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-   -   Trane XE90 pressure switch problem (http://www.houserepairtalk.com/f8/trane-xe90-pressure-switch-problem-14845/)

incarmel 10-03-2012 10:50 PM

Trane XE90 pressure switch problem
 
Got 3-flash code for pressure switch problem on my trane xe90 system (~15 year old).
The inducer fan runs with normal sound. Can see the turning of fan.
Opened the front tube to pressure switch and saw water dripping out. Dirty brown rusty water also came out of the front hole on the pressure switch.
Opened the back tube to pressure switch. Can feel air coming out of this tube but don't know the pressure.
I suspect the pressure switch is dead.
Any suggestions for this issues?

Thanks.

Wuzzat? 10-04-2012 10:24 AM

Get the specs for the switch and simulate the setpoint pressure by using a column of water. You'll need some tubing from the hardware store, and a meter.

If it's like 0.05" WC [about 3/64"] you may want to put a drop of hand dishwashing liquid in the water. It breaks the surface tension so you get a more accurate reading.
Or you can slope the tubing which will amplify how visible this 3/64" is. A 10 degree slope will give you a 17/64" difference.

From Grainger, roughly half of their switches cost between $44 and $26.

kok328 10-04-2012 05:58 PM

clean the openings on the inducer motor where the tubes connect & check the exhaust pipe for wasps/bees nest looking for any blockage that may prevent the pressure switch from "making".

incarmel 10-05-2012 06:44 PM

Quote:

Originally Posted by kok328
clean the openings on the inducer motor where the tubes connect & check the exhaust pipe for wasps/bees nest looking for any blockage that may prevent the pressure switch from "making".

My contractor just extended the exhaust pipe to ~9" tall. I assume it is clean inside.

The inducer motor/drain tube are also clear.

incarmel 10-05-2012 06:46 PM

Quote:

Originally Posted by Wuzzat?
Get the specs for the switch and simulate the setpoint pressure by using a column of water. You'll need some tubing from the hardware store, and a meter.

If it's like 0.05" WC [about 3/64"] you may want to put a drop of hand dishwashing liquid in the water. It breaks the surface tension so you get a more accurate reading.
Or you can slope the tubing which will amplify how visible this 3/64" is. A 10 degree slope will give you a 17/64" difference.

From Grainger, roughly half of their switches cost between $44 and $26.

Ordered a new switch and will arrive tomorrow. Will update.

Update:
My new pressure switch arrived.
Put it to replace the old one.
The furnace back to work.

Thank you guys for the help.


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