Auto Fan

When the fan speed is set to Auto, the fan will run at either the medium or low speed based on the difference between the room temperature and the set point temperature as shown below:

Low. Speed

Room te

m

p. down

 

 

 

 

 

 

 

 

 

 

 

 

 

Room

te

mp. up

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Med. Speed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Defrost

Defrost on heat pump units is controlled by the microprocessor and is initiated if either of the following conditions occur:

1.The outdoor coil temperature is lower than 32_F (0_C) for more than 40 minutes and during that period, the coil temperature is continuously lower than 26.6_F (-3_C) for 3 minutes.

2.If the first condition does not occur within 90 minutes of termination of the last defrost cycle.

The defrost cycle will terminate 10 minutes after initiation or when the coil temperature reaches 68_F (20_C). At the end of the

T = Room Temperature Ts = Set Point Temperature

0 3.6°FT-Ts

A08112

Defrost cycle the timer resets automatically.

The cycles of defrost algorithm are shown below:

Defrost 10 or 6 minutes

Fig. 28 – Auto Fan - Heating Mode

Manual Indoor Fan

The indoor fan will run continuously in heating at the set fan speed (even if the compressor cycles off) unless the indoor coil temperature begins to drop. When the coil temperature drops to the TE3 limit, the 18k and 24k unit indoor fan switches to low speed. On the 9k and 12k unit the indoor fan switches to ultra low speed. When the coil temperature drops to the TE4 limit, the indoor fan on all systems shuts off to prevent cold blow as shown below. The cold blow algorithm also applies to the auto fan setting.

Compressor

4-way valve

Outdoor fan

Indoor fan

On

Off

5s

25s

2s

38/40MVC, MVQ

 

 

 

 

 

 

 

 

 

 

 

Set fan speed

 

 

 

 

 

 

 

 

 

 

 

 

 

Low Speed /

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ultra Low Speed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T tem

p.

down

 

 

 

 

 

 

 

 

 

T tem

p. up

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(Coil temp.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fan off

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TE4

TE1

TE3 TE2

 

T

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A08111

 

 

 

 

Fig. 29 – Manual Indoor Fan - Heating Mode

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Parameter

 

 

Indoor Coil Temperature ˚F (˚C)

 

 

40MVQ

 

 

40MVQ

 

 

40MVQ

 

 

 

40MVQ

 

 

 

 

 

 

 

009---1

 

 

 

012---1

 

018---3

 

024---3

 

 

TE1

88 (31)

 

 

 

88 (31)

 

77 (25)

 

82 (28)

 

 

TE2

93 (34)

 

 

 

91 (33)

 

90 (32)

 

93 (34)

 

 

TE3

86 (30)

 

 

 

81 (27)

 

86 (30)

 

90 (32)

 

 

TE4

72 (22)

 

 

 

68 (20)

 

68 (20)

 

75 (24)

 

Sleep Mode

When in heating mode additional energy savings can be realized by selecting the Sleep setting. When the Sleep setting is selected, the temperature set point is adjusted automatically as shown below:

Set Point

 

 

1.8ºF

 

 

 

1.8ºF

 

1

2

Time (hour)

A08110

Fig. 30 – Sleep Mode - Heating

The unit will shut off 7 hours after the Sleep mode is selected.

10s

A08114

Fig. 31 – Defrost Cycle

Auto Mode

When the Auto setting is selected, the microprocessor looks at the difference between the room temperature (T) and the set point (TS). The algorithm determines which mode the unit will run in as shown below:

Heating (fan only in cooling)

Fan only

Cooling

 

 

 

-1.8°F 3.6°F T-TS

A08115

Fig. 32 – Auto Mode

When the unit shifts modes, it will remain in that mode for at least 15 minutes while the algorithm ignores the difference between T and TS. This ensures that the unit cannot change modes too frequently.

23

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Carrier 40MVQ, 40MVC, 38MVQ, 38MVC service manual Auto Fan, Defrost

40MVQ, 40MVC, 38MVQ, 38MVC specifications

The Carrier 38MVC, 38MVQ, 40MVC, and 40MVQ are advanced air-conditioning systems designed for both residential and commercial applications. These units are recognizable for their commitment to efficiency, reliability, and comfort, making them ideal choices for various environments.

One of the standout features of these models is their high energy efficiency ratings. Both the 38MVC and 38MVQ boast Seasonal Energy Efficiency Ratios (SEER) that exceed industry standards, delivering substantial energy savings over time. The 40MVC and 40MVQ models also continue this trend, featuring enhanced efficiency that translates into lower utility bills and a reduced carbon footprint.

These air-conditioning units utilize Carrier's innovative inverter technology, which allows for variable speed operation. This means that the compressor can adjust its speed according to the cooling demand, resulting in smoother temperature control and less energy consumption. The inverter technology not only maximizes comfort but also contributes to quieter operation, as the systems can run at lower speeds when full capacity is not required.

In addition to efficiency, the Carrier 38MVC, 38MVQ, 40MVC, and 40MVQ are equipped with advanced filtration systems. These systems work to purify the air by reducing allergens and pollutants, ensuring a healthier indoor environment. Some models also come equipped with smart connectivity options, allowing users to control their air conditioning remotely via a smartphone app. This feature adds convenience and helps monitor energy usage effectively.

With durable construction and high-quality components, these units are designed to withstand the test of time, reducing the need for frequent repairs or replacements. They are also built to operate quietly, so they can provide comfort without disturbing the peace of the indoor environment.

In terms of installation flexibility, the Carrier 38MVC, 38MVQ, 40MVC, and 40MVQ can be easily integrated into various existing HVAC systems, thanks to their compatible size and design. This adaptability makes them suitable for a wide range of applications, from small residential homes to larger commercial spaces.

Overall, the Carrier 38MVC, 38MVQ, 40MVC, and 40MVQ models are engineered with cutting-edge technologies that prioritize efficiency, comfort, and ease of use, making them an excellent choice for those looking to enhance their indoor climate control solutions.