By Patricia De Leon | CNN Philippines | June 04, 2015

Frustrated passengers walked out of the North Avenue station on Tuesday (June 2) when the first trip at 4:30 a.m. was delayed by half an hour.

More than 13,000 commuters were inconvenienced with only nine trains running as three trains had to be pulled out for repairs due to problems in the air-conditioning units.

MRT general manager Roman Buenafe said 15 to 17 trains can be deployed everyday but most trains do not have proper air-conditioning.

Maintenance provider Autre Porte Technique Global Inc. (APT Global) said the air-conditioning system, which is now 15 years old, should have been overhauled seven years ago.

Compressors were delivered in February but these were used to replace defective ones. New ones are yet to be delivered.

In a letter to MRT authorities, it suggested increasing temperatures from 20°C to 28°C to lessen the strain on the cooling system.

It also recommended lessening the number of passengers per coach to 274, as specified in the contract, citing overcrowding coupled with the hot temperatures outside as factors behind air-conditioning break down.

But solving air-conditioning problems at the expense of passengers is not a good idea, according to Buenafe.

He said MRT woes could be resolved once a new maintenance provider is assigned. This report aired on CNN Philippines' Network News on June 2, 2015.