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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have one zone that is not cooling and the purge light is

Customer Question

I have one zone that is not cooling and the purge light is flashing on my honeywell EMM-3u
Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.

hello,

my name is Billy.

Have you checked the damper to make sure it has opened fully?

Customer: replied 1 year ago.
Hi Billy are you still there
Expert:  BillyHvac replied 1 year ago.

Yes I am....a stuck damper can cause this and I wondered if you checked the physical damper in the duct yet

Customer: replied 1 year ago.
let me go check - I haven't checked that yet
Expert:  BillyHvac replied 1 year ago.

standing by...the damper must open fully which in turn trips an end switch telling the panel it is open.

Customer: replied 1 year ago.
There are to small boxes on top of two different ducts but dampers must be inside the duct
Customer: replied 1 year ago.
There is also a manual damp[er
Expert:  BillyHvac replied 1 year ago.

the damper blades are in the duct, but the motor is in the small box

Customer: replied 1 year ago.
I took the cover off the box. How do I know if it is stuck
Expert:  BillyHvac replied 1 year ago.

is there a line on the motor shaft?

Or can you take a pic and post here using the attach files link?

Customer: replied 1 year ago.
I cannot see the motor shaft it is under the motor
Expert:  BillyHvac replied 1 year ago.

ok do you have the motorized close or spring return?....or what is the damper number

Customer: replied 1 year ago.
I look likE IT HAS A SPRING under the motor
Customer: replied 1 year ago.
How do I know what the damper number is?
Expert:  BillyHvac replied 1 year ago.

turn that zone off and watch if it returns closed.

The damper number is ***** an ARD

Customer: replied 1 year ago.
I had my wife turn the thermostat up and the motor started rotating
Customer: replied 1 year ago.
Zone 1 light turned of on the mini
Customer: replied 1 year ago.
purge light still flashing
Expert:  BillyHvac replied 1 year ago.

thank you, ***** ***** pressed purge override yet?

Customer: replied 1 year ago.
earlier let me try again
Customer: replied 1 year ago.
I did and all three zone lights came on
Customer: replied 1 year ago.
but yellow purge light still flashing
Expert:  BillyHvac replied 1 year ago.

thank you.

on right side of board...DATS terminals...are there wires on those 2 terminals?

Customer: replied 1 year ago.
no
Expert:  BillyHvac replied 1 year ago.

This is indicative if a issue in the zone board.

If a sensor were present that would be our first choice but your system has no dats.

Do you have all 3 zones filled

Customer: replied 1 year ago.
I did but I turned the air back on
Customer: replied 1 year ago.
What do you want me to do now
Expert:  BillyHvac replied 1 year ago.

How many zones do you have? (thermostats)

Customer: replied 1 year ago.
3
Expert:  BillyHvac replied 1 year ago.

and the other 2 work fine?

Customer: replied 1 year ago.
well i know the main living room is. Do you want me to test the other room?
Expert:  BillyHvac replied 1 year ago.

yes please

Customer: replied 1 year ago.
I did and the damper opened up for that room
Expert:  BillyHvac replied 1 year ago.

Thank you.

Now when all 3 are asked to be open....do all 3 appear to open?

Customer: replied 1 year ago.
not zone 3
Customer: replied 1 year ago.
strange I only see 2 motor controlled thermostats
Customer: replied 1 year ago.
should I check to see if the intake is sucking?
Expert:  BillyHvac replied 1 year ago.

Can you identify what room has what damper?.....and also follow the wires from the zone panel to each damper

Expert:  BillyHvac replied 1 year ago.

I assume now that 2 zones are open ac is on?

Customer: replied 1 year ago.
I hear the fan running
Expert:  BillyHvac replied 1 year ago.

ok we need to find the 3rd damper

Customer: replied 1 year ago.
ok let me try
Customer: replied 1 year ago.
i don't think there is a third damper. I have two ac units and I thing the living room has a unit all to itself
Expert:  BillyHvac replied 1 year ago.

so on the zone panel..bottom row....you have only 2 zones wired?

Customer: replied 1 year ago.
I think the second unit is just for the mast bedroom and upstairs room
Customer: replied 1 year ago.
Thatt is correct
Expert:  BillyHvac replied 1 year ago.

let me gather my thoughts again....

so the master bed unit is working...(separate unit)

living room zone is working fine....

but a second zone on the panel is not?

but you watched the damper open?

Customer: replied 1 year ago.
master bedrooom is not working
Expert:  BillyHvac replied 1 year ago.

But the master bedroom is not driven off the zone panel?

That one is stand alone?

Customer: replied 1 year ago.
living room is fine
now that i think of it the upstairs bedroom may not be working well either
Customer: replied 1 year ago.
living room on its own ac unit
Customer: replied 1 year ago.
billy why did you do that