Date: 201809
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ramp ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Time Pressure
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Equipment / Tooling; MEL; Procedure
Primary problem: Procedure

Narrative: Our aircraft had an inoperative APU. The aircraft was quite hot inside and the agents were loading a full load of passengers; so it was getting worse. While the [ground air] from the jet bridge was operating as usual it provided an inadequate supply of conditioned air. The more people boarded; the hotter it was getting. We advised Operations that we required an air start cart in order to start the engines. While waiting for the start cart one of the ramp workers shut down the jet bridge [ground air] and began pulling in the yellow hose. To communicate; it was necessary for me to open the cockpit window and yell down to him. He acknowledged the mistake and went to work re-instituting the conditioned air. Meanwhile; the passengers and flight attendants were calling complaining about how hot the aircraft had become. After a while the start cart arrived as we could hear it winding up and the aircraft packs began to provide more cold air.It was time to start the engine and begin the push. The ramp person on the headset asked me if they could pull the electrical. I reminded them that we needed that to start the engine before the push. I asked my First Officer if he had the checklist out for this start and he said he did. He thought I was talking about the cross-start checklist. As the First Officer began to turn the number 2 (left) engine he mentioned that he did not see the start cart. I told him that maybe it was close in to the aircraft and out of sight; but he replied no he could see straight down. I glanced to my left and saw the cart was way behind the safety line on the left side of the aircraft. I instructed the First Officer to discontinue the start as we had yet to add fuel. The engine wound back down.I told the ramp person on the headset that the cart had to be on the right side of the aircraft because we had to start the left engine. I even defined it as the left side as you are sitting in the cockpit. He replied that the procedure for 'this gate' was that the start cart was to be placed on the left side of the aircraft. I said 'What? Are you sure?' He replied yes. I asked how do you disconnect the hose and get it to the cart? His reply was that they disconnect it and walk it way to the front of the aircraft. My response was that did not seem right and that the engine inlets were a dangerous place to be around. His reply was that they do this all the time. I then asked again by saying 'With 737's?' He replied yes; we stay far away from the inlet. Another ramp person approached him and they had a side conversation; which I assumed to be about the cart.Meanwhile; the temperature in the aircraft continued to climb rapidly with no conditioned air coming in. He turned and looked up at me again and said that the procedure for THIS gate is that they place the start cart on the left side. I saw a ramp person with a CREW CHIEF vest standing out there by the cart. After confirming three separate times in three separate ways with the ramp personnel and seeing the Crew Chief standing there waiting at the cart I figured that there must be a special procedure for this gate (the alley gates are tight for ramp space) since the Crew Chief who worked the gate would surely know how to perform the start since they must do this a lot more than we in the cockpit do. We started the engine.After the start; I looked back to my left and saw the Crew Chief rather than bringing the hose forward was actually pulling it in to the cart directly under and perpendicular to the engine. Once in the air; and with time to spend I found the Ramp Operations Manual in my iPad and located the instructions. Clearly; we started the engine with the cart on the wrong side.What caused me to make this incorrect decision. 1. I have had 3 incidents now in ZZZ with aircraft with inoperative APU's. The first was an aircraft that was at a gate with no APU and we went through 3 separate start carts before they found one that could turn the engine sufficiently. The jet bridge was still attached and in the long delay for the ramp to find and move these carts one at a time and attempt starts; the aircraft temperature became intolerable and without ANY discussion with me the Number 1 Flight Attendant took it upon herself to deplane the passengers into the terminal. The second incident was another aircraft with inoperative APU at a gate with inoperative [ground] air. The temperature was intolerable in the plane. I refused the aircraft. Heavy on my thought process is that I realize the clock is ticking on a fully loaded aircraft without conditioned air in the summer before passengers begin to have serious issues with the heat. 2. I was busy trying to coordinate all of this and relied on the First Officer and checklist. He was looking at the next checklist we would need; not the applicable one. 3. I have always had admiration for the ramp personnel that work [this particular] alley since they have little room to operate and are required to swing the aircraft around in a pivot all the while staying on the line. I figured only experienced personnel were assigned those gates. 4. Seeing the Crew Chief actively part of this at his assigned gate led me to believing the ramp person on the headset; that there was some kind of 'special' procedure just for this gate.


Second narrative: APU was inoperative and we began air start procedure when I noticed the cart not on the right side of the aircraft. I notified the Captain who queried the crew chief. The response is that at that gate it's always done from the left side of the aircraft. We informed him that it doesn't seem correct; and there is the danger to be in such close proximity to the operating engine when removing the hose. The crew chief disagreed; and reiterated the procedure he specified. We went back and forth for a few moments; and after being reassured over and over this was the correct procedure for the gate; we accepted this info and started the left engine. We still maintain that it is the wrong procedure and the checklist concurs.We were very hot as the APU was inoperative; and the ground air was woefully inadequate. Additionally; the ground crew decided on their own to remove what little air we had and disconnected the conditioned air 10 minutes prior; without asking. I ran down and had them reconnect. This; plus the usual last few minutes chaos that accompanies getting the flight out on time perhaps brought down our guard in regards to the procedure (which we had reviewed earlier); and led us to accept the Crew Chief's word over our understanding of the proper accepted procedure.Proper training of the ground personnel; and we should've stuck to our understanding of the procedure and insisted they follow what we know to be the acceptable way to accomplish the task safely.


Synopsis: B737-800 flight crew reported that proper procedures were not being followed during an engine start using an air cart.