True or False
You can charge liquid in the liquid line when the system is running
False
Pressure is too great on the high side when the system is running
Adding refrigerant to a system
What is charging
The scale of condensing and vaporizing temperatures for a zeotropic refrigerant blend
What is a temperature glide
Low pressures + high superheat + low subcooling
Low charge
50oz of refrigerant converted to pounds
3.125 pounds
[50\16=3.125]
When charging r-410a the jug is upright
False
up-side-down
Increased system temperatures and operating pressures
What does overcharging a system cause
Liquid line temperature - condenser saturation temperature
What is subcooling
Low suction pressure + normal to high head pressure+ low superheat + normal to high subcooling
Dirty evaporator coil\ reduced airflow
R-22 system
80* ambient temp
70psig, 230psig
SL 55*, LL 98*
What is the superheat and subcooling for this system?
70psig=40* evap. sat. temp
230psig=111* cond. sat. temp.
55-40=15* superheat
111-98=13* subcooling
You have to purge your gauge lines every time before you charge a system
True
Absolutely
Prevents liquid refrigerant from entering a system while charging
What is throttling or using a restrictor
The position of the service valve to allow system operation
What is back-seated
high pressures + low superheat + high subcooling
Overcharge
R-410a
Ambient 75*
100psig, 290psig
SL 50* LL 107*
What is superheat and subcooling?
100psig=31* sat. temp.
290psig=94* sat. temp.
50-31=19* superheat
107-94=13* subcooling
An electronic charging scale and manufacturers charging chart is the most accurate way to charge a system
True
A special valve that keep refrigerant from entering a virgin refrigerant cylinder
What is a check valve
The position of the service valve used when the system is being pumped down
What is front-seated
(on the high side until refrigerant is backed into condenser, then suction line valve is front-seated as well to trap refrigerant in condenser coil)
Normal to low superheat + high saturation temperatures + high subcooling + higher than normal system pressures
Dirty condenser coil
R410a
Ambient 90*
125psig, 350psig
SL 60* LL 115*
What is superheat and subcooling?
125psig=43* evap. sat. temp.
350psig=107* cond. sat. temp.
60-43=17* superheat
115-107=8* subcooling
You can repair a system and not pressure test, change the drier or pull vacuum if you do it quickly on a dry day
FALSE
ALWAYS pressure test, change the drier and pull vacuum every time you open a system
Only Liquid
What is the fastest way to charge a refrigeration system
When you unscrew your service hose at the manifold long enough to get refrigerant out of the line
What is purging
Suction line temperature - evaporator saturation temperature
Superheat
R-22
Ambient 86*
74psig, 250psig
SL 55* LL 120*
What is superheat and subcooling?
74psig=44* evap. sat. temp.
250psig=117* cond. sat. temp.
55-44=11* superheat
120-117=3* subcooling