Old as Dirt!
Join Date: Nov 2008
Location: Tampa Bay Area
Thanked 131 Times in 124 Posts
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Re: Air Conditioner Hazard Potential
Firstly, thanks for the interest. Secondly, keep in mind that I am "challenged" in matters electrical so my use of terminology or descriptions may leave something to be desired. N'any case, to clarify, the power cable to the fan assembly is 120v. The green wire in that cable is connected to the fan assembly on one end, and to a neutral green bus board on the Air Conditioner ("AC") controller circuit board. The black and white wires in that cable are connected to either side of a variable voltage relay (kind of a digital rheostat) on the circuit board in the control module that, depending upon the difference between the ambient air temperature and the thermostat setting, varies the fan speed from very slow (when there is little temperature difference) to full bore (when there is a 10º or greater difference). The 1/8" dia (or so) compressed gas line that melted the insulation (and one of my slip neighbors, a mechanical engineer who owns a sizable AC contracting firm assures me that such a line can get hot enough to melt insulation) merely acted to complete the circuit between the black and white wires in the cable, activating the fan, just as the switch on the circuit board does/would when it is enabled. (I believe there is a separate "hot" red colored lead to the fan assembly as well.)
The air conditioning system on our boat is identical to its predecessor, which we had for 16+ years, in all respects save for the control module which is now digital verses the earlier analog system--i.e. manual controls of fan speed, heat or cooling selection, etc. (Frankly I prefer the old arrangement to all of this digital BS). The old unit worked extremely well so when it died of old age, we replaced it with it's newer, supposedly more up-to-date sibling.
The power cable to the fan assembly came in contact with the hot coolant tube because of the failure of a wire tie that was used to route the cable around and past the compressor assembly; and, because the coolant tube was not enclosed in an insulating cover (although my slip neighbor indicated that wasn't unusual either). The foregoing, and the compactness of the system which brings potentially conflicting mechanisms in close proximity to one another gave rise to our problem. The make of the machine is irrelevant as I have since observed the same proximities and prospective conflicts/hazards in two other systems, made by two other, different, manufacturers, while helping neighbors check their systems as I suggested others do of theirs in my original post. And, the builder of our machine is issuing a technical bulletin on the matter that is being sent to the owners and installers that handle its machines so that corrective/preventive measures and be taken, if necessary. I am afraid naming the manufacturer would simply cast it in an undeserved bad light, which I prefer not to do, especially considering the lengths the company went to helping me resolve the issue at no charge and with only moderate inconvenience.
Addendum: Since posting the above message I have learned that the red wire referred to in the parenthetical phrase at the end of my first paragraph, above, has nothing to do with the operation of the fan and is merely coincidental to the 3-lead power cable. Please see my follow-up post, #20, below.
"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."
Last edited by svHyLyte; 11-25-2013 at 04:04 PM.
Reason: Add addendum; add second addendum