(a) Prior to the official test, the test compressor selected in accordance with § 204.57-2 shall not be prepared, tested, modified, adjusted, or maintained in any manner unless such adjustments, preparations, modifications and/or tests are part of the manufacturer's prescribed manufacturing and inspection procedures and are documented in the manufacturer's internal compressor assembly and inspection procedures or unless such adjustments and/or tests are required or permitted under this subpart or are approved in advance by the Administrator. The manufacturer may perform adjustments, preparations, modifications and/or tests normally performed by a dealer to prepare the compressor for delivery to a customer or the adjustments, preparations, modifications and/or tests normally performed at the port-of-entry by the manufacturer to prepare the compressor for delivery to a dealer or customer.

(b) Equipment of fixtures necessary to conduct the test may be installed on the compressor: Provided, That such equipment of fixtures shall have no effect on the noise emissions of the compressor, as determined by the appropriate measurement methodology.

(c) In the event of compressor manfunction (i.e., failure to start, misfiring cylinder, etc.), the manufacturer may perform the maintenance necessary to enable the compressor to operate in a normal manner.

(d) No quality control, testing, assembly, or selection procedures shall be used on the completed test compressor or any portion thereof, including parts and subassemblies, that will not normally be used during the production and assembly of all other compressors of that category which will be distributed in commerce, unless such procedures are required or permitted under this subpart or are approved in advance by the Administrator.