Air Conditioning Modifications on General Motors RTS-03 Model Buses

The Southeastern Michigan Transportation Authority (SEMTA) experienced equipment problems in the General Motors Rapid Transit Series - 03 model (GM RTS-03) advanced design bus fleet. These problems resulted from engine/transmission overheats and air conditioning (A/C) condenser clogging that impacted the cooling efficiency in the bus and resulted in excessive condenser maintenance costs.

The SEMTA staff concluded that most of the equipment problems could be eliminated by relocating the A/C condenser away from the engine compartment. Stringent specifications were developed prior to competitive bidding to select a project contractor. The contractor submitted prototype equipment for the bus modification. The prototype equipment was evaluated through different testing procedures prior to the approval to modify the entire fleet of 480 buses.

The modifications included a new condenser, temperature control system, fiberglass protective housing and electric rewiring of A/C compressor clutch circuit.

Most of the bus fleet was modified during 1982 and 1983 and is performing to the satisfaction of the operating staff and passengers. SEMTA has applied for federal grants for an in-depth project evaluation.