Clearly, the contract in question is one for a piece of work. It is not petitioner's line of business to manufacture air-conditioning systems to be sold "off-the-shelf." Its business and particular field of expertise is the fabrication and installation of such systems as ordered by customers and in accordance with the particular plans and specifications provided by the customers. Naturally, the price or compensation for the system manufactured and installed will depend greatly on the particular plans and specifications agreed upon with the customers.

The obligations of a contractor for a piece of work are set forth in Articles 1714 and 1715 of the Civil Code, which provide:

Art. 1714. If the contractor agrees to produce the work from material furnished by him, he shall deliver the thing produced to the employer and transfer dominion over the thing. This contract shall be governed by the following articles as well as by the pertinent provisions on warranty of title and against hidden defects and the payment of price in a contract of sale.

Art. 1715. The contractor shall execute the work in such a manner that it has the qualities agreed upon and has no defects which destroy or lessen its value or fitness for its ordinary or stipulated use. Should the work be not of such quality, the employer may require that the contractor remove the defect or execute another work. If the contractor fails or refuses to comply with this obligation, the employer may have the defect removed or another work executed, at the contractor's cost.

The provisions on warranty against hidden defects, referred to in Art. 1714 above-quoted, are found in Articles 1561 and 1566, which read as follows:

Art. 1561. The vendor shall be responsible for warranty against the hidden defects which the thing sold may have, should they render it unfit for the use for which it is intended, or should they diminish its fitness for such use to such an extent that, had the vendee been aware thereof, he would not have acquired it or would have given a lower price for it; but said vendor shall not be answerable for patent defects or those which may be visible, or for those which are not visible if the vendee is an expert who, by reason of his trade or profession, should have known them.

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Art. 1566. The vendor is responsible to the vendee for any hidden faults or defects in the thing sold, even though he was not aware thereof.

This provision shall not apply if the contrary has been stipulated, and the vendor was not aware of the hidden faults or defects in the thing sold.

The remedy against violations of the warranty against hidden defects is either to withdraw from the contract (redhibitory action) or to demand a proportionate reduction of the price (accion quanti manoris), with damages in either case¹⁴ .