testo 550 Digital Manifold

with Bluetooth/App

Temperature port on each side

2 line, back lit LCD display

Control keys

Pressure zeroing

Escape Key

3 x 1/4” SAE connections

Show Min/Max/Mean values

Valve knobs

Min, Max and Mean

Warranty

Troubleshoot,

evacuate, charge

AC, heat pump or

auto mode

Conduct leak test

The testo 550 has a two year warranty. If registered, the warranty is extended to 5 years.

Pic. 16

Arrow keys

Power On/Off

Backlight

Bluetooth Activation

The testo 550 now comes standard with Bluetooth.

1. First turn on the testo Refrigeration App on

your smart device.

2. Once the app is running, turn on the testo

550.

3. Press and hold the UP and DOWN arrow

simultaneously to activate Bluetooth.

4. The Bluetooth icon will flash to the left of the

battery display icon and remain on once

bluetooth is activated. (Pic. 16)

5. The app will now show your 550 as an

available device. (Pic 17)

6. Select your instrument in the app to pair your

device.

Pic. 17

The testo 550 offers the ability to display Min, Max

and Mean measurement values.

1. Simply press the Min/Max Mean button to cycle

this setting.

2. Pressing this button once will display the Min

setting.

3. Pressing the button twice will display the Max

setting.

4. Pressing the button three times will display the

Mean setting.

5. Pressing the button a fourth time will return the

setting to the standard measurement display

Changing the batteries

Testo 550 uses 4x 1.5 V, AA batteries.To

replace the batteries please follow these

few steps below:

1. Fold out the hook (Pic. 1).

2. Grab the clip and squeeze it

together and remove the cap (Pic.

2).

3. Insert/Change the batteries.

Observe the polarity.

Power ON / OFF

1. Connect probes to the testo 550 prior

to powering it up.

2. Press the power button [ ] to turn

the testo 550 on.

3. All display segments will light up for

2 seconds.

4. Measurement view is then displayed

5. Press and hold the power button to

turn the testo 550 off.

Choose the refrigerant

Set the Units / Altitude / Mode

1. Press the [Set] button once to get to the

temperature units menu (Pic. 4). Choose

the required units with the arrow keys.

3. Press the [Set] button again to view the

pressure units (Pic. 5). Choose the desired

units with the arrow keys.

4. Press the [Set] button again to select

absolute or relative pressure (Pic. 6)

5. Press[Set] again so that you can set the

barometic pressure in

inHg (Pic. 7) .

6. Press the [Set] button again to select the

AC/R [ ], heat pump [ ], or Auto [ ].(Pic

8). Auto mode senses if the Low pressure

side is 15 psi higher than the High pressure

side, and will automatically reserve the

display of the High / Low side pressures

7. Press the [Set] button again to set the

Auto Off Feature. Setting this On will allow

the 550 to power down automatically when

not in use.

8. Press [Set] a final time to turn the Tfac

on or off using the arrow keys. (Pic. 9)

9. Press the [Esc] button to exit the settings

menu.

Backlight

Testo 550 has a backlight to

improve viewing in dark or

daylight conditions. Press the

backlight button to turn the

backlight on. Press it once again

to turn the backlight off.

Pressure zeroing

The pressure sensors should be zeroed before each

use.

1. Loosen the hose connections

2. Open the valve knobs to confirm that there is

no pressure in the manifold

3. Press the [p=0] button and the sensors will

display zero pressure.

Leak Test

The temperature compensated leak test is used to

indicate leaks in an AC/R or heat pump system.

1. Plug in the temperature probe into the high side of

the instrument.

2. Press the set button 6 times to reach the Tfac setting.

Press the UP arrow to cycle this setting to OFF.

Press SET to select this setting

3. Zero the pressure sensors.

4. Connect the testo 550 to the system.

5. Press the [Mode] button once to get to the leak test

mode (Pic. 14).

6. Now press the [R, Start/Stop] button to start the

test. (Pic. 15).

7. The test duration depends on the system size.

8. Press [R, Start/Stop] again to stop the test.

9. The results will be displayed.

10. Press the [Mode] button twice to return to the

normal measurement mode. Please make sure to

repeat step 2 to turn the Tfac back to ON before

starting normal testing again.

Note: rP could be different from the

starting and final test pressure rP as the

true rp is calculated from the gas laws.

Pic. 15

Pic. 14

Pic. 13

Pic. 12

Pic. 11

Pic. 10

Pic. 7

Pic. 6

Pic. 5

Pic. 4

Pic. 3

Pic. 2Pic. 1

Pic. 8

Superheat and Sub-cooling

The testo 550 calculates superheat and sub-cooling in

real time.

1. Connect the temperature probes and hoses to the 550.

2. Turn on the instrument.

2. Connect the testo 550 and the pipe clamp probes to

the air conditioning, refrigeration or heat pump system.

3. You will now see the calculated evaporation and

condensation temperature (Ev and Co) and system

pressures at the top of the display. (Pic. 10)

4. Press the UP-arrow once to see the temperature

difference (Pic. 11)

5. Press the UP-arrow twice to see the real time

superheat and sub-cool (SH and SC) (Pic. 12).

6. Press the UP-arrow for the third time to see the real

time measured temperature (T1 and T2) (Pic. 13).

7. Press the UP-arrow again to get back to the calculated

evaporation and condensation temperature. You can

also use the DOWN-arrow to switch between the menus

but the order will be reversed.

1. Press the [R, Start/Stop] button to bring

up the refrigerant selection screen (Pic. 3).

2. Use the arrow keys to scroll through the

refrigerant choices.

3. Press the [R, Start/Stop] button to set the

desired refrigerant.

Pic. 9