around 60 deg. From this point there are many variables effecting how quickly, if at all, your coach interior will cool.

As your coach air cools to 79, then the outlet air will be 59. Eventually, hopefully your coach interior will reach a comfortable temp.

For reference, while working on my A/C problem, outside air temp was 85, after 45 minutes of running A/C the inside coach temp was 69, the air temp 6 inches INSIDE the output ductwork was 47. Measured with infrared gun.

Here was my problem:
http://www.irv2.com/forums/f54/a-c-d...ab-162093.html

[TXiceman]

Infrared temp sensors a generally not that accurate for reading the air temp. You need to use a thermometer as close to the inlet as possible and as close to the unit fro the outlet. The fan and unit need to be running on high for at least 15 minutes. The temperature difference should be 18 to 20 degF. More of less could be a problem.

When was the last time you cleaned the filters and also cleaned the evaporator coil?
Also if a ducted unit, check the dusts and unit connections for leakage.

Ken

[adonh]

Originally Posted by bruceisla

Here was my problem:
http://www.irv2.com/forums/f54/a-c-d...ab-162093.html

Nice job really looks good. It looks like you completely remade the cover over the evaporator coils and blower and resealed everything. What was the material that you used. I am going to check my duct work as well and pull the cover and clean the coils and check thing out. Did clean the coils as well. If so what type of coil cleaner if any did you use.

Thanks

[bruceisla]

Originally Posted by adonh

Nice job really looks good. It looks like you completely remade the cover over the evaporator coils and blower and resealed everything. What was the material that you used. I am going to check my duct work as well and pull the cover and clean the coils and check thing out. Did clean the coils as well. If so what type of coil cleaner if any did you use.

Thanks

Hi Don, kept the original sheet metal cover and used 3M spray adhesive to attach 2 layers of Reflectix (both layers on the top side of cover). Also filled small areas on side with Reflectix. I didn't use coil cleaner ... used a soft brush until no dirt came off. Actually, it wasn't very dirty. The upper unit changes made a minor difference of about 2-3 degrees. The biggest difference was the inside ducts and airboxes.

[adonh]

Originally Posted by bruceisla

Hi Don, kept the original sheet metal cover and used 3M spray adhesive to attach 2 layers of Reflectix (both layers on the top side of cover). Also filled small areas on side with Reflectix. I didn't use coil cleaner ... used a soft brush until no dirt came off. Actually, it wasn't very dirty. The upper unit changes made a minor difference of about 2-3 degrees. The biggest difference was the inside ducts and airboxes.

I am going to tackle my tomorrow morning. I will post pictures and details on what I find.