AC condensing unit problem

Posted by JackpipE on June 18, 2008, 5:03 pm

> Do you have power coming back from your thermostat when the unit is
> calling for air? I would check for voltage at the stat and from the
> stat first. If you have an electronic stat you could have blown the
> stat board. Do you have heat?

Yes I do have heat because I already replaced the transformer on the
furnace that I also have blown.
Yes, I do have voltage on the thermostat.
From the attic unit (fan) there is 24V going to the thermostat. 3
wires white, red and green connecting to RC, G and Y on the
thermostat. There are 24V on the thermostat.
2 wires 24V go to the condensing unit. I do have the 24V on the
condensing unit at the end of the wire, but I can't find the voltage
on the electronic board or any other wire on the condensing unit as I
described in the first message opening this discussion.
I appreciate all your help but most of what you say sounds Chinese to
me. Is there an easy way I can test what's wrong with my condensing
unit? Can someone say with high confidence that it's the electronic
board could have blown ?

Thanks,
Jack

Posted by Mikepier on June 18, 2008, 9:22 am

> JackpipE wrote:

> > While replacing thermostat I have shorted out control transformer on
> > my AC system. I have split system and I already replaced the 24V
> > transformer for the fan (the unit an the attic) and got it to work.
> > However, the condensing unit is still not working. Here is a picture
> > of the electric parts on the unit:
> >http://e-pixel.net/AC_condensing_unit.jpgI have power 220V coming
> > into the unit and I have 24V now coming to
> > the unit from the attic fan. I was trying to follow the 24V on the
> > condensing unit but it goes inside the coil to the bottom (labeled on
> > the picture) and I can't find 24V anywhere on the unit. I checked
> > every other wire with the brown 24V wire and I don't have 24V
> > anywhere.
> > Can someone help me out here. What's inside the unit where the blue
> > 24V goes to? What else could be damaged here?
> > Thanks in advanced for all your help,
> > Jack

> You have a CARRIER 38ED high eff. from the 80's. =A0The electronic board =

is a

> "anti short - cycle" timer. =A0Remove it from the circuit. =A0 Your unit =

will

> light if you have 24 v from the two wires coming in. =A0You'll have to
> 'by-pass' the c.b. =A0Good luck.
> --
> Zyp- Hide quoted text -
> - Show quoted text -

My thermostat has a built in "anti cycle" feature, in that it will not
allow less than 5 minutes between compressor cycles. I don't know if
that board does the same thing, but just figured I let you know in
case the board is bad, you can use the T-stat as a substitute.

Posted by Moe Jones on June 18, 2008, 12:20 pm

Mikepier wrote:

>> JackpipE wrote:

>>> While replacing thermostat I have shorted out control transformer on
>>> my AC system. I have split system and I already replaced the 24V
>>> transformer for the fan (the unit an the attic) and got it to work.
>>> However, the condensing unit is still not working. Here is a picture
>>> of the electric parts on the unit:
>>> http://e-pixel.net/AC_condensing_unit.jpgI have power 220V coming
>>> into the unit and I have 24V now coming to
>>> the unit from the attic fan. I was trying to follow the 24V on the
>>> condensing unit but it goes inside the coil to the bottom (labeled
>>> on the picture) and I can't find 24V anywhere on the unit. I checked
>>> every other wire with the brown 24V wire and I don't have 24V
>>> anywhere.
>>> Can someone help me out here. What's inside the unit where the blue
>>> 24V goes to? What else could be damaged here?
>>> Thanks in advanced for all your help,
>>> Jack

>> You have a CARRIER 38ED high eff. from the 80's. The electronic
>> board is a "anti short - cycle" timer. Remove it from the circuit.
>> Your unit will light if you have 24 v from the two wires coming in.
>> You'll have to 'by-pass' the c.b. Good luck.
>> --
>> Zyp- Hide quoted text -
>> - Show quoted text -

> My thermostat has a built in "anti cycle" feature, in that it will not
> allow less than 5 minutes between compressor cycles. I don't know if
> that board does the same thing, but just figured I let you know in
> case the board is bad, you can use the T-stat as a substitute.

SOLID-STATE TIME GUARD II CIRCUIT,

protects unit compressor by preventing short

cycling. Time Guard II circuit provides a 5 ± 2minute

delay before restarting compressor after

shutdown for any reason. On normal start-up, the 5minute

delay occurs before thermostat closes. After

thermostat closes, the Time Guard II circuit then

provides a 3-second delay to prevent contactor

chattering.

--
Moe Jones
http://www.MoeJones.info

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AC condensing unit problem - Page 2