Rotron Blower Motor Troubleshooting

Posted by Optimal Tech on


Rotron Troubleshooting

Blower Disassembly

WARNING: Attemping to repair or diagnose a blower may void Rotron's warranty. It may also be difficult to successfully disassemble and reassemble the unit.

1. Disconnect the power leads. CAUTION: Be sure the power is disconnected before doing any work whatsoever on the unit.

2. Remove or seperate piping and/or mufflers and filters from the unit

3.Remove the cover bolts and then the cover. NOTE: Some units are equipped with seals. It is mandatory that these seals be replaced once the unit has been opened. 

4. Remove the impeller bolt and washers and then remove the impeller. NOTE: Never pry on the edges of the impeller. Use a puller as necessary. 

5. Carefully note the number and location of the shims. Remove and set them aside. NOTE: If the disassembly was for the inspection and cleaning, the unit may now be reassembled by reversing the above steps. If motor servicing or replacement and/or impeller replacement is required the same shims may not be used. It will be necessary to re-shim the impeller according to the procedure explained below. 

6. Remove the housing bolts and remove the motor assembly (arbor/housing on remote drive models).

7. Arbor disassembly (Applicable on remote drive models only):

a) Slide the bearing retaining sleeve off the shaft at the blower end

b) Remove the four (4) screws and the bearing retaining plate from the blower end

c) Lift the shaft assembly far enough out of the arbor to allow removal of the blower end snap ring.

d) Lift the shaft assembly from the arbor

e) If necessary, remove the shaft dust seal from the pulley end of the arbor. 

 Muffler Material Replacement

1. Remove the manifold cover bolts and them manifold cover.

2. The muffler material can now be removed and replaced if necessary. On blowers with fiberglass acoustical wrap the tubular retaining screens with the fiberglass matting before sliding the muffler pads over the screens.

3. Reassemble by reversing the procedure. NOTE: On DR068 models with tubular mufflers it is necessary to remove the cover and impeller accessing the muffler material from the housing cavity.

Blower Reassembly

1. Place the assembled motor (assembled arbor assembly for remote drive models) against the rear of the housing and fasten with the bolts and washer.

2. To ensure the impeller is centered within the housing cavity re-shim the impeller according to the procedure outlined below.

3. If blower had a seal replace the seal with a new one.

4. Place the impeller onto the shaft making sure the shaft key is in place and fasten with the bolt, washer and spacer as applicable. Torque the impeller bolt per the table below. Once fastened carefully rotate the impeller to be sure it turns freely.

5. Replace the cover and fasten with bolts.

6. Reconnect the power leads to the motor per the motor nameplate.

 Bolt Size



1/4-20 6.25 +/- 0.25
5/16-18 11.5 +/- 0.25
3/8-16 20.0 +/- 0.5
1/2-13 49.0 +/- 1
5/8-11 90.0 +/- 2


Impeller Shimming Procedure

WARNING: This unit may be difficult to shim. Extreme care may be exercised.

Tools Needed: Machinist’s Parallel Bar

Vernier Caliper with depth measuring capability

Feeler gauges or depth gauge

Measure the Following:

Distance from the flange face to the housing (A)

Distance from the flange face to the motor shaft shoulder (B)

Impeller Thickness (C)

Measurements (A) and (B) are made by laying the parallel bar across the housing flange face and measuring to the proper points. Each measurement should be made at three points, and the average of the readings should be used.

Shim Thickness = B – (A+C)/2

After the impeller installation (step #4 above) the impeller/cover clearance can be checked with feeler gauges, laying the parallel bar across the housing flange face. This clearance should nominally be (A-C)/2.

Rotron Shims
Information provided by Ametek DFS

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