Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 

Go Back   Keystone RV Forums > Keystone Tech Forums > Technical Corner
Click Here to Login

Reply
 
Thread Tools Display Modes
 
Old 05-15-2016, 07:55 AM   #1
ksstick
Junior Member
 
Join Date: Mar 2014
Location: Iowa
Posts: 7
AC Vent Temps 15 BTU Dometic

Hello
My Ac doesn't seem to be working properly
The temperature at the vents are only 60 degree and outside temp was 74 degrees
Yes at the vents and AC are clean?
Can I assume it is low on Freon? I was told most places don’t work on the AC unit, just replace them.
Any thoughts?
ksstick is offline   Reply With Quote
Old 05-15-2016, 08:17 AM   #2
canesfan
Senior Member
 
canesfan's Avatar
 
Join Date: Jan 2014
Location: Tidewater Area Virginia
Posts: 1,271
RV AC units are "closed" systems (although some will argue that point) and because of that you can't add freon, if, in fact, that is what is wrong. I don't know what temp the air coming out of the vents "should" be.
__________________
2014 Raptor RP300MP w/ Rear Patio Party Deck, Folding Side Ladder, 6 Point Level Up, Carlisle Radial Trail HDs
2004 2500HD D/A CC SB - TTT Mirrors, Prodigy BC, 18K Pullrite Superglide, NEW Fuel Injectors 11/2015 (ouch)
canesfan is offline   Reply With Quote
Old 05-15-2016, 08:25 AM   #3
Bob Landry
Senior Member
 
Join Date: Jan 2011
Location: Austin, Tx
Posts: 1,910
First of all, outside ambient temp is irrelevant to determining proper AC operation. The fact to observe is the "split across the coil", IE temperature difference between the return air and discharge air. A difference of 18-20 degrees indicate proper cooling. This figure can be misleading if the unit has dirty filters which would restrict air flow or is simply undersized for the space it's cooling. So this number is really only valid if everything is as it is supposed to be.
A temperature measurement directly at the supply air output of upper 50s to 60 degrees would indicate a properly functioning unit. If you go on top and remove the AC shroud, the suction line sweating back to the compressor would also indicate that the unit is properly charged. Charge can also be checked by measuring the compressor amp draw and that has been discussed in previous threads.
If you are reading 60 degrees at your vents, and the trailer is not being cooled, your unit is probably undersized. I would also check the plenum, and vents for leaks that may be pumping air into your ceiling.
__________________
2011 Outback 277RL
2013 F250 XLT Crew Cab 6.2L

Bitter Gun Owner
Bitter Clinger
Armed Infidel
Bob Landry is offline   Reply With Quote
Old 05-15-2016, 10:16 AM   #4
Ken / Claudia
Senior Member
 
Join Date: Nov 2012
Location: Fruitland
Posts: 3,357
I agree with Bob, the a/c units are made to reduce the air they intake by 20 degrees F at best. Even the Keystone manual as lacking as it is lists that information.
__________________
2013 24RKSWE (27ft TT) Cougar 1/2 ton series SOLD 10-2021
2013 Ford F350 4x4 CC 6.7 engine, 8 ft bed, 3.55 rear end, lariat package
Retired from Oregon State Police in 2011 than worked another 9.5 years as a small town traffic cop:
As of 05-2020, I am all done with 39 years total police work. No more uniforms for me.
Ken / Claudia is offline   Reply With Quote
Old 05-15-2016, 01:08 PM   #5
sourdough
Site Team
 
Join Date: Feb 2014
Location: W. Texas
Posts: 17,598
I'm not an AC tech by any means. I have a 2014 Dometic 15k AC. I'm sitting in the panhandle of FL and the outside temp is 87. My ducts read 48 degrees to 51 degrees with an infrared temp gun. Don't know what that really tells you. How old is the unit/ducts/etc. etc.? Maybe it just needs a little TLC.
sourdough is offline   Reply With Quote
Old 05-15-2016, 05:00 PM   #6
dcg9381
Senior Member
 
Join Date: Jul 2015
Location: Texarkana, TX
Posts: 1,052
Quote:
Originally Posted by ksstick View Post
Can I assume it is low on Freon? I was told most places don’t work on the AC unit, just replace them.
Any thoughts?
Yea, for $700 or whatever they cost, they just get replaced. They're pretty easy to replace once you get them on to the roof.

If the compressor is running (you should be able to hear it) and you're only getting a 15 degree temp drop over the coils, something is wrong...
dcg9381 is offline   Reply With Quote
Old 05-15-2016, 06:03 PM   #7
JRTJH
Site Team
 
JRTJH's Avatar
 
Join Date: Mar 2011
Location: Gaylord
Posts: 26,836
Quote:
Originally Posted by ksstick View Post
Hello
My Ac doesn't seem to be working properly
The temperature at the vents are only 60 degree and outside temp was 74 degrees
Yes at the vents and AC are clean?
Can I assume it is low on Freon? I was told most places don’t work on the AC unit, just replace them.
Any thoughts?
The Air Conditioner is warrantied for 2 years. If I remember correctly, this month will be your second anniversary, so if you're having issues with your A/C, I wouldn't delay contacting your dealer and getting his advice about whether or not you can get warranty service before it expires!!!!!
__________________
John



2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
JRTJH is offline   Reply With Quote
Old 05-15-2016, 07:10 PM   #8
ksstick
Junior Member
 
Join Date: Mar 2014
Location: Iowa
Posts: 7
the suction line back to the compressor is freezing up
ksstick is offline   Reply With Quote
Old 05-15-2016, 07:45 PM   #9
chuckster57
Site Team
 
chuckster57's Avatar
 
Join Date: Jul 2014
Location: Modesto
Posts: 20,234
There should be a freeze sensor on the coils above the intake. Possible its fallen out/off? Some clip on some just push in between the fins.
__________________

2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.

Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
chuckster57 is offline   Reply With Quote
Old 05-16-2016, 09:05 AM   #10
Bob Landry
Senior Member
 
Join Date: Jan 2011
Location: Austin, Tx
Posts: 1,910
Quote:
Originally Posted by ksstick View Post
the suction line back to the compressor is freezing up
I would look for an air restriction, either dirty filters or a dirty evaporator. It could be a low charge, but the frequency of that happening on these units is low and they only take a pound or so of refrigerant, so if you do develop a leak, you would most likely lose the entire charge and there would be no cooling at all.
You have no way of checking for a correct charge except to measure the amp draw of the compressor and Dometic is going to require the shop to do that before replacing it under warranty.
__________________
2011 Outback 277RL
2013 F250 XLT Crew Cab 6.2L

Bitter Gun Owner
Bitter Clinger
Armed Infidel
Bob Landry is offline   Reply With Quote
Old 05-16-2016, 09:12 AM   #11
Bob Landry
Senior Member
 
Join Date: Jan 2011
Location: Austin, Tx
Posts: 1,910
Quote:
Originally Posted by sourdough View Post
I'm not an AC tech by any means. I have a 2014 Dometic 15k AC. I'm sitting in the panhandle of FL and the outside temp is 87. My ducts read 48 degrees to 51 degrees with an infrared temp gun. Don't know what that really tells you. How old is the unit/ducts/etc. etc.? Maybe it just needs a little TLC.
An infrared gun is not going to tell you much. The outside temp is irrelevant since all of the air going through the coil is recirculated from inside. It doesn't draw in any outside air. The reading from the IR gun is affected by several variables. The size of the dot projected by the gun varies in accordance with the distance, it depends on exactly where on the unit you are reading, and most IR guns have a margin of error, usually up around 5%, so it is of little if any benefit for troubleshooting/checking ACs or refrigerators. It does an adequate job of checking for overheated axle spindles.
__________________
2011 Outback 277RL
2013 F250 XLT Crew Cab 6.2L

Bitter Gun Owner
Bitter Clinger
Armed Infidel
Bob Landry is offline   Reply With Quote
Old 05-16-2016, 09:48 AM   #12
sourdough
Site Team
 
Join Date: Feb 2014
Location: W. Texas
Posts: 17,598
As far as literal AC function I understand the outside temp is irrelevant, but, from a practical standpoint the outside has a lot to do with how the AC cools. Our black vent covers, AC shrouds, black windows etc. generate a ton of heat inside of the trailer; all of which the AC has to counter - the hotter it is the harder it has to work. At some point an x sized AC will not cool an x sized trailer simply due to the amount of heat coming into the unit and the limitations of the AC unit.....then you get a larger unit or 2nd AC Simplified I understand but those are factors.

At 50 degrees a +/- of 5% (2.5 degrees) is good enough for me with the infrared gun. It's also good enough for my heating/cooling contractor to use when diagnosing AC problems. The gun says its optimum reading range is 18" and that's what I used when reading the AC vents in the trailer. I do also use it for reading my wheels when traveling....much more accurate than putting my hand on the wheel/tire It's just a good way to get a quick indicator of what's going on; beats the heck out of hanging little thermometers in the vents, waiting for them to get to max cool and then trying to read them as I've seen done.
sourdough is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by the Keystone RV Company or any of its affiliates in any way. Keystone RV® is a registered trademark of the Keystone RV Company.


All times are GMT -8. The time now is 01:08 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.