Narrative:

Climbing through the upper 20's I turned on the WX radar in preparation for thunderstorm avoidance ahead on our route. The WX display annunciation was displayed and soon associated with an equipment cooling problem. The equipment cooling supply off light subsequently illuminated. I instructed the first officer to run the irregular procedure for the equipment cooling. While he was looking that up in the flight manual the cabin altitude horn sounded. The cabin was verified to be climbing above 10000 ft at a rate just over 500 FPM and the outflow showed full closed. We immediately donned oxygen and established communications. The checklist for cabin altitude warning was then performed. Having 2 problems at once was disconcerting. Out of concern that we had a more serious yet unidented problem, while the first officer worked on regaining control of the pressurization, I told ATC of our situation and requested an immediate descent. ATC cleared us to FL180 and asked if I was declaring an emergency. To allow time to run the procedure I told him to stand by and I'd tell him shortly. Passing through the mid 20's the cabin rate reversed, so I advised ATC that we did not need to declare an emergency. We descended to 10000 ft and held in the vicinity of dfw, checked on the status of the cabin, consulted with dispatch and maintenance. During this, our jump seater, an air traffic controller, indicated that he had heard a crackling noise originating behind the first officer's circuit breaker panel just as events began. Based on this report and compound problems it was decided a landing at dfw was prudent. The cabin altitude did not exceed 14000 ft during this event and passenger oxygen was not deployed. No problem was found that was common to both malfunctions. The equipment cooling fan was deferred, a new pressure controller installed, and the flight dispatched without further event.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737 CREW LOST CTL OF CABIN PRESSURIZATION DURING CLB.

Narrative: CLBING THROUGH THE UPPER 20'S I TURNED ON THE WX RADAR IN PREPARATION FOR TSTM AVOIDANCE AHEAD ON OUR RTE. THE WX DISPLAY ANNUNCIATION WAS DISPLAYED AND SOON ASSOCIATED WITH AN EQUIP COOLING PROB. THE EQUIP COOLING SUPPLY OFF LIGHT SUBSEQUENTLY ILLUMINATED. I INSTRUCTED THE FO TO RUN THE IRREGULAR PROC FOR THE EQUIP COOLING. WHILE HE WAS LOOKING THAT UP IN THE FLT MANUAL THE CABIN ALT HORN SOUNDED. THE CABIN WAS VERIFIED TO BE CLBING ABOVE 10000 FT AT A RATE JUST OVER 500 FPM AND THE OUTFLOW SHOWED FULL CLOSED. WE IMMEDIATELY DONNED OXYGEN AND ESTABLISHED COMS. THE CHKLIST FOR CABIN ALT WARNING WAS THEN PERFORMED. HAVING 2 PROBS AT ONCE WAS DISCONCERTING. OUT OF CONCERN THAT WE HAD A MORE SERIOUS YET UNIDENTED PROB, WHILE THE FO WORKED ON REGAINING CTL OF THE PRESSURIZATION, I TOLD ATC OF OUR SIT AND REQUESTED AN IMMEDIATE DSCNT. ATC CLRED US TO FL180 AND ASKED IF I WAS DECLARING AN EMER. TO ALLOW TIME TO RUN THE PROC I TOLD HIM TO STAND BY AND I'D TELL HIM SHORTLY. PASSING THROUGH THE MID 20'S THE CABIN RATE REVERSED, SO I ADVISED ATC THAT WE DID NOT NEED TO DECLARE AN EMER. WE DSNDED TO 10000 FT AND HELD IN THE VICINITY OF DFW, CHKED ON THE STATUS OF THE CABIN, CONSULTED WITH DISPATCH AND MAINT. DURING THIS, OUR JUMP SEATER, AN AIR TFC CTLR, INDICATED THAT HE HAD HEARD A CRACKLING NOISE ORIGINATING BEHIND THE FO'S CIRCUIT BREAKER PANEL JUST AS EVENTS BEGAN. BASED ON THIS RPT AND COMPOUND PROBS IT WAS DECIDED A LNDG AT DFW WAS PRUDENT. THE CABIN ALT DID NOT EXCEED 14000 FT DURING THIS EVENT AND PAX OXYGEN WAS NOT DEPLOYED. NO PROB WAS FOUND THAT WAS COMMON TO BOTH MALFUNCTIONS. THE EQUIP COOLING FAN WAS DEFERRED, A NEW PRESSURE CTLR INSTALLED, AND THE FLT DISPATCHED WITHOUT FURTHER EVENT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.