Tom's Life Bits

Fan Jet uses a 3L270 belt.

The fan belt tension can be adjusted from the outside or inside the greenhouse. It's easiest to adjust from the inside since the fan blade interferes when adjusting from the outside. To adjust from the outside, the guard screen must be removed. The guard screen on house 1 and 2 is fastened with self tapping screws requiring a 3/8“ socket to remove. To adjust from the inside the guard screen must be removed by flipping the four clips up which are located along the top. It may be necessary to remove the 21 foot long crossbar pipe which goes across the front of the guard and shutter assembly. Once the inside guard is removed, the shutter assembly slides upward and out on houses 1 and 2 and just out on houses 3 and 4. The shutter on houses 3 and 4 is attached with 4 turnbuckles which must be rotated 90 degrees before the shutter can be removed. I have been successful at removing the shutter from the inside without removing the above mentioned crossbar but clearances are tight and the job is even harder if there are plants on the table in front of the fan shutter.

After access has been attained to the belt, the four mounting screws need to be loosened half a turn with a 1/2 inch open end wrench. A socket will not fit on these nuts. The nuts in question are the ones directly under the motor body fastening the feet of the motor frame to the adjuster plate. Do not loosen the four bolts attaching the adjuster plate to the green fan housing. These are fixed in position and should remain tightened. It is a good idea to inspect these bolts to insure they have not become loose.

When the four motor mount feet nuts are loosened, use a 9/16 socket on the adjuster nut which is on the side of the adjuster plate perpendicular to the motor body. Turn this bolt in the direction that makes the motor assembly move away from the fan shaft, thus tightening the belt.

If the belt needs replacing it is a Dayco top cog V belt model 55535 which is 53.5 inches long (length not verified by me, this is info from Advance Auto). Using trial and error, I found that the 4L type belt which is 1/2” wide fits perfectly. The numbers after 4L indicate the beltlength so a 4L550 is 55“ long. I put this belt successfully in house #2.

After the belt is tight, tighten the four bolts on the motor feet with a 1/2 inch open end wrench and then re-assemble the shutter and guard screens.

Concise summary of above steps:

1. Remove fan screen guards. Outside guard on house 1 and 2 uses 3/8 inch socket.
2. Loosen four motor mounts with 1/2 inch open end wrench.
3. Check that the four bolts attaching the gray adjuster plate to the green fan housing are tight.
4. Use a 9/16 inch socket and turn the adjuster nut on the side of the adjusting plate to tighten the belt
5. Tighten the four motor mounting feet nuts with a 1/2 inch open end wrench
6. Re-assemble the shutter and guard assembly.

This is a compendium derived from the google maintenance blog.

• March 2007, House 2, 4L540
• April 2007, House 3 MBL Corp 4L550
• July 2007 House 3, 4L550