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Douglas
Douglas, HVAC Technician
Category: HVAC
Satisfied Customers: 3089
Experience:  Manufacture Rep for Major Brand, Technical Trainer, NATE
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I have a Lennox air handler model CB26UH. It is running but

Resolved Question:

I have a Lennox air handler model CB26UH. It is running but no cool air. Their is a small puddle of water at the base of the unit. The breakers are fine, and the unit is on, but not cooling. The unit is approx 2.5 years old. Thoughts or recommendations?
Submitted: 6 years ago.
Category: HVAC
Expert:  Douglas replied 6 years ago.
Chat Conversation Started
Douglas :

can you feel any air?

Douglas :

is the outdoor unit running?

Douglas :

Hi, can you see if the outdoor fan is running?

Douglas :

Hello?

Customer:

I'll have to check outside. Not running. My neighbor's unit is. so I saw what "working" looks like and mine is not working. I get air when I select "on" verus "fan". But not cold air.

Douglas :

ok so the indoor unit is running but not the outdoor?

Douglas :

I assume the thermostat is set to cool and the temp is turned down below the room temperature?

Douglas :

when you switch the fan switch to auto, does the indoor blower run?

Customer:

Yes, but only when I select "on/fan". I've been pushing 69 degrees, but it is 80 degrees.

Douglas :

can you tell me what thermostat you have?

Customer:

Does not blow on auto fan. Set to cool and 69 degrees, but reads 80.

Customer:

Let me check.. "lLuxpro"

Customer:

oops, "Luxpro"

Douglas :

ok.... the fan swtich inside the thermostat has 2 positions.....auto and on. when in the on position it is independent of the cooling. when in the auto postion, it is dependent on the 24 volt signal that makes the coolng come on..... so it sounds like when the thermostat is in cooling mode, the internal relay is not clicking in....

Douglas :

now, there can be several reasons....

Douglas :

the most likely scenerio is a bad thermostat

Douglas :

I say this because its' the only common relay that wouldnt allow both not to come on

Douglas :

one moment while I look for a pull off...

Customer:

how does one fix a "bad thermostat"?

Douglas :

are there mechanical switches ot buttons on the thermostat?

Douglas :

in other words, is the heat/cool switch a switch or buttons?

Customer:

No, only a side switch that you push for warm, cool or off. Same with the auto fan, on, or off. There is what looks like a mother board when I removed the thermometer face plate.

Customer:

A switch.

Douglas :

ok have you switched it off and back on?

Customer:

yes, a number of times.

Douglas :

ok.... do you have a helper handy?

Customer:

an assistant? no.

Douglas :

ok....how about a paperclip?

Customer:

i could find one. sounds MacGyver-ish.

Douglas :

yep, but we wont need any gum or shoelaces

Customer:

ok, hit me...

Douglas :

ok take the thermostat off the back plate

Customer:

ok,

Douglas :

now are the switches on the thermostat or on the base?

Customer:

thermostat.

Douglas :

good... you see a yellow wire connected to the y terminal?

Customer:

where is the "y" terminal. Is it labled?

Douglas :

on the backplate... noit on the thermostat

Douglas :

not that is

Customer:

Yes, I see it.

Douglas :

ok.... one sec.... my exit is coming up and I need to pull over to a parking lot

Customer:

Ok,

Customer:

please do not ask me to cross the yellow wire with the green wire when it should have been the blue wire and there is a big "BOOM".

Douglas :

no.... butsince you dont have a helper, we are going to do something different. Do you have a small screwdriver that would fit those screw terminals?

Customer:

Yup, have to find it. Be right back.

Douglas :

Give me a little credit.... I never lost a customer yet :)
Sealed

Douglas :

but you caught me off guard.... actually we do want to remove the yellow wire and put it in with the green wire.... Now, so you know, there is no voltage at either of these wires with the themrostat off. There is a relatively harmless 24 volts at the Red wire though so we want to stay away from there. If you are uneasy about this, you can turn the breaker to the air handler off and that will shut the control voltage off.

Douglas :

That is assuming the Yellow wire goes to the Y terminal and the Green goes to the G terminal.

Customer:

Ok, so talk me thru it step by baby step...

Douglas :

To answer your other question... how one fixes a thermostat?.... one doesnt, one replaces it. What we are doing here is validating the thermostat is indeed the problem because we dont want you spending money for unnessary parts. Additionally we will hopefully be able to get cooling on for the night

Customer:

Roger. Let's go.

Douglas :

ok.... so remove the yellow wire from it's Y terminal. We want to losten the G terminal and stick the Yellow wire under the terminal with the green wire;

Douglas :

who's Roger? (just kidding)

Customer:

ok, so i remove the yellow wire, and then match it up with the green wire and then put the screws back? Say a prayer..

Douglas :

Yes under the G terminal

Douglas :

ok...when you are done with that, you need to grab the thermostat and make sure the fan switch is in the auto postion. (not the on position) and reinstall the thermostat on the subbase..... If you turned the power off, you can turn it back on. Then we want to switch the fan switch to on. When you do this, the blower should come on as well as the outdoor unit and cold air should start coming out. Keep in mind some air conditioners have a time delay which may last up to 5 minutes.

Customer:

Ouchhhh, just joXXXXX, XXXXXe.

Douglas :

I wonder how many people who actually get electrocuted actually have time to spell out Ouchhhh?

Douglas :

If this works, I'll be amazed (not really, I am joking) but if it does, this tells me that either the mechanical cool switch contacts are corroded or otherwise have failed OR the internal time delay in the thermostat is stuck in prepetual dealy. Either way this will mean you will need to make a trip to your favorite home improvement store tomorrow to get a new one. Personally I would stay away from the Lux, Hunter or other off brands because in my experience they are not reliable in comparison to something like a honeywell, white rogers, or other trade brand thermostat

Douglas :

now, also if this works.... YOu can leave it cool for a while to get the home to a comfortable level by using the fan switch to turn it off and on with. You dont want to let the house get below 70 degrees or ugly things happen with the air conditioner that is a whole 'nuther discussion.

Douglas :

So what happend?

Douglas :

The system shows you stepped out of chat. I need to run for a few minutes to get checked in to my hotel for the night. I will check back in about 10 minutes or so.


 

Douglas :

If I have been helpful, please click accept. As always positive feedback and bonuses are welcome and greatly appreciated, as this is how I am compensated for my expertise, time and saving customers from costly service calls.

Expert:  Douglas replied 6 years ago.
Chat Conversation Ended

Your expert is gathering additional information and will be back with you shortly.
Expert:  Douglas replied 6 years ago.
If I have been helpful, please click accept. As always positive feedback and bonuses are welcome and greatly appreciated, as this is how I am compensated for my expertise, time and saving customers from costly service calls.

Thanks
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