Air Conditioner Hazard Potential - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 


Like Tree3Likes
Reply
 
LinkBack Thread Tools
  #1  
Old 11-23-2013
svHyLyte's Avatar
Old as Dirt!
 
Join Date: Nov 2008
Location: Tampa Bay Area
Posts: 2,713
Thanks: 13
Thanked 104 Times in 99 Posts
Rep Power: 6
svHyLyte is on a distinguished road
Air Conditioner Hazard Potential

This past week we had an unfortunate experience with our AC system that others might want to know of. Essentially, because of a failed cable tie, the 3-lead power cable to the fan assembly came in contact with the very small copper tube that directs hot compressed gas from the compressor to the heat exchanger. Some may be surprised to learn, as was I, that the temperature of that gas line can be great enough to melt the plastic insulation on a power cable and, in our case, did. With that, the copper tube itself acted as a conductor connecting the hot lead in the cable to the ground lead, which activated the fan even when the AC system was "off" (so long as power was supplied to the AC circuit).

I discovered the issue when I arrived at the boat and found the AC fan running even though the AC system was off. Originally I thought there was a defect in the control module on the circuit board but, after a technician from the manufacturer swapped out the board, the problem continued, indicating a short circuit. A careful, tedious, inspection of the wiring finally revealed the damaged cable that was shorting out. Fortunately, the cable was easily enough repaired and wiring re-secured (with better cable ties), and the position of the tube to the heat exchanger re-aligned somewhat to prevent a possible repeat. Moreover, although our system is "out of warranty", the manufacturer waived any charges for the service call (which took rather a good deal of time and included a new circuit board in the control module) declaring that the problem "..should not have happened".

N'any case, for those with air conditioning, one might want to know of the potential issue and might want to double check one's own wiring where movement of the yacht over time might wear on wire and cable ties.

FWIW...
zeehag likes this.
__________________
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
Reply With Quote Share with Facebook
  #2  
Old 11-23-2013
AllThumbs's Avatar
midlife crisis member
 
Join Date: Jul 2008
Posts: 969
Thanks: 0
Thanked 9 Times in 8 Posts
Rep Power: 7
AllThumbs is on a distinguished road
Re: Air Conditioner Hazard Potential

It's hard to believe that the "hot wire to copper pipe" resulted in the motor running continuously. You would think it would result in a short circuit and blown fuse or breaker.
__________________
I sail.
Reply With Quote Share with Facebook
  #3  
Old 11-23-2013
svHyLyte's Avatar
Old as Dirt!
 
Join Date: Nov 2008
Location: Tampa Bay Area
Posts: 2,713
Thanks: 13
Thanked 104 Times in 99 Posts
Rep Power: 6
svHyLyte is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by AllThumbs View Post
It's hard to believe that the "hot wire to copper pipe" resulted in the motor running continuously. You would think it would result in a short circuit and blown fuse or breaker.
The tubing merely fulfilled the function that a closed switch would have served. In operation, the fan pulled only a few amps.
__________________
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
Reply With Quote Share with Facebook
  #4  
Old 11-23-2013
deniseO30's Avatar
Move over Joan Rivers!
 
Join Date: Nov 2006
Location: Bristol pa
Posts: 6,145
Thanks: 52
Thanked 89 Times in 79 Posts
Rep Power: 9
deniseO30 will become famous soon enough deniseO30 will become famous soon enough
Re: Air Conditioner Hazard Potential

Omph... glad the line didn't short enough to make a burn hole in the tube. Loosing the charge and having the line brazed then replacing filter dryer, evacuate and recharge would not have be fun to pay for. Nice Save SVH!
__________________
Denise, Bristol PA, Oday 30. On Tidal Delaware River, Anchor Yacht Club. New Website!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

my current "project"!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #5  
Old 11-23-2013
AllThumbs's Avatar
midlife crisis member
 
Join Date: Jul 2008
Posts: 969
Thanks: 0
Thanked 9 Times in 8 Posts
Rep Power: 7
AllThumbs is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by svHyLyte View Post
The tubing merely fulfilled the function that a closed switch would have served. In operation, the fan pulled only a few amps.
Understood, but usually an appliance is grounded such that the breaker would trip as soon as the hot wire's insulation is compromised and the conductor makes contact with any metal part of the equipment. It sounds like you may still have an issue with the appliance. It sounds like the equipment ground (green) is not connected. This is very hazardous as it could cause someone to be electrocuted.
__________________
I sail.
Reply With Quote Share with Facebook
  #6  
Old 11-24-2013
svHyLyte's Avatar
Old as Dirt!
 
Join Date: Nov 2008
Location: Tampa Bay Area
Posts: 2,713
Thanks: 13
Thanked 104 Times in 99 Posts
Rep Power: 6
svHyLyte is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by AllThumbs View Post
Understood, but usually an appliance is grounded such that the breaker would trip as soon as the hot wire's insulation is compromised and the conductor makes contact with any metal part of the equipment. It sounds like you may still have an issue with the appliance. It sounds like the equipment ground (green) is not connected. This is very hazardous as it could cause someone to be electrocuted.
I appreciate the observation and I shall put a call in to our AC manufacturer about this to be sure but I believe the short was between the white and black leads in the cable itself and I do not know if the case of the compressor from which the tube originated is, itself, connected to the neutral ground. (Unfortunately, my knowledge of matters electrical is rather sparse.)
__________________
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
Reply With Quote Share with Facebook
  #7  
Old 11-24-2013
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,425
Thanks: 1
Thanked 27 Times in 25 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: Air Conditioner Hazard Potential

I am assuming that it was a 12v fan circuit that shorted. The only way I could see such a short to cause the fan to run continuously would be if the system was switching the negative to bring the fan on, and the negative was the compromised conductor. If it was the "hot" lead that shorted it certainly should have blown a fuse.
For what it's worth, under normal circumstances the discharge line of an a/c system should not get hot enough to melt insulation. More likely the damage would have been caused by chaffe. If the circuit had been 110v it probably would have blown a hole in the discharge line and dumped the charge.
Minnewaska likes this.
__________________
1979 Santana 30 Tall Rig
Hull#101
Reply With Quote Share with Facebook
  #8  
Old 11-24-2013
ebs001's Avatar
Senior Member
 
Join Date: May 2006
Location: Ottawa, Canada
Posts: 2,132
Thanks: 5
Thanked 21 Times in 19 Posts
Rep Power: 9
ebs001 is on a distinguished road
Re: Air Conditioner Hazard Potential

The power to an A/C is 120 volts and powers both the fan and the compressor. The control circuit which turns the unit on is typically 24 volts. With an A/C only unit there are three wires from the thermostat to the A/C unit - power, compressor, and fan. If the tubing connected the power to the fan unit, the fan would run constantly. The control circuit is not grounded and so no short circuit would occur.
Reply With Quote Share with Facebook
  #9  
Old 11-24-2013
SchockT's Avatar
Senior Member
 
Join Date: May 2012
Location: North Vancouver, BC
Posts: 1,425
Thanks: 1
Thanked 27 Times in 25 Posts
Rep Power: 3
SchockT is on a distinguished road
Re: Air Conditioner Hazard Potential

Quote:
Originally Posted by ebs001 View Post
The power to an A/C is 120 volts and powers both the fan and the compressor. The control circuit which turns the unit on is typically 24 volts. With an A/C only unit there are three wires from the thermostat to the A/C unit - power, compressor, and fan. If the tubing connected the power to the fan unit, the fan would run constantly. The control circuit is not grounded and so no short circuit would occur.
I would be curious to see a wiring diagram for the unit, and see which conductor was shorted out. Regardless of the voltage, the only way the short could have caused the fan to run is if the motor is supplied with a constant 120v hot, and they are switching the neutral to cycle the fan on and off. If it was indeed a 110v HOT lead that contacted the refrigerant piping and the breaker did not trip then the unit wiring is in a very unsafe condition.

The OP stated that the cable that was damaged was the 3-lead power cable to the fan assembly. If he was mistaken, and it was actually the 24v thermostat wire that shorted between R and G then the fan would run continuously, however, if the R wire contacted the refrigerant piping it still should have blown the control fuse because the control transformer should be connected to the same ground as the rest of the unit.

Of course the marine industry seems to do some pretty goofy things with electrical, so I guess goofy things can happen as a result....
__________________
1979 Santana 30 Tall Rig
Hull#101

Last edited by SchockT; 11-24-2013 at 06:38 PM.
Reply With Quote Share with Facebook
  #10  
Old 11-24-2013
ebs001's Avatar
Senior Member
 
Join Date: May 2006
Location: Ottawa, Canada
Posts: 2,132
Thanks: 5
Thanked 21 Times in 19 Posts
Rep Power: 9
ebs001 is on a distinguished road
Re: Air Conditioner Hazard Potential

We are not talking a short here but a closed circuit on the control side. The control wire closes the fan relay and the fan will then get constant power just the same as switching the fan switch to on on the thermostat. Short circuits cause breakers to trip not fans to run. 24 volt control circuits do not have fuses nor is the control transformer grounded on the load side.

The neutral is never switched.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Air conditioner questions saillife Gear & Maintenance 6 08-13-2010 02:49 PM
Paint in the Air Conditioner labestia Gear & Maintenance 3 06-29-2009 09:16 AM
Recommissioning Air Conditioner mgmhead Gear & Maintenance 8 06-09-2009 11:45 PM
Smoke from air conditioner dohenyboy Gear & Maintenance 7 07-28-2007 11:11 PM
Air Conditioner randall2v Gear & Maintenance 0 06-30-2004 01:39 PM


All times are GMT -4. The time now is 01:51 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.