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Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2014
Experience:  14 years experience in the HVAC field of service, installation, Manual J & D calculations
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Aircon blower not working

This answer was rated:

My air conditioner fan is not working outside, but the inside fan is working. How can I remedy the problem?

Matthew:

Can you tell if the internal compressor of the outdoor unit is running and it is just that the fan on top isn't turning or is nothing running outside? If the compressor was running without the fan on top running the noise would be incredibly loud you couldn't miss it.

Customer:

Nothing is running outside.

Matthew:

You either have no high voltage to the outdoor unit, no low voltage to the outdoor unit, or the capacitor is bad inside the unit. If you take the panel off the outdoor unit where the wires run into it see if you can find the contacts and see if the plunger is pulled down. I'll send a picture of what I’m talking about.

Matthew:

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Matthew:

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Matthew:

This plunger in the middle will be up and the points not touching down when there is no 24v to them and pulled down with the points touching the metal below when there is 24v to them.

Matthew:

Tell me if they are down with the thermostat calling for cooling.

Matthew:

This next picture is the capacitor inside the outdoor unit. If the plunger is pulled down then you need to inspect this capacitor and see if it is swollen and bulged up. Make sure you are not touching any wires or parts you are just inspecting visually.

Matthew:

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Matthew:

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Matthew:

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Matthew:

This last picture shows you what a shorted capacitor looks like. The one on the left the top is bulged outward instead of concaved.

Matthew:

What did you find?

Customer:

The capacitor looks normal. The plunger part looks as if it’s in the middle.

Matthew:

Right, but you have to see if it is pulled in. If you can't tell then take a screw driver and push in on the middle black plastic piece. See if it is already down or it goes down.

Matthew:

Make sure you push on the BLACK PLASTIC part.

Customer:

The plunger is in the middle of the two flat black parts shown in figure 2?

Matthew:

Right, you have the 4 gold screws then between 2 of the screws (one top and one button) there is a small little copper piece with a black plastic plunger holding it.

Customer:

That piece is out!

Matthew:

This piece with the 2 points and the black holder is the (contacts). This little plunger goes down when 24v is applied and bridges the button voltage up through to the top part.

Matthew:

That means there is no 24v being sent.

Matthew:

You either have a broken wire from point A. the outdoor unit to point B. the thermostat. Or you have a safety\ device like a condensate pump that is tripped. Is your furnace in the basement or attic?

Customer:

When it is pushed in, it starts up.

Matthew:

Right!

Matthew:

That’s good that means there is high voltage so your problem is the outdoor unit isn't getting the signal to come on for whatever reason.

Customer:

The pump is on the main floor!

Matthew:

We can eliminate the thermostat as a possible cause by taking the wire going to Y on the thermostat and placing it under R with the wire already there. If the thermostat is malfunctioning then when you do this the outdoor unit would come right on.

Matthew:

Do you have a condensate pump that pushes the water out of the home or does it gravity drain via 3/4" PVC all the way out?

Customer:

A gravity drain!

Matthew:

Is there a metal drain pan under the furnace with a float switch on the pan that has wires tied in with the thermostat wires?

Matthew:

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Float switch!

Matthew:

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Customer:

All I see is a big motor sitting on the floor.

Customer:

I don't see the float switch.

Customer:

I couldn't push the plunger down outside. It wouldn't get down. It only starts up when it is touched

Matthew:

I would check the thermostat wire going into your outdoor unit. There is 2 colored wires that hook to the unit make sure one of them isn't loose or broken outside this wire gets stepped on and hit with the weed eater a lot and pulled loose.

Matthew:

When you manually push it down it starts up but as soon as you let go it goes off again. It will only stay down if there is 24v energizing it to.

Matthew:

Now it is possible that the contacts are bad they get warn and will not pull the plunger down. Most often though when this happens the contacts will sit there and chatter trying to pull down but don’t' stick.

Matthew:

You would need a volt meter to test and see if there is actually 24v at the contacts to know for sure whether it was a bad contact or if there just wasn't 24v present.

Customer:

I am not seeing any loose wires. The black plunger if pushed in works. As soon as we let go, it turns off.

Matthew:

You don't have 24v from somewhere. The two wires that come into the outdoor unit tie under wire nuts check these and make sure they are good.

Customer:

Wires look ok. Can I place a piece of plastic and tape it to hold it in, just for the night to cool off?

Customer:

Then I can call for service?

Matthew:

If you do that then when the cooling call is over at the thermostat the indoor blower will go off and the outdoor unit will keep on running. This will cause the system freeze up and could potentially cause damage to your outdoor compressor.

Matthew:

Did you try putting the wire under Y at the thermostat under the R terminal with the wire already there and see if the outdoor unit comes on?

Matthew:

Try that, and it could be a bad thermostat.

Customer:

Which one RC or RH?

Matthew:

It doesn't matter they should be bridged together. They have a jumper connecting them right?

Customer:

Yes indeed.

Matthew:

Yeah either one!

Customer:

It’s working.

Customer:

Outside and inside both kicked on.

Matthew:

You’ve got a thermostat problem.

Matthew:

Is it old?

Customer:

It’s only 5 yrs.

Matthew:

Is it digital?

Customer:

Yes!

Matthew:

Make sure that wire under Y is good and tight. Make sure the jumper from RH to RC is good and tight. If the red wire is under RH and the jumper comes loose from RC the cooling will not work.

Matthew:

RH=24v for heating call RC=24v for cooling call.

Matthew:

If it still doesn't work then you need a new thermostat.

Matthew:

You can leave the Y wire under the R terminal and have cooling but it will stay on until you cut high voltage or take the Y wire out.

Matthew:

Just get your home nice and cold then shut it off and go to bed for the night.

Customer:

What should I do tomorrow to fix this?

Matthew:

Or go to home depot now and get a new thermostat.

Matthew:

Just get a new thermostat and you should be good to go.

Matthew:

Turn off the high voltage to the furnace when you swap them out.

Customer:

Oh, I can purchase this from home depot?

Matthew:

The red wire is the only one that is hot but it is best to turn off power to furnace then change them.

Matthew:

Yeah and it will be wire for wire you sound like you have a gas furnace system so it will just be the 4 wires red, green, yellow, and white.

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