Carrier 07D - Manual (Page 27)

INSTALLATION
06D,07D
crack open the liquid test cock. The charge
is sufficient if a mixture of liquid and vapor
comes from the test cock.
The sight glass method of checking the re­
frigerant charge is more reliable, and should
be used whenever possible.
6. When the system is sufficiently charged, close
the valve to the refrigerant cylinder, back­
seat the suction shut-off valve, disconnect
the charging line, plug the gage ports, and
recap the valve stems. If the pressure in
the cylinder drops to the level of the suction
pressure, all refrigerant can be drawn from
the cylinder by frontseating the suction shut­
off valve and pulling a vacuum on the cylinder.
CAUTION: Be careful not to overcharge the sys­
tem, Overcharging results in:
1. Higher discharge pressure due to excess liq­
uid in the condenser. With water-cooled units
this means higher cooling water consumption.
2. Possible compressor damage,
3. Higher power consumption,
4. Increased flooding of refrigerant to the com­
pressor during off-cycle if the expansion
valve is leaky.
To charge the system thru the liquid line, refer
to the Service Section of the Product Informa­
tion Book.
3. Open the compressor discharge and suction
shut-off valves,
4. Open the liquid line valve at the receiver.
5. Open pressure line valve of the water reg­
ulating valve.
6. Close the main power switch supplying cur­
rent to the compressor starter,
7. Check the oil pressure. (See "Lubrication.")
8. Adjust the water regulating valve.
9. Check control settings.
10. Recheck the oil level in the crankcase.
11. Cap all valves tightly.
CHECKING OPERATIONS
When starting a newly Installed compressor, be
on the alert for any sign of trouble. Always in­
stall suction and discharge pressure gages. The
water regulating valve on water-cooled units
may need adjustment.
Dual Pressurestat
A dual pressurestatis connected to both the high
side and low side to protect the compressor.
Settings are preset at the factory for use with
R-12 or R-22 as shown by the values in Table 6.
INITIAL START-UP INSTRUCTIONS
The compressor should be started up only by
a refrigeration mechanic who is familiar with
accepted operation practices for refrigeration
systems. Detailed instructions for checking and
adjusting the components will be found under
"CHECKING OPERATIONS."
Proceed as follows:
Water-Cooled Units
1, Check to see that the proper oil level appears
in the compressor sight glass, (A dipstick
must be used with two cylinder compres­
sors.) See "Lubrication" under "CHECK­
ING OPERATIONS,"
2, Open the main water supply valve and allow
water to reach the condenser.
Table 6 - Factory Pressurestat Settings (Psig)
High Pressure Low Pressure
Unit Cutout Cut-in Cutout Cut-in
07D Units 280 200 36 67
U6U Units 370 290 36 67
The 07D condensing unit high pressurestat cut­
out point is adjustable from 230-340 psig with
a fixed differential. The 06D compressor unit
high pressurestat cutout point is adjustable from
230-400 psig with a fixed differential. The low
pressurestat on all units have an adjustable cut­
out from 20" vacuum to 70 psig and an adjust­
able differential from 13-50psi. All adjustments
are made thru the back of the control box.
Check the high-pressure cutout by throttling
the condenser water on water-cooled units, or
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