Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-07-2010, 01:21 PM   #1
Newbie
 
Join Date: Apr 2010
Posts: 5
Rewards Points: 0
Share |
Default

Rapid on/off cycling of outdoor compressor


Hi, I'm new to this forum. I'm hoping the pro's who are here may be able to answer my question.

Last night the AC was on and running fine when we went to bed. It was not on this morning when we got up, but that is normal since the building cools down on its own during night time, and the AC isn't needed.

Well, I had been noticing that the line set that was installed new about 3 years ago (and is in the crawl space) seemed to be transmitting noise from the compressor through the line set up to the floor of the kitchen, which is mainly what the line set runs under. So, I went down and found the line set resting on top of a copper water pipe, placed a plastic hanger strap around the line set, and attached the strap to the floor joist just above. In the process, I raised the line set about 3/8" to 1/2" above the pipe. When I turned on the AC later to check things, the compressor immediately started but within a few seconds, shut off. It then started within several seconds, ran for a few seconds and shut down. After about 3 cycles like that, I turned the system off, went down and removed the just installed strap, and tried again. The same cycling occurred. The fan above the compressor also runs and shuts down the same as the compressor.

So, did I disturb something by raising the line set that fraction of an inch? If so, will things just work out after 30 seconds, or so? Or is it just a coincidence and maybe the AC shut down last night anyway but was not known to us that it did so? If so, what's likely really going on here?

Thanks,
Dave

Dave66 is offline   Reply With Quote
Old 04-07-2010, 03:36 PM   #2
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,420
Rewards Points: 60
Default

Rapid on/off cycling of outdoor compressor


If you raised the lineset and disturbed it and it sprung a freon leak then the unit may be cycling on the low pressure control. Sounds like you need a Pro to check the freon level. The leak may be from earlier and this is coincidental you moving the line.

__________________
"Cut it twice and it is still too short".
yuri is offline   Reply With Quote
Old 04-07-2010, 04:59 PM   #3
Newbie
 
Join Date: Apr 2010
Posts: 5
Rewards Points: 0
Default

Rapid on/off cycling of outdoor compressor


Yuri, thank you for your post. I have to call the dealer to do the spring AC checkup anyway, so I will just call him sooner rather than later (normally in May). Thinking about my possibly causing a leak (the system uses R410A), wouldn't I have heard the sound of pressure being released down there in the crawl space similar to what I've seen/heard when freon was accidentally leaked outside?

Since my first post, I've looked at the AC install manual and checked the outdoor unit for fault codes. It shows a code 4 (4 blinking yellow lights) that means "locked rotor", which does not seem to apply here. Strange, huh?
Dave66 is offline   Reply With Quote
Old 04-07-2010, 05:07 PM   #4
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,420
Rewards Points: 60
Default

Rapid on/off cycling of outdoor compressor


Locked rotor is NOT good. Means that it is seizing or broken inside. Needs to be checked by the Pro.
__________________
"Cut it twice and it is still too short".
yuri is offline   Reply With Quote
Old 04-07-2010, 06:03 PM   #5
Newbie
 
Join Date: Apr 2010
Posts: 5
Rewards Points: 0
Default

Rapid on/off cycling of outdoor compressor


I'm probably not understanding the meaning or significance of a "locked rotor". Isn't the rotor inside the compressor? Can the rotor still rotate if it is "locked"? The compressor sounds normal to me for those seconds when it was actually "running".

Could the locked rotor have been caused by my raising the line set a half inch?
Dave66 is offline   Reply With Quote
Old 04-07-2010, 07:05 PM   #6
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,420
Rewards Points: 60
Default

Rapid on/off cycling of outdoor compressor


Locked rotor means the compressor is unable to turn or turns then jams or locks into something. Broken scrolls or valves or other moving parts could be loose/damaged/colliding and "locking it up". Hard to believe it had something to do with what you did. Or your diagnostic board is giving a false reading. What is the brand and model # of the unit. Locked rotor is usually when it senses a very high current draw. There is LRA locked rotor amps rating on the unit and when it senses that high current draw it thinks the rotor is locked/stuck. After that it generates a LOT of heat and will trip the main breaker or the internal heat overload inside the compressor. Don't keep trying to restart it or that overload may trip and it takes 6 hrs or more to reset plus further damage is occurring to the compressor.
__________________
"Cut it twice and it is still too short".

Last edited by yuri; 04-07-2010 at 07:09 PM.
yuri is offline   Reply With Quote
Old 04-07-2010, 09:31 PM   #7
Newbie
 
Join Date: Mar 2010
Location: Ontario, Canada
Posts: 20
Rewards Points: 0
Default

Rapid on/off cycling of outdoor compressor


It could be as simple as a faulty capacitor. It's very easy and inexpensive to replace.




Last edited by beenthere; 04-08-2010 at 02:58 PM. Reason: Removed link to another forum
User75130 is offline   Reply With Quote
Old 04-08-2010, 07:34 AM   #8
Newbie
 
Join Date: Apr 2010
Posts: 5
Rewards Points: 0
Default

Rapid on/off cycling of outdoor compressor


Quote:
Originally Posted by yuri View Post
Locked rotor means the compressor is unable to turn or turns then jams or locks into something. Broken scrolls or valves or other moving parts could be loose/damaged/colliding and "locking it up". Hard to believe it had something to do with what you did. Or your diagnostic board is giving a false reading. What is the brand and model # of the unit. Locked rotor is usually when it senses a very high current draw. There is LRA locked rotor amps rating on the unit and when it senses that high current draw it thinks the rotor is locked/stuck. After that it generates a LOT of heat and will trip the main breaker or the internal heat overload inside the compressor. Don't keep trying to restart it or that overload may trip and it takes 6 hrs or more to reset plus further damage is occurring to the compressor.
Luri, the outdoor unit is a Luxaire 2 stage model AL5B024F1A and was installed in June 2007. To my untrained ear, the problem didn't sound any different on startup (as described in my original post) than usual. I haven't tried to start it again. The dealer will be out first of the week when the weather warms up again here in west central Indiana.

Thanks again,
Dave
Dave66 is offline   Reply With Quote
Old 04-08-2010, 07:38 AM   #9
Newbie
 
Join Date: Apr 2010
Posts: 5
Rewards Points: 0
Default

Rapid on/off cycling of outdoor compressor


Quote:
Originally Posted by Tech X View Post
It could be as simple as a faulty capacitor. It's very easy and inexpensive to replace.


www.hvactechgroup.com
Thanks, Tech X,

It's nice to know that one of the remedies could be a simple and easy one. It's sure to get checked out by the dealer early next week.

Dave

Dave66 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
what's worse - pump cycling or running continuously? rtoni Plumbing 5 06-18-2012 09:06 PM
Blower cycling and vibration whatshappening HVAC 1 02-09-2010 04:48 AM
Standby generator on/off switch Jeremy Hillary Boob, PhD Electrical 25 10-20-2009 02:16 PM
HVAC Short Cycling Redparis HVAC 2 02-26-2008 10:21 PM
Rapid Water Pressure cycling dwayne Plumbing 2 07-08-2006 08:12 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.