Picture of Anthony Coker

Anthony Coker

Technical Services Manager
North Georgia District

The Unknown Soldier

Wondering why the VFD is called the Unknown Soldier? It is because it does a lot of work and goes unrecognized. It is one of those things that does its work behind the scenes and doesn’t get recognized until it stops working. Well we are going to give the recognition to this one and maybe by doing so it will have a long and productive life!

VFD

Maintenance of the VFD is critical and can be detrimental when not maintained at specified intervals. The dust can cause overheating and possible damage to the VFD as well causing a shortened life span to the device.

All this information can be found on HVAC Partners under VFD-08SI

VFD Maintenance

If installed in an appropriate environment, the VFD requires very little maintenance.

Table 1 lists the routine maintenance intervals recommended by Carrier

Table 1 - Maintenance Intervals
Table 1 - Maintenance Intervals

Heat Sink Cleaning

The heat sink fins accumulate dust from the cooling air. Check the heat sink annually and if the dust is heaver than usual increase the frequently of cleaning.


Use the following procedure to clean the heat sink on the (AHC550 VFD)
1. Turn off power and (lock out/tag out) unit for your safety and others.
2. To remove the drive cover. Remove the captive screw. (See Figure 1)

Figure 1 – Remove Cover on the (ACH550 VFD)
Figure 1 – Remove Cover on the (ACH550 VFD)

3. Press together the retaining clips on the top cover and lift. (See Figure 2)

Figure 2 – Remove Cover on the (ACH550 VFD)
Figure 2 – Remove Cover on the (ACH550 VFD)

4. Blow clean compressed air (not humid) or dry nitrogen from bottom to top while simultaneously using a vacuum cleaner at the air outlet to recover the dust.

5. Replace the cooling fan.

6. Replace the drive cover.

7. Restore power.

Use the following procedure to clean the heat sink on (ACS320 VFD)

1. Turn off power and (lock out/tag out) unit.
2. To release the top cover, insert a small straight blade screwdriver into the slot and press it in to release. (See Figure 3)

Figure 3– Remove Cover on the (ACS320 VFD)
Figure 3– Remove Cover on the (ACS320 VFD)

3. Blow clean compressed air (not humid air) or dry nitrogen from top of ACS320 while simultaneously using a vacuum cleaner at the base to recover the dust.

4. Replace the top cover.

5. Restore power.

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The new Carrier 27VPA9

February 11, 2026 No Comments

This new unit is a noncommunicating variable 5 speed performance line  heat pump with InteliSense technology, 19 seer2.   Sizes range