Date: 201910
Local time of day: 0001-0600
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Light: Daylight
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Airspace: Class C ZZZ
Aircraft component: Aircraft Auto Temperature System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Communication Breakdown
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight; Pre-flight
Result: General Flight Cancelled / Delayed; General Maintenance Action; General Release Refused / Aircraft Not Accepted
Contributing factors: Aircraft; Human Factors; Procedure; MEL
Primary problem: Procedure

Narrative: We refused to fly XXXX based on events from inbound YYYY. We were unable to control cabins temperatures due to deferred hot air valve and both channels of zone controllers being deferred. FM says temperatures will be fixed at 20 degrees on left pack and 10 on right pack. Actual zone temps fluctuated between 48 and 100 degree for all zones during the entire flight. I discussed issue soon after ZZZ Departure with Dispatch and to [Technical Support Maintenance Control] on radio. We decided to continue and temperatures continued out of control for the rest of the flight and we almost diverted several times when cabin air temperatures approached 100. After documenting via [Maintenance Request] before YEG arrival I personally spoke to Mechanics and urged them to fix this. I woke this morning and after perusing paperwork I called [Technical Support Maintenance Control] to ascertain exactly what work was done. He said tests were run that confirmed all deferred items had faults; were already deferred and nothing else was done. XX_15 and I decided it was not safe to operate this aircraft again without these issues being fixed.We arrived at aircraft and local mechanic XX_2 was installing new zone controller. It did not fix the problem but he; [Technical Support Maintenance Control] decided to isolate a cabin air mix valve. They found by isolating the forward cabin air mix valve they could get the others to work and it was deferred. During his duties XX_2 discovered the hot air valve was not wired closed. So remember yesterday we were dispatched on YYYY to YEG under MEL XXXXX (hot air switch off; valve secured closed). Someone certified that this hot air valve was secured closed when in fact it was not. If hot air was getting past the hot air valve (because it was not secured closed) that would explain all the wild temperature variations we experienced on YYYY and we believe that it what happened.So when XX_2 finishes work [Technical Support Maintenance Control] releases the aircraft under XXXXX (hot air switch off). In reality this is the MEL we operated YYYY to YEG under because the hot air valve was not secured closed. We knew that just the hot air switch off was allowing hot air past the valve so we again refused the aircraft. I now get in a discussion with [Technical Support Maintenance Control] about releasing us under MEL XXXXX that requires the hot air valve secured shut (I now also insist that I personally visually verify the valve is indeed wired shut; which I did). My argument with [Technical Support Maintenance Control] now gets heated because I am insisting we be released under MEL XXXXX and he wants to release us XXXXX. He doesn't know that with the hot air switch off hot air is actually getting past that valve. He later admitted that he forgot about MEL XXXXX and thought XXXXX was the only option to defer that valve. Finally during this discussion he finds MEL XXXXX is an option and agreed to it. After verifying the valve is wired shut we leave and have a normal flight to ZZZ.I called [Technical Support Maintenance Control] and spoke with [Name 2]; we discussed this at length and he agreed that this is probably what happened. He was going to call ZZZ Maintenance and suggest they replace that hot air valve because it lied to us. [Name 1] also called me this morning and we smoothed things over. I apologized for my heated insistence that we apply this MEL but we agreed it was the right call.




Synopsis: A320 Captain reported refusing an aircraft that did not have MEL procedures applied properly; causing cabin temperatures to be uncontrollable.