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troyhouse · Jun 27, 2009, 04:39 PM

Hi,

My central air conditioning unit in a single family home is not working. When I switch on Cool in thermostat, outside fan does not work, but I still get very little cool air from the vents.

Is there a way to switch on the outside fan?/

wmproop · Jun 27, 2009, 06:19 PM

Make sure the breakers to outside unit are on
Is there no sounds coming from outside unit?
You might need to walk outside and listen while someone from the inside turn the thermostat to cool position, make sure the fan switch is set to auto

troyhouse · Jun 27, 2009, 06:51 PM

Thks for the quick reply. Following is the info you requested:

1. no sound from the outside unit
2. don't know how to check the breakers, I checked in the main unit there was none in off position
3. there is no sound from the outside unit, fan does not operate
4. when the thermostat is in auto position, I do get mild air from the vents... but it does not cool the house...

Please provide your feedback on what else should I check ?

Thanks in advance.

wmproop · Jun 27, 2009, 07:17 PM

1st go to the outside unit,where the electric wiring goes into the unit,there is a very small thermostat type wire that goes into the unit. Inspect closly,(very close) looking for breaks or chewed wiring(possible dog or some other animal) follow the wire all the way to your furnace/airhandler
It sounds like you don`t have low voltage(24 volts) going to the a/c to make contactor click in
Let us know

Do you have and/or know how to use a multitester? To check for voltage

letmetellu · Jun 27, 2009, 07:18 PM

First you should have an electrical disconnect box there by the condensing unit, this would enable you to turn off the power to the unit. It also might contain fuses and it is possible that one of these fuses are bad.

Unless you want to change both fuses you would need an ohm meter to test each fuse to find out which one might be bad.

It is very dangerous to be inside of that box if you do not know what you are doing, you could easily come into contact with high voltage.

But if you do decide to do it yourself buy fuses of the same amperage and the same type, there are some fuses that are quite a bit cheaper than others so buy the more expensive ones. The others will blow as sone as you install them because they are not the right type.

When you buy the fuses also buy a fuse puller to protect yourself from getting shocked.

This may not be your problem but it is the first thing to check when trying to diagnose a problem.

Be very careful.

troyhouse · Jun 27, 2009, 07:33 PM

Other thing to add is that comed recently added the comverge unit that changes the cycle during peak hours and gives credit in the monthly bill... maybe the problem is related to that?

It looks like I will have to call someone for the service? Thanks for all the responses, it was great help.

letmetellu · Jun 28, 2009, 01:12 PM

Originally Posted by troyhouse

other thing to add is that comed recently added the comverge unit that changes the cycle during peak hours and gives credit in the monthly bill... maybe the problem is related to that?

it looks like i will have to call someone for the service? thanks for all the responses, it was great help.

If you would please explain the new coverage you added.

troyhouse · Jun 28, 2009, 01:15 PM

Originally Posted by letmetellu

If you would please explain the new coverage you added.

It's a unit by comed that basically controls the AC during peak hours. It shuts down for 10minutes or when the demand increases on hot days.

This was installed by comed (utility company) and I suspect it might have to do something with the issue, or something completely different like fuses... I am going to schedule an appointment tomorrow and will update everyone out here.