Ignoramus12834 wrote:
On Sat, 26 Nov 2005 15:52:36 GMT, Pete C. wrote:

This delusion of the PYVs (plastic yuppie vermin) is furthered by the
increasing complexity of cars and the thought that the grease monkeys
couldn't possibly understand anything about computers so they must just
be swapping parts until things magically start working.


They keep swapping parts because it makes them money.

A true story. A couple of years ago, a lightning struck a big tree in
our yard:

http://igor.chudov.com/tmp/lightning/

That also knocked out our central A/C.

So, I went in with a multimeter and tried tracing just where does not
signal go etc. I learned that the control board was sending proper
signal to the motor drive board, etc.

Then we called an A/C guy. He calls me at work and says stuff like
"the main board is probably knocked out and needs replacement", lets
replace this and that etc.

I asked him just what basis do you have for saying so. (because I knew
that it was bull****). He mumbled some nonsense. I decided not to hire
him, although I paid his visit fee. I did not feel like hiring someone
who is either incompetent or a crook. I called another A/C company and
explained them my findings etc.

He replaced the motor drive board, it was covered by warranty (but
labor was not), and everything works fine to date. Some other things
failed since, such as quick disconnect terminals fell apart on the
main contactor, but the control system is fine.

The moral of the story, they want replacing parts because it makes $$
for them.

i


The moral of the story is that you are PYV. All the electronic boards
are LRUs in the mechanical trades and there is no way that repair could
be cost effective any other way, parts are way below labor costs. In the
case of a lightning strike where one board has failed, it is good
practice to yank *all* of them and be done with it. You are getting
*new* boards at reasonable markup, you pay a single labor charge, and
there is no possibility of less than a durable fix or additional damage
being done due to faulty drive. I can see the HVAC tech breaking out the
oxy-acetylene torch to solder components...too funny.