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zachv · Apr 26, 2009, 11:49 AM

Hi,
I have an outside compressor and a forced hot air furnace setup that's been working great for years... except today when I tried the A/C for the first time.

Today, when I flipped the thermostat over to cool, I heard the compressor kick on, but then I noticed that the blower inside the furnace never did. So, just to be sure that the blower was still functional I kicked on the heat, and the furnace fired up no problem and was blowing heat fine. At least I know the blower itself is working fine.

I tried the A/C a few more times, this time actually down at the furnace, so I could hear the sequence. And the compressor definitely kicks in immediately (I can hear it running), and I can hear the refrigerant coursing through the lines and the A-coil. But the blower seems to start for maybe 1 or 2 seconds, but then just kicks out. I also noticed the light on the control board turn on and then off out the same time that the blower does.

And the compressor seems perfectly willing to stay on, unless I turn it off at the thermostat.

Any ideas?

Thanks for any help,
--Zach

Joshdta · Apr 26, 2009, 12:12 PM

Sounds like your control board is going bad. Does the fan work in the fan on position?

zachv · Apr 26, 2009, 01:30 PM

Just tried, and nope it doesn't. Same symptom as before. The control board and blower turn on maybe a second or 2 and then shut off... leaving the compressor running outside.

Any addition tests I should do? Or is it time to pay someone to come and take a look?

Joshdta · Apr 26, 2009, 01:41 PM

What brand furnace do you have?

Joshdta · Apr 26, 2009, 01:42 PM

Do you know here your control board is?

Joshdta · Apr 26, 2009, 01:42 PM

You may be able to put the cooling wire on eac and see if it works sometimes this has a different relay.

zachv · Apr 26, 2009, 01:50 PM

One other though... Even though this furnace and blower work fine for heat, you're thinking that something is messed on the control board related to A/C only?

Are there any diagnostics I can do to rule in/out the control board for sure?

For the record, the furnace is a Coleman Evcon, model # G9D10014UPC11C.

Thanks,
--Zach

zachv · Apr 26, 2009, 01:54 PM

Wow, you're quick... by the time I got back downstairs and back again to write my last follow-up, you have already hit me with 3 questions:

1) Cooling wire to EAC... no problem moving the wire. Which color should I be looking for? Or which contact?

2) yep, I know where the control board is. The panel covering has a nice lockout switch that I keep forgetting about!

And I mentioned the model # in the last post. Is that the info you were looking for?

Joshdta · Apr 26, 2009, 01:54 PM

Well let me think, is this a new furnace? Like with in 5 yrs old?

Joshdta · Apr 26, 2009, 01:56 PM

On the control board, there should be a wire that says heat probably red, and a wire that is on the cool terminal probably black

Joshdta · Apr 26, 2009, 01:58 PM

Your unit will probably have a 4 speed fan motor

zachv · Apr 26, 2009, 02:05 PM

Yep... pretty new furnace. 5 years sounds about right.

OK, I see the black wire on the cool terminal. It's a spaded terminal, not a screw terminal, if that helps...

I also see the EAC terminal. Want me to move the black terminal from cool to EAC? Leave the each hanging for now?

For your info, on the upper terminal block where the white wires are, there is no white wire on the EAC terminal there.

Also, what exactly is EAC? Electronic air cleaner? Maybe?

zachv · Apr 26, 2009, 02:06 PM

Sorry little typo in the last email... should have read "leave EAC hanging for now?"

Joshdta · Apr 26, 2009, 02:10 PM

Is there a wire on the eac now? And yes it stands for electric air cleaner

zachv · Apr 26, 2009, 02:13 PM

There is a black wire on the EAC terminal now (near the cool terminal), just not a white wire on the other EAC terminal.

Joshdta · Apr 26, 2009, 02:14 PM

Can you trace it and see where it goes? Before we switch them I do not want you to mess anything up. Do you have a air cleaner?

zachv · Apr 26, 2009, 02:18 PM

I'll go try and trace it now, but no I don't have an air cleaner... I have A/C and a humidifier, but the only thing cleaning my air is the regular inline paper filter.

Joshdta · Apr 26, 2009, 02:23 PM

OK well if it does not go to anything then put the cool on the eac and leave the eac hang and try it

zachv · Apr 26, 2009, 02:23 PM

OK, traced the EAC wire and it just dead-ends, with nice crimped terminator on it... nothing on it.

Should I try it? Switch the cool with the EAC? And give it a whirl?

Joshdta · Apr 26, 2009, 02:24 PM

Yep