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-   -   One cold, one not, same plenum, no leak (

minh.nguyen2 08-08-2011 01:57 PM

One cold, one not, same plenum, no leak
2 duct branches from the same plenum give out different air tempurature. One gives out cold air, one is not.

Both airflow is equally sufficient (so there is no leak or blockage, or else it would give discrepancy in airflow). To confirmed, I have checked the trunk itself and found no air leak.

I am baffled, perplexed and beat.


gregzoll 08-08-2011 02:21 PM

Has it always been doing this, has anyone been doing any work on this house, or playing around with the dampers for the duct work?

minh.nguyen2 08-08-2011 02:29 PM

Problem just this summer
No dampers are found along the trunks.
Seems the system only has registers on room ceiling
I just dont get it! if something worng with the unit, then all trunks from the same plenum would be equally effected

Master of Cold 08-08-2011 09:20 PM

What kind of ducting do you have? And how far apart are the vents.
Generally speaking, the vent closest to the unit will be the coldest. The furthest duct is the warmest. The duct system can pick up heat from the attic. Make sure everything is well insulated.

beenthere 08-09-2011 04:59 AM

If it just started this year. Check duct insulation first. If its ok. Then good chance the evap coil is dirty, and causing air stratification in the plenum.

minh.nguyen2 08-09-2011 10:15 AM

thanks everyone for your insight. I'm putting pieces of info together. How do I go about to clean a dirty evap coil ?

minh.nguyen2 08-09-2011 10:29 AM

can i do this myself or need to call a technician?
the unit is 20 years old. IS there a possibility for a new replacement? which will be costly

minh.nguyen2 08-09-2011 10:33 AM

Important thing to add:

the cool branch is gradually becoming warmer. I suspect its a matter of time before both branch stop giving cool air. Another word, the pproblem is spreading to the entire system.

JJboy 08-09-2011 10:35 AM

If you have access to the bottom of the a-coil you can do it. The best way to clean is removing the a-coil.

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