The parent unit does not recognize that the nursery unit is on. all the correct lights are displayed on the nursery unit for normal function, but the parent unit display indicates that the nursery unit is not on, and therefore cannot communicate with it. This results in the parent unit giving a series of warning beeps and then switching off.

Hi

We found this online that may help http://www.ehow.com/how_7553536_instructions-graco-imonitor.html If not we recommend contacting Graco customer care.

I had the same thing happen to one of my parent units over the weekend. The issue is that the parent unit lost the pairing with the nursery unit. Once I re-paired them, it's working great again. This is in the Troubleshooting part of the manual, but I've copied below for your convenience.
If Parent Unit won't lock onto the Nursery Unit, or you purchased a new Nursery Unit, follow the procedure below to pair the Parent Unit and Nursery Unit. If you purchased a new Parent Unit, skip Step 1. The new Parent Unit is ready to pair with your Nursery Unit.
1. Erase the Pairing from the Parent Unit. Turn the Parent Unit off. Hold the Volume Down Button on the Parent Unit while pressing the On/Off Button. Continue to hold the Volume Down Button until you hear a single beep and all of the Sound Lights illuminate briefly. Release the Volume Down Button. Press and hold the Volume Down Button again. Within 2 seconds you will hear a beep. Release the Volume Down Button. All of the SoundLights and the red Loss Connection LED will be lit. The Parent Unit is ready to pair with Nursery Unit. 2. Pair the Parent Unit with Nursery. Place Nursery Unit in the same room, five (5) feet (1.5 meters) away from the Parent Unit. Turn on Nursery Unit using the On/Off Button on the side. The green power light should come on. Within a few seconds, the Parent Unit will find the Nursery Unit. The SoundLights will shut off and the Parent Unit will beep. The Parent Unit is now paired with Nursery Unit. 3. Repeat this procedure if you need to pair another Parent Unit with the Nursery Unit.
Nothing happened when I turned on the Nursery Unit. What do I do? First try turning the Nursery Unit off, and then on again. If the Parent Unit still does not pair with the Nursery Unit, press the Channel Button on the Nursery Unit, then turn the Nursery Unit off, and then on again.
Hope this helps.

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Had exactly the same problem but this worked. Never even realised there was a button on the top of the unit!!! It looks like a little LED at the base of the hoop. Happy monitoring.

CONNECTING THE PARENTS UNIT TO THE NURSERY UNIT:
If you lose the connection between the 2 units,turn them both off. Turn ON the parents unit and
press and hold the MENU button ,the "out of range"indicator will flash and you will hear a
beep.Turn ON the nursery unit and press and hold the top button of the nursery unit to reconnect.
The Tic light flashes.This normally happens within a few seconds and you will hear a bleep
to confirm it. If successful, the parents unit display will first show the channel of transmission (C1
to C8), which will be replaced by the room temperature and icons for all activated functions.
Note : The connecting process should be done within 30 seconds. If longer, the operation will be
ignored and you will have to start over.
• PAGING: If you want to locate the parents unit, press the top button of the nursery unit.

I have the same problem. I'm guessing mine is broken and will need to be replaced. However i did read a possible solution on a site with slightly different instructions to the ones in the box that describes how to pair the two devices together.

turn both the nursery and parent units off.
turn on the parent unit.
hold menu for 5 secs until it beeps.
turn on the nursery unit.
the parent unit waits for the signal then pairs.

if the nursery unit just waits 20 seconds then beep beep beeps and turns off i guess yours is broken too. I think its probably the nursery unit has stopped transmitting.

they will replace or repair a unit that less than 12 months from date of purchase with a supporting receipt.

the help line is 0845 009 1789 mon-fri 11-3pm

Manuals: http://www.angelcare-monitor.com/Canada/en/help
Had same problem - here's what worked for AC401 (from manual):
CONNECTING THE PARENTS UNIT TO THE NURSERY UNIT: If you lose the connection between the 2 units,turn them both off. Turn ON the parents unit and press and hold the MENU button ,the "out of range"indicator will flash and you will hear a beep.Turn ON the nursery unit and press and hold the top button of the nursery unit to reconnect. The Tic light flashes.This normally happens within a few seconds and you will hear a bleep to confirm it. If successful, the parents unit display will first show the channel of transmission (C1 to C8), which will be replaced by the room temperature and icons for all activated functions.

Manuals here: http://www.angelcare-monitor.com/Canada/en/help#tabs-2
Had same problem - here's what worked for AC401 (from manual):
CONNECTING THE PARENTS UNIT TO THE NURSERY UNIT: If you lose the connection between the 2 units,turn them both off. Turn ON the parents unit and press and hold the MENU button ,the "out of range"indicator will flash and you will hear a beep.Turn ON the nursery unit and press and hold the top button of the nursery unit to reconnect. The Tic light flashes.This normally happens within a few seconds and you will hear a bleep to confirm it. If successful, the parents unit display will first show the channel of transmission (C1 to C8), which will be replaced by the room temperature and icons for all activated functions.

The units aren't paired. Call Graco at 800-345-4109 to have them walk you through pairing it. I'll try to explain what they just walked me through:

-Turn off all units. Make sure nursery and 1st parent unit is plugged directly into wall.
-Hold negative volume down on 1st parent unit. Keep holding it down.
-Press on button on 1st parent unit and let go.
-When you hear a beep, let go of negative volume button on 1st parent unit and then press it again.
-When you hear the second beep, let go of the negative volume button.
-If you have done it correctly, the 1st parent unit should have one red light at the bottom and the rest of the lights should be green.
-Turn on nursery unit and the 1st parent unit should pair with it.
-Repeat the above with the 2nd parent unit.

Manuals here: http://www.angelcare-monitor.com/Canada/en/help#tabs-2
Had same problem - here's what worked for AC401 (from manual):
CONNECTING THE PARENTS UNIT TO THE NURSERY UNIT: If you lose the connection between the 2 units,turn them both off. Turn ON the parents unit and press and hold the MENU button ,the "out of range"indicator will flash and you will hear a beep.Turn ON the nursery unit and press and hold the top button of the nursery unit to reconnect. The Tic light flashes.This normally happens within a few seconds and you will hear a bleep to confirm it. If successful, the parents unit display will first show the channel of transmission (C1 to C8), which will be replaced by the room temperature and icons for all activated functions.

Manuals here: http://www.angelcare-monitor.com/Canada/en/help#tabs-2
Had same problem - here's what worked for AC401 (from manual):
CONNECTING THE PARENTS UNIT TO THE NURSERY UNIT: If you lose the connection between the 2 units,turn them both off. Turn ON the parents unit and press and hold the MENU button ,the "out of range"indicator will flash and you will hear a beep.Turn ON the nursery unit and press and hold the top button of the nursery unit to reconnect. The Tic light flashes.This normally happens within a few seconds and you will hear a bleep to confirm it. If successful, the parents unit display will first show the channel of transmission (C1 to C8), which will be replaced by the room temperature and icons for all activated functions.

Try the manuals: http://www.angelcare-monitor.com/Canada/en/help#tabs-2
The picture showing looks like the AC201 which has a hard switch for the channel selection, but you describe a menu screen which sounds like the AC401 or similar. If it is the AC201 - ensure both units are on the same channel. If it is the AC401 or other unit where there is an LCD, then try the following:
CONNECTING THE PARENTS UNIT TO THE NURSERY UNIT: If you lose the connection between the 2 units,turn them both off. Turn ON the parents unit and press and hold the MENU button ,the "out of range"indicator will flash and you will hear a beep.Turn ON the nursery unit and press and hold the top button of the nursery unit to reconnect. The Tic light flashes.This normally happens within a few seconds and you will hear a bleep to confirm it. If successful, the parents unit display will first show the channel of transmission (C1 to C8), which will be replaced by the room temperature and icons for all activated functions.