Friedrich SH15L30-B Benutzerhandbuch

6

A cross ambient thermostat is used to maintain the desired 

comfort level. The thermostat reacts only to a change in 
temperature at the bulb location. Important to the successful 
operation of the unit is the position of the sensing bulb in relation 
to the evaporator (see Figure 8).

Remove the wires from the thermostat. Turn the thermostat to 
its coldest position. Check to see if there is continuity between 
the two terminals. Turn the thermostat to its warmest position. 
Check continuity to see if the thermostat contacts open.

Note: The temperature must be within the range listed to check 
the thermostat. Refer to the troubleshooting section in this 
manual for additional information on thermostat testing.

The HazardGard unit is designed to operate at low outside 

ambient temperatures. This is accomplished by the use of a 
bypass valve installed in the refrigeration circuit. The valve 
is connected between the discharge line at the compressor 
and the suction process tube. The valve responds to suction 
pressure which, when reduced in the system, causes the 
valve to open and bypass hot gas from the high pressure side 
to the low pressure side of the system. The hot gas entering 
the compressor mixes with the cool gas returned through the 
suction line, thus increasing the suction pressure. The valve 
is preset to open when the suction pressure reaches 50 psig. 

This pressure setting cannot be altered. The system can be 

operated at outdoor temperatures as low as 45°

 

F before the 

evaporator coil will begin to accumulate frost.

To determine if the valve operates, block the return air to the 

evaporator coil. Turn on the unit and touch the tube at the 
bypass valve outlet which connects to the suction process 
tube. When the low side pressure reaches approximately 50 
psig, the valve will begin to open and the tube will get hot. This 
method will determine if the valve is responding to the suction 
pressure change.

1. Voltmeter

2. Ammeter

3. Ohmmeter

4.  E.P.A Approved Refrigerant Recovery System

5.  Vacuum Pump (capable of 200 microns or less vacuum).

6. Acetylene 

Welder

7. 

Electronic Halogen Leak Detector (G.E. Type  

 

H-6 or equivalent).

8.  Accurate refrigerant charge measuring device  

 

such as:

 

a.  Balance Scales - 1/2 oz. accuracy

 

b.  Charging Board - 1/2 oz. accuracy

9.  High Pressure Gauge - (0-400 lbs.)

10.  Low Pressure Gauge - (30" - 150 lbs.)

11.  Vacuum Gauge - (0-1000 microns)

1. 

Recovering CFC’s as low as 5%.

2.  Evacuation from both the high side and low side of the 

system simultaneously.

3. 

Introducing  refrigerant  charge  into  the  high  side  of  the 

system.

4. 

Accurately weighing the refrigerant charge actually intro-

duced into the system.

5. Facilities 

for 

fl owing nitrogen through the refrigeration 

tubing during all brazing processes.

RANGE: Thermostat

(Part No. 618-225-02)

60° F ( ± 2° ) to 90° F( ± 4° )