"Tony Hwang" wrote in message
news:gE2mf.74209$Eq5.16556@pd7tw1no...
Bubba wrote:

On Thu, 08 Dec 2005 12:39:25 -0700, MattMika
wrote:


I had a repairman over to look at my furnace yesterday. I was having a
problem where the furnace would not light up everytime it kicked on. It
would start the flue fan but not release gas or light the ignitor when it
failed, other times it would work just fine.

The repairman replaced the pressure switch and said it was working better
already but that there was a problem with the control board as well. I
decided to just have it done(new control board around $260/1yr warranty),
but he didnt have it with him and was supposed to come back today.

I've found the board for $128 online and was wondering if it is very
difficult to install(repairman said it was easy, but he gives 1yr
warranty).

Should I just cancel the board install and see how it goes and install it
myself if it continues to fail or should I just have them do it and get
the
warranty?

The furnace has not failed to function properly since the pressure switch
changeout, but it may just be luck or not enough time for it to have
failed
yet...

Thanks.


I would be "slightly" skeptical. Parts dont usually fail in pairs.
THEY CAN but not usually. You may want to question him why it needs a
new board. You may wish to wait and see if the pressure switch alone
takes care of it. Id wait and see or get another opinion. You can
always get and install the board yourself but as already stated,
you'll get no warranty and you may not even need it.
Good Luck
Bubba
Hi,
Pressure switch is very easy to test. It's simple on/off switch triggered
by diaphragm at certain pressure range. There just could be some dirt or
even drops of water in the air hose. The control board is based on
sequential logic. I went thru whole thing on my Carrier furnace just
before winter. What kind of error code were you getting? This will give a
clue to the cause of the trouble. Lot of times, vibration and heat causes
cracked solder joints on board.
If you really have bad board, it's easy to replace it by just moving wire
harness, plugs one at a time in parallel after turning off power.
Some boards are not exact replacement. It cocmes with instruction and
wiring adapters, etc.
In my case, high Watt resistors on board had poor cooling under the
plastic cover and the excess heat caused solder joint crack. I reinforced
the joints and drilled a few holes on the cover for more air circulation.
Now we're in dead winter and furnace has been working just fine. BTW,
error code I was getting was pressure switch(which does not mean it is
bad. Just it's a clue. Start trouble-shooting from there.
As a retired EE(from Honeywell) I am surprised some HVAC people has very
minimal knowledge of electronics. They create lots of wasted time and
material.
Tony

Tony...when did you retire? Im just curious if Honeywells quality went to
hell before or after.