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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 an lennox Hvac unit which just stop getting power.

Customer Question

I have an lennox Hvac unit which just stop getting power. the red & green light are both off. i changed tge capacitor & still. i do have power coming into the unit, measured at the contact.
Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.

hello,

some Lennox units have a small black rocker switch on the metal panel to the right of the circuit board. Have you checked this small rocker switch to reset?

Customer: replied 1 year ago.
do you have a pic? I do have a pull out cut off power plug on the side of the house connected to the unit
Expert:  BillyHvac replied 1 year ago.

what is your model number?

Customer: replied 1 year ago.
i have attached pic
Expert:  BillyHvac replied 1 year ago.

that is an ac coil on the furnace. Can you remove both doors of furnace...take pic...and post?

Customer: replied 1 year ago.
not right now dont wanna disturb the neighborss...
Customer: replied 1 year ago.
I changed the capacitor & still
Expert:  BillyHvac replied 1 year ago.

ok I understand now...

The power to the unit...have you checked it with a meter? Is it 230 volt?

Customer: replied 1 year ago.
this is a pic of board
Expert:  BillyHvac replied 1 year ago.

if you press the center bar of contactor in does unit do anything?

Customer: replied 1 year ago.
lol Im still a novice.. touch it with what?
Expert:  BillyHvac replied 1 year ago.

a pencil, screwdriver stick....we want to just press the spring loaded center of the contactor down

Customer: replied 1 year ago.
ok gimme a sec
Customer: replied 1 year ago.
the fan comes on
Expert:  BillyHvac replied 1 year ago.

thank you...so we are missing the signal from inside...does the indoor blower turn on inside the house?

Customer: replied 1 year ago.
i will need to hold the center down and ask my wife it kicks in correct?
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  BillyHvac replied 1 year ago.

no....inside the house is a blower unit...if you set the thermostat to fan on...does the indoor blower run in the house?

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

that is where we need to start,,,it is the signal that starts at blower unit..goes to thermostat and then to outdoor unit. Do you know where your indoor blower is?

Customer: replied 1 year ago.
i hear clicking from the unit in the closet but no resposnse
Expert:  BillyHvac replied 1 year ago.

can you see if the breaker is on to the indoor unit? Also I see you have a zoned system so you have more than one thermostat?

Customer: replied 1 year ago.
i have two thermo but 1 unit so i set both to the same temp to avoid confusion. ihave one breaker on the outside panel & a pull plug on the side
Expert:  BillyHvac replied 1 year ago.

ok,

the issue is inside this unit.

This is 220v also...do you have a meter to test this unit?

Customer: replied 1 year ago.
i have this one
Expert:  BillyHvac replied 1 year ago.

ok...set volts~ 750....then we need to test main power to this appliance..hot wire to hot wire...not hot wire to ground

Customer: replied 1 year ago.
ok gimme a sec ima take panel off
Customer: replied 1 year ago.
am I measuring at the breaker? this is my inside
Expert:  BillyHvac replied 1 year ago.

put the meter leads on the 2 terminals where the 2 black wires are on right side.

Customer: replied 1 year ago.
ok i got 243
Expert:  BillyHvac replied 1 year ago.

now the left side where it leaves

Customer: replied 1 year ago.
same 243
Expert:  BillyHvac replied 1 year ago.

ok, to the left of what you just tested is a transformer..brass color cube.

This takes 243 in one side and supposed to have 24v the other side.

Can you test this?

Customer: replied 1 year ago.
where do i place the prongs? in the nut bolts? on the other side it has screws
Customer: replied 1 year ago.
white & orange?
Expert:  BillyHvac replied 1 year ago.

the opposite side...what are terminals? we will just test output..

Customer: replied 1 year ago.
the other side
Expert:  BillyHvac replied 1 year ago.

excellent...one meter lead on blue wire terminal and the other meter lead on the brown wire terminal.

Customer: replied 1 year ago.
i got a spark
Customer: replied 1 year ago.
n break trip
Expert:  BillyHvac replied 1 year ago.

just by putting meter leads on?

Customer: replied 1 year ago.
yeah now the breaker is out reading 0
Expert:  BillyHvac replied 1 year ago.

the side we are testing is only 24 v..the breaker is 240v.

reset the breaker...then carefully test the 2 terminals again...the only thing that could trip breaker is if a bare wire touched ground

Customer: replied 1 year ago.
i had to reset the breaker in garage
Customer: replied 1 year ago.
0k got 26
Expert:  BillyHvac replied 1 year ago.

good.

this means we have main power and we have control power. But the zone panel is not closing signal for the equipment.....you still game to go into the zone panel up at top marked Honeywell?

Customer: replied 1 year ago.
lets do it! lol
Expert:  BillyHvac replied 1 year ago.

remove cover...on left side towards bottom is a block with R and C.

we need to test those 2 terminals...meter lead on each

Customer: replied 1 year ago.
can i touch the gold squares ?
Customer: replied 1 year ago.
i got 24
Expert:  BillyHvac replied 1 year ago.

thank you

now above that is Equipment module..put meter red lead on RC/RH and the meter black lead down on the C tested previously

Customer: replied 1 year ago.
i got 1
Expert:  BillyHvac replied 1 year ago.

ok, we have narrowed this down alot and are ready for the final tests...do you have or can make a strip of wire 4-5" long with the ends stripped?

Customer: replied 1 year ago.
gimme a few ima go to thegarage
Customer: replied 1 year ago.
got one
Expert:  BillyHvac replied 1 year ago.

excellent....the Equipment block...one end of wire on Rc/Rh (either one) and the other end of wire touching G...tell me if blower kicks on

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

ok we have the 2 end points with issue in between...follow the wire from the Equipment block Rc/rh....where does it go or end?

Customer: replied 1 year ago.
the red wire ..it joins in the panel n split to two locations back to honeywell right side and a device on the bottom of the pan.. look at images
Expert:  BillyHvac replied 1 year ago.

that switch in pan is likely breech. wire from rc/rh runs to this switch..then from switch does it go to transformer? almost there...

Customer: replied 1 year ago.
it goes to another trans on the side of unit...
Customer: replied 1 year ago.
is this still good look at pic.. from the spark earlier
Expert:  BillyHvac replied 1 year ago.

ok, we have a bad wet switch...or a bad time delay relay (black box).

cut the wet switch wires and wire nut together or twist and tape.

then jump rc/rh to g again at equipment block.......This is last test

Customer: replied 1 year ago.
can i just removed them from the nuts and connect solo.. look at pic
Expert:  BillyHvac replied 1 year ago.

yes...basically we just want to pretend that switch was never there...

Customer: replied 1 year ago.
when i turn on the unit i got this
Expert:  BillyHvac replied 1 year ago.

that was it....go ahead and press next.

You have a bad wet switch...is anything starting to kick on yet?

Customer: replied 1 year ago.
not yet i did the wire jump n no response.( u think the transformer spark earlier may need to be replace as well)
Expert:  BillyHvac replied 1 year ago.

It would not hurt at all as you never know when compromised.

So we know:

Outdoor unit has power

Indoor unit has main power

Indoor unit transformer works with 24v

Zone board gets 24v from remote transformer

Everything is in place except for the wet switch is bad and you have a purge delay.

Now at thermostats..turn all off but turn fan switch to on.

Customer: replied 1 year ago.
i try it
Customer: replied 1 year ago.
nothing happens
Expert:  BillyHvac replied 1 year ago.

and rc to G on equipment block did not work either?

Customer: replied 1 year ago.
none worked so far
Expert:  BillyHvac replied 1 year ago.

I am very sorry but I have to go offline. Is it possible to continue tomorrow or would you like me to transfer to an online tech?

Customer: replied 1 year ago.
what time tomorrow?
Expert:  BillyHvac replied 1 year ago.

anytime you respond I will be notified. I am scheduled for 10-12 and 5-10

Customer: replied 1 year ago.
ok 10 am eastern?
Expert:  BillyHvac replied 1 year ago.

yes

Customer: replied 1 year ago.
ok i will respond at 10 am sharp! thansk!
Customer: replied 1 year ago.
Customer: replied 1 year ago.
you back?
Customer: replied 1 year ago.
hello
Expert:  BillyHvac replied 1 year ago.

I am sorry, whether it is sickness or deer hunting I was short techs today. I do not know quite yet when I can get back on so I will release the question so that anyone can assist.

Customer: replied 1 year ago.
can so one respond?