Compressor Shaft-Seal Leaks

To determine whether a compressor is leaking at the seal, proceed as follows. Close the shutoff valves by turning the stem clockwise as far as possible. To ensure adequate refrigerant pressure in the compressor crankcase and on the seal-bearing face, attach a refrigerant drum containing the correct refrigerant to the suction shutoff valve outlet port. In making this connection, there should be a gage in the line from the drum to the compressor to determine accurately the pressure in the compressor.

Test pressures for this purpose should be approximately 70 to 80 lb. If the compressor is located in a cool location, it may be necessary to raise the pressure in the drum by adding heat. In this process, care must be taken not to exceed 100 psi, since greater pressure may damage the bellows assembly of the seal. With this pressure on the crankcase of the compressor, test for leaks with a halide torch, moving the finder tube close around the seal nut, crankshaft, seal-plate gasket, and where the seal comes in contact with the seal plate. If this does not disclose a leak, turn the flywheel over slowly by hand, holding the finder tube close to the aforementioned parts.

After a leak has been detected, locate the exact place where it is leaking, if possible. If the leak is around the seal-plate gasket, replace the gasket. If the leak should be at the seal seat or nut, replace with a new seal plate, gasket, and seal assembly. To replace the seal, observe the following instructions:

1. Remove the compressor from the condensing unit in the usual manner.
2. Remove the flywheel, using a puller. Leave the flywheel nut on the crankshaft so that the wheel puller will not distort the threads.
3. Remove the seal guard, seal nut, and seal assembly.
4. Remove the seal plate and gasket.
5. When assembling the seal, put a small quantity of clean compressor oil on the seal face (both plate and seal).
6. Reverse these operations to reassemble. Make sure the seal plate is bolted in place and the seal guard is at the top.

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