Charging the System 90MU | Carrier 90MA manual

Charging the System (90MA) - These units are shipped with a full operating charge. If recharging is necessary (complete charge lost), weigh in amount of refrigerant indicated on unit nameplate and in Table 1.

If unit has partial charge, it must be recharged by removing existing charge and recharging by weighing in the required amount of refrigerant. (Refer to Table 1A/B/C/2A/B/C)

Charging the System (90MU)

UNIT SIZES 90MU Units - These units, used with remote condensers, are shipped with a holding charge only. To charge:

1.Open discharge and liquid service valves.

2.Leak test, reclaim refrigerant and evacuate.

3.Using standard refrigerant charging techniques and subcooling charts (Figure 11) add refrigerant as required to maintain proper operating conditions. Subcooling is determined by subtracting the actual temperature entering the TXV from the saturated temperature entering the TXV.

IMPORTANT: Charge on both the HIGH and LOW side simultaneously of idle compressors to prevent axial loading of the scroll, which may cause a temporary no start condition for the compressor. If this occurs, leave the system off for approximately 30 minutes. Attempt to restart the compressor; internal pressures should equalize enough to allow compressor to start.

If removing the compressor, evacuate both the HIGH and LOW side simultaneously.

Required		R407C PRESSURE AT LIQUID LINE SERVICE VALVE										PSIG
Subcooling (ºF)	137	149	162	176	205	222	239	256	275	295	315		336	359
0	70	75	80	85	90	95	100	105	110	115	120		125	130
5	65	70	75	80	85	90	95	100	105	110	115		120	125
10	60	65	70	75	80	85	90	95	100	105	110		115	120
15	55	60	65	70	75	80	85	90	95	100	105		110	115
20	50	55	60	65	70	75	80	85	90	95	100		105	110
25	45	50	55	60	65	70	75	80	85	90	95		100	105

Required		R404A PRESSURE AT LIQUID LINE SERVICE VALVE										PSIG
Subcooling (ºF)	150	163	176	190	205	221	237	255	273	292	313		334	356
0	70	75	80	85	90	95	100	105	110	115	120		125	130
5	65	70	75	80	85	90	95	100	105	110	115		120	125
10	60	65	70	75	80	85	90	95	100	105	110		115	120
15	55	60	65	70	75	80	85	90	95	100	105		110	115
20	50	55	60	65	70	75	80	85	90	95	100		105	110
25	45	50	55	60	65	70	75	80	85	90	95		100	105

Required		R407C PRESSURE AT LIQUID LINE SERVICE VALVE										kPa
Subcooling (ºC)	1100	1200	1300	1400	1500	1600	1700	1800	1900	2000	2100	2200	2300
0	23	26	29	32	34	37	39	42	44	46	48	50	52
3	20	23	26	29	31	34	36	39	41	43	45	47	49
5	18	21	24	27	29	32	34	37	39	41	43	45	47
7	16	19	22	25	27	30	32	35	37	39	41	43	45
10	13	16	19	22	24	27	29	32	34	36	38	40	42
13	10	13	16	19	21	24	26	29	31	33	35	37	39

Required		R404A PRESSURE AT LIQUID LINE SERVICE VALVE										kPa
Subcooling (ºC)	1190	1288	1392	1503	1580	1701	1786	1918	2011	2107	2206	2308	2414
0	23	26	29	32	34	37	39	42	44	46	48	50	52
3	20	23	26	29	31	34	36	39	41	43	45	47	49
5	18	21	24	27	29	32	34	37	39	41	43	45	47
7	16	19	22	25	27	30	32	35	37	39	41	43	45
10	13	16	19	22	24	27	29	32	34	36	38	40	42
13	10	13	16	19	21	24	26	29	31	33	35	37	39

FIGURE 11 - CHARGING CHARTS

Evaporator-Fan Motor Removal - Motor power wires need not be disconnected from motor terminals before motor is removed from unit.

1.Shut off unit main power supply.

WARNING

LOCK OPEN AND TAG unit disconnect before working on fan motor. Remove fuses and take them with you after noting this on tag.

CAUTION

Before attempting to remove fan motors or motor mounts, place a piece of plywood over evaporator coils to prevent coil damage.

2.Loosen motor hold down bolts on mounting bracket so that fan belt can be removed.

3Loosen but do not remove the 2 motor mounting bracket bolts on left side of bracket.

4Slide motor/bracket assembly to extreme right, remove bolts and lift out through space between fan scroll and side Rest motor on a high platform such as a step ladder. Do not allow motor to hang by its power wires.

Pressure Relief Device - All units are equipped with a fusible-plug type safety relief device an the refrigerant tubing. The relief setting is 197 °F to 203 °F on all units.

Crankcase Heater - A Crankcase heater is supplied on 90MA,MU*08 and *12 size units. The heater prevents liquid refrigerant from accumulating in the compressor crankcase during extended shutdown periods. Heater is automatically energized whenever unit main power is on and compressor is stopped. Heater is de-energized when compressor starts.

Do not shut off main power supply for an extended period except for servicing unit. Turn on power supply for at least 24 hours after an extended shutdown before starting compressor. Refer to “Operation”.

Cycle-LocTM- Protection Device - All units are equipped with Cycle-LOCcurrent-sensing lockout relay. This device will lock out the compressor after any safety trip (discharge pressure switch, suction-pressure switch, or internal overload of the compressor). Check reason for lockout before resetting the device. Refer to unit label wiring diagram. To reset, turn the system switch to OFF, then back to COOL.

Discharge and Suction Pressure Switches - Refer to Table 1 for opening and closing settings for these safety devices.

The discharge pressure switch is located on the compressor on 06DA compressor equipped units and on the discharge line on all other units. The suction pressure switch is located on top of the compressor on 06DA

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations

Printed in U.S.A.	Pg 15	90MA-3SI SUPERCEDES FORM 62-02971-00 09-2009
	Pg 15