My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

On 05/03/2015 05:07 PM, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks




If it's fairly new , it may still be under warranty

philo wrote:
On 05/03/2015 05:07 PM, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks




If it's fairly new , it may still be under warranty
See if main contactor is energizing and check it's contacts
to see if they are badly pitted. Beyond that OP knows how to
charge the refrigerant?

philo wrote:
On 05/03/2015 05:07 PM, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks




If it's fairly new , it may still be under warranty

Is the compressor going? If not starting cap good?
Contactor contacts in good shape? Or need more refrigerant
after checking leak.

Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

The first thing you check is to be sure there's 220v to the relay . Then
that the relay closes when you call for cooling - and that 220 is getting
out of the motor side of the contactor . Next is the start cap , if the top
is bulged it's for sure dead . If not , I'm sure you have a meter that
measures capacitance . You might want to disconnect the fan power
temporarily to see if the compressor hums when first energized then quits
trying . No hum probably means it's dead or not getting power for some
reason , hum then click and stop indicates a high probability it's the cap .
If the compressor runs but no cooling , check the lines where you can see
them for an oil stain , which indicates a leak at that spot .
Do be sure to shut off power to the unit while you've got your fingers in
there unless you're actually checking voltage or performing tests . But you
knew that .
--
Snag

On 5/3/2015 6:07 PM, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks


A few possibilities. Low refrigerant, bad capacitor, bad relay. Do
you have the ability to check that stuff? If not, time to call a pro.
Best to call now instead of July when it is 105 degrees.

On 5/3/2015 6:28 PM, philo wrote:
On 05/03/2015 05:07 PM, Ignoramus18130 wrote:
* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.


If it's fairly new , it may still be under warranty

Warranty, check first.

Motor run cap is second thing to check.
Then, overload and windings.

-
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

On 5/3/2015 6:54 PM, Tony Hwang wrote:
On 05/03/2015 05:07 PM, Ignoramus18130 wrote:
* The outside unit fan is running, but the compressor itself
seems to be not running.

Is the compressor going?

Reading comprehension not firstly set turn
reversely backward?

-
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

On 2015-05-03, Ed Pawlowski wrote:
On 5/3/2015 6:07 PM, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks


A few possibilities. Low refrigerant, bad capacitor, bad relay. Do
you have the ability to check that stuff? If not, time to call a pro.
Best to call now instead of July when it is 105 degrees.

Guys, thanks a lot for your help.

I have a business buying and selling industrial parts and doing some
industrial scrap metal. So I think that I can troubleshoot this. I do
not have any experience working with refrigerant.

My understanding is, the compressor has a single phase motor with
external capacitor and resettable overload relay, right?

So, I would check, first, if there is 220v coming in (there likely is
since the fan runs), secondly whether there is 24v coming into the
coil of the contactor. If yes, I would check the overload relay. Maybe
after this, turn off the system for 30 minutes and turn it back on to
see if there is any humming or running compressor motor.

Then I should have a good idea if the problem is in the boards, power
coming in, relays, or capacitor, right?

i

On Sunday, May 3, 2015 at 5:07:05 PM UTC-5, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

The first thing to check is the static refrigerant pressure. Depending on the type refrigerant your AC has, the static pressure at 78 degrees F will be around 140 psi for R-22 and 230 psi for R-410a. The pressure can be higher if there is a crankcase heater. If you don't have refrigeration gauges, look for a low pressure cut out switch braised into the larger diameter(low side) line going into the compressor. There will be a pair of wires coming off of it going into the control panel and on the simplest condensing units it's connected in series with the contactor and "Y" terminal (yellow wire) on the terminal strip where the thermostat connects. The purpose of the low pressure cut out is to protect the compressor in case the refrigerant leaks out or the pressure gets low enough to cause the evaporator to freeze up.. Of course, with the power off, check the continuity of the switch and if it's open, it indicates a low pressure in the system or a defective switch. There is usually a wiring diagram on the inside or outside of the cover on the control panel/box. It would help to know the brand name and model of your AC or heat pump condenser so I could look it up. The reason I would check the pressure on a system with a pressure switch is because if it failed to run the first time you turned it on this season is that the refrigerant could have leaked out during the colder months. 8-]

[8~{} Uncle AC Monster

wrote :
On Sun, 03 May 2015 17:07:02 -0500, Ignoramus18130
wrote:

My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks


Leave the system off a while so the thermal has time to reset if it
tripped. Turn it on while someone is out by the condenser and listen
for a loud hum that stops in 15-20 seconds.. If you are getting that,
then try the start cap.
Bear in mind these things usually have a time delay on the compressor
and if the power was off, it may not start right away although the fan
will be running. Give it 5 minutes or so before you give up.

The transistorised timer in my ancient Carrier A/C was intermittant. It
would sometimes not turn on and sometimes turn off for no reason
If it turned off then later came on again another 3 minutes elapsed
befor the compressor came on.
Having a long expierince in electronic problem solveing I had 2 A/C
techs look at it before I decided to observe very carefully myself.
Some judicious banging on the case and watching revealed the above.
New timer works like a dream. :-)

--
John G Sydney.

On Sunday, May 3, 2015 at 9:24:26 PM UTC-5, Uncle Monster wrote:
On Sunday, May 3, 2015 at 5:07:05 PM UTC-5, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

The first thing to check is the static refrigerant pressure. Depending on the type refrigerant your AC has, the static pressure at 78 degrees F will be around 140 psi for R-22 and 230 psi for R-410a. The pressure can be higher if there is a crankcase heater. If you don't have refrigeration gauges, look for a low pressure cut out switch braised into the larger diameter(low side) line going into the compressor. There will be a pair of wires coming off of it going into the control panel and on the simplest condensing units it's connected in series with the contactor and "Y" terminal (yellow wire) on the terminal strip where the thermostat connects. The purpose of the low pressure cut out is to protect the compressor in case the refrigerant leaks out or the pressure gets low enough to cause the evaporator to freeze up. Of course, with the power off, check the continuity of the switch and if it's open, it indicates a low pressure in the system or a defective switch. There is usually a wiring diagram on the inside or outside of the cover on the control panel/box. It would help to know the brand name and model of your AC or heat pump condenser so I could look it up. The reason I would check the pressure on a system with a pressure switch is because if it failed to run the first time you turned it on this season is that the refrigerant could have leaked out during the colder months. 8-]

[8~{} Uncle AC Monster

Oh crap! bangs head against the wall I went back and read the original post to see that the fan was running. A different troubleshooting scheme is required. Since the fan and compressor on an AC only condensing unit usually use the same contactor, the compressor could be dead because the internal thermal overload protector has opened breaking the connection to the windings. If the refrigerant leaked out of the system, the compressor overheats quickly when powered up and the overload shuts it down until the compressor cools down and the cycle starts over. It can take a long time for the compressor to cool down. You can check for this by removing a side panel and reaching in and placing your hand on the compressor. If it's hot or very hot to the touch, that could indicate an overheated compressor due to refrigerant loss. Low or no refrigerant in the system can be verified with a set of gauges. You can look for other problems like a defective start or run capacitor. If you could take pictures and post them to a photo sharing site of the outside of the unit showing the brand name and possibly model number. Then some shots of the inside with the cover off of the control box and a view of the compressor, I could give you a better idea of what to look for. There are several other things that can keep the compressor from running but you need to make some continuity tests of the compressor windings and visual inspection of all the connections to the compressor and inspect the run capacitor to see if the top of the metal can, where the terminals are located, has bulged out. If you good at troubleshooting electrical circuits, look for the diagram which can be on the inside of the cover on the side of the condensing unit or the cover of the control box. You should post a picture of that too. It would be easier for me to point out what to look for if I could see some pictures. 8-]

[8~{} Uncle AC Monster

On 5/3/2015 10:01 PM, Ignoramus18130 wrote:

Guys, thanks a lot for your help.

I have a business buying and selling industrial parts and doing some
industrial scrap metal. So I think that I can troubleshoot this.

CY: What does buying scrap have to do with
troubleshooting an AC system?

I do
not have any experience working with refrigerant.


CY: Bummer.

My understanding is, the compressor has a single phase motor with
external capacitor and resettable overload relay, right?

CY: Not the ones I've worked with.


So, I would check, first, if there is 220v coming in (there likely is
since the fan runs),

CY: Yes,likely.

secondly whether there is 24v coming into the
coil of the contactor.

CY: Using some deductive logic, you can tell
if there is 24 VAC without a meter. Just from
your posts.

If yes, I would check the overload relay. Maybe
after this, turn off the system for 30 minutes and turn it back on to
see if there is any humming or running compressor motor.

CY: Not what I'd have done.


Then I should have a good idea if the problem is in the boards, power
coming in, relays, or capacitor, right?

CY: From what you write, you'd have some data,
but not much idea.


i

On Sunday, May 3, 2015 at 10:01:47 PM UTC-4, Ignoramus18130 wrote:
On 2015-05-03, Ed Pawlowski wrote:
On 5/3/2015 6:07 PM, Ignoramus18130 wrote:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks


A few possibilities. Low refrigerant, bad capacitor, bad relay. Do
you have the ability to check that stuff? If not, time to call a pro.
Best to call now instead of July when it is 105 degrees.

Guys, thanks a lot for your help.

I have a business buying and selling industrial parts and doing some
industrial scrap metal. So I think that I can troubleshoot this. I do
not have any experience working with refrigerant.

My understanding is, the compressor has a single phase motor with
external capacitor and resettable overload relay, right?

So, I would check, first, if there is 220v coming in (there likely is
since the fan runs), secondly whether there is 24v coming into the
coil of the contactor.

If there wasn't 24V going to the contactor, the fan wouldn't be
running. That would seem to suggest that the contactor/relay is
OK too and supplying 240V to the output side which goes to the
fan and compressor.

Ignoramus18130 posted for all of us...



My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

Yes, call the installing/servicing co and get them out now before the
temperature rises. It may still be under warranty...

--
Tekkie *Please post a follow-up*

On Mon, 4 May 2015 19:29:51 -0400, Tekkie® wrote:

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

Yes, call the installing/servicing co and get them out now before the
temperature rises. It may still be under warranty...

I have my HVAC unit serviced, inspected - twice a year. It can get
117°F out here

Pool Fight!

In ,
Ignoramus18130 typed:
My home A/C was turned on yesterday, and we realized that it blows
warm air instead of cold. I did a little bit of investigation and also
changed the filter.

* The outside unit fan is running, but the compressor itself
seems to be not running. I measured amps going to it, it is about
1.4 amps 220v, consistent with only the fan running.

* The cold refrigerant line (with thermal insulation) is not actually
cold but warm.

* I just changed a filter. The evaporator coil was not easy to see so
I did not look at it.

Would you have any troubleshooting suggestions. The outside unit is
relatively new. Thanks

Two things:

1) Where are you located? The reason that I ask is that I am located in an
area where my gas and electric utility provider has a deal where they will
come out and look at a broken item such as HVAC, figure out what is wrong,
and give a price to fix it. If I don't use them to fix it, there is no
charge for the visit. So, it's a free diagnosis. If you are lucky enough
to have a utility company that provides that free service, let them check it
out for you. I sometimes pay them to do the work if it is something basic
and not too expensive. Their repair prices are high in general, but
sometimes they can just fix what's wrong while they are there and I'm done
with it.

2) Since the condenser fan is running, this may not be applicable, but two
times recently when my AC was just blowing hot air it was because the lawn
company accidentally weed-whacked the 24-volt wire running to the condenser
(two different properties).

OK, guys, thanks to those who encouraged me to look further.

Again, what was happening before was that the fan was running, but the
compressor was not running.

I turned off the thermostat altogether, for several days, due to cool
weather. Today, the weather was warm enough to try looking into my AC
again.

I turned the thermostat to COOL and nothing at all is happening. The
furnace fan is not blowing and the outside compressor and fan are not
running at all.

This is a change from 4 days ago, when at least something was running,
now nothing is running.

I spent some time today investigating this. This is what I found:

*) There is 120 volts coming into the furnace from the circuit breaker

*) There is 120 volts on the input of the 24 VAC transformer

*) There is no 24 VAC on the output of the transformer, the output is
0 volts AC.

*) The secondary (low voltage) winding has resistance appx. 1 ohm

*) The primary (high voltage) winding has infinite resistance, in
other words it is broken.

So, on its face the answer is that my air conditioner is not working
because the control transformer is not functioning. It should be easy
to replace.

What I am not sure is why it failed. Did it happen simply due to age,
or there was perhaps overdraw of current or a short in the 24v system
that caused it to fail? Any thoughts on this?

I can easily find a 120-24v transformer, but I am not sure if I found
the root cause or not.

i

On Thursday, May 7, 2015 at 8:03:14 PM UTC-5, Ignoramus18857 wrote:
OK, guys, thanks to those who encouraged me to look further.

Again, what was happening before was that the fan was running, but the
compressor was not running.

I turned off the thermostat altogether, for several days, due to cool
weather. Today, the weather was warm enough to try looking into my AC
again.

I turned the thermostat to COOL and nothing at all is happening. The
furnace fan is not blowing and the outside compressor and fan are not
running at all.

This is a change from 4 days ago, when at least something was running,
now nothing is running.

I spent some time today investigating this. This is what I found:

*) There is 120 volts coming into the furnace from the circuit breaker

*) There is 120 volts on the input of the 24 VAC transformer

*) There is no 24 VAC on the output of the transformer, the output is
0 volts AC.

*) The secondary (low voltage) winding has resistance appx. 1 ohm

*) The primary (high voltage) winding has infinite resistance, in
other words it is broken.

So, on its face the answer is that my air conditioner is not working
because the control transformer is not functioning. It should be easy
to replace.

What I am not sure is why it failed. Did it happen simply due to age,
or there was perhaps overdraw of current or a short in the 24v system
that caused it to fail? Any thoughts on this?

I can easily find a 120-24v transformer, but I am not sure if I found
the root cause or not.

i

Check the thermostat wire out at the condensing unit which could have been damaged during grass cutting. Check the resistance across the pair of the T-stat cable from the furnace to the outdoor unit then with the wire disconnected at the outdoor unit. Sometimes power surges can cause a control transformer to fail. If you get another transformer, get a 2 amp fuse and pigtail fuse holder and put it in series with the secondary and your meter to check current draw of the thermostat circuits. Use common sense. 8-)

[8~{} Uncle Control Monster

On 2015-05-08, Ignoramus18857 wrote:
OK, guys, thanks to those who encouraged me to look further.

Again, what was happening before was that the fan was running, but the
compressor was not running.

I turned off the thermostat altogether, for several days, due to cool
weather. Today, the weather was warm enough to try looking into my AC
again.

I turned the thermostat to COOL and nothing at all is happening. The
furnace fan is not blowing and the outside compressor and fan are not
running at all.

This is a change from 4 days ago, when at least something was running,
now nothing is running.

I spent some time today investigating this. This is what I found:

*) There is 120 volts coming into the furnace from the circuit breaker

*) There is 120 volts on the input of the 24 VAC transformer

*) There is no 24 VAC on the output of the transformer, the output is
0 volts AC.

*) The secondary (low voltage) winding has resistance appx. 1 ohm

*) The primary (high voltage) winding has infinite resistance, in
other words it is broken.

So, on its face the answer is that my air conditioner is not working
because the control transformer is not functioning. It should be easy
to replace.

What I am not sure is why it failed. Did it happen simply due to age,
or there was perhaps overdraw of current or a short in the 24v system
that caused it to fail? Any thoughts on this?

I can easily find a 120-24v transformer, but I am not sure if I found
the root cause or not.

OK, I think that I understand what happened, the root cause.

The cause was that the contactor for the outside compressor was not
closing properly. That is why the compressor was not running
originally.

Because the contactor would not close, the contactor coil used
excessive current. After a while of this, the control transformer
burned out.

I actually figured this out just by sitting and thinking.

Then I went outside, opened the control area of the compressor unit,
and found the following confirming evidence:

1) The compressor motor works just fine when I push the contactor to
close, by hand

2) The contactor coil stinks and looks blackened/browned, instead of
wholesome gold like color.

3) The coil also stinks, like burned out coils are wont to do.

So, I think, that I am looking at replacing both the contactor unit,
as well as the transformer.

I

Ignoramus18857 wrote:
OK, guys, thanks to those who encouraged me to look further.

Again, what was happening before was that the fan was running, but the
compressor was not running.

I turned off the thermostat altogether, for several days, due to cool
weather. Today, the weather was warm enough to try looking into my AC
again.

I turned the thermostat to COOL and nothing at all is happening. The
furnace fan is not blowing and the outside compressor and fan are not
running at all.

This is a change from 4 days ago, when at least something was running,
now nothing is running.

I spent some time today investigating this. This is what I found:

*) There is 120 volts coming into the furnace from the circuit breaker

*) There is 120 volts on the input of the 24 VAC transformer

*) There is no 24 VAC on the output of the transformer, the output is
0 volts AC.

*) The secondary (low voltage) winding has resistance appx. 1 ohm

*) The primary (high voltage) winding has infinite resistance, in
other words it is broken.

So, on its face the answer is that my air conditioner is not working
because the control transformer is not functioning. It should be easy
to replace.

What I am not sure is why it failed. Did it happen simply due to age,
or there was perhaps overdraw of current or a short in the 24v system
that caused it to fail? Any thoughts on this?

I can easily find a 120-24v transformer, but I am not sure if I found
the root cause or not.

i

I'd check the contctor in the ODU. Check the coil.

On 2015-05-08, Tony Hwang wrote:
Ignoramus18857 wrote:
OK, guys, thanks to those who encouraged me to look further.

Again, what was happening before was that the fan was running, but the
compressor was not running.

I turned off the thermostat altogether, for several days, due to cool
weather. Today, the weather was warm enough to try looking into my AC
again.

I turned the thermostat to COOL and nothing at all is happening. The
furnace fan is not blowing and the outside compressor and fan are not
running at all.

This is a change from 4 days ago, when at least something was running,
now nothing is running.

I spent some time today investigating this. This is what I found:

*) There is 120 volts coming into the furnace from the circuit breaker

*) There is 120 volts on the input of the 24 VAC transformer

*) There is no 24 VAC on the output of the transformer, the output is
0 volts AC.

*) The secondary (low voltage) winding has resistance appx. 1 ohm

*) The primary (high voltage) winding has infinite resistance, in
other words it is broken.

So, on its face the answer is that my air conditioner is not working
because the control transformer is not functioning. It should be easy
to replace.

What I am not sure is why it failed. Did it happen simply due to age,
or there was perhaps overdraw of current or a short in the 24v system
that caused it to fail? Any thoughts on this?

I can easily find a 120-24v transformer, but I am not sure if I found
the root cause or not.

i

I'd check the contctor in the ODU. Check the coil.

Tony, it was exactly as you said, as I find out. Looks like I need to
replace both the contactor and now the transformer.

i