Heat Controller VMH09SC-1, VMH12SC-1, VMH24SC-1, VMH18SC-1 service manual VMH Series, While

Service Manual VMH Series Heat Controller, Inc.

After A/C starts up, the compressor will run at the Fmax frequency for 7 minutes according to outdoor ambient temp. During the 7 minutes, frequency limitation is active.

7 minutes later, compressor running frequency will be controlled as below:

T1-Ts-ΔT
°F	°C
41	(+5.0)
40	(+4.5)
38	(+3.5)
37	(+3.0)
37	(+2.5)
36	(+2.0)
35	(+1.5)
34	(+1.0)
33	(+0.5)

While

Temp. zone	A	B	C	D	E	F	G
Frequency	F10	F9	F8	F7	F5	F3	F4

ΔT=32°F/0°C as default.

Note:

When T1-Ts stays in the same temp. zone for 3 minutes, the compressor will run as follows: A~E: Increase the frequency to the higher level F10.

F:Keeps the current frequency.

G:Decreases the frequency to the lower level F1.

H:Runs at F1 for 1h. (If T1-Ts-ΔT >43°F/6°C, compressor will stop)

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