Odd series of events--may or may not be related to each other. Last week, check engine light came on my non-turbo 2000 S70. No noticeable performance issues. Stopped at shop and had codes read; got the P0442 EVAP small leak message.

A few days later, driving home on the freeway, heard and felt a loud POP; I, and everyone else in the car, thought we'd blown a tire, that's how loud and forceful it was. Wasn't a tire, and nothing changed in the car's performance.

The next day, drove to work and things seemed fine. At lunch, noticed that the fan blower speed was acting odd; even with the blower switch set to manual max speed, the fan speed would drop precipitously when accelerating... at idle or when coasting the fan speed was at max.

Any relation between these events? If it matters, it's been hot here in Texas, pushing 100F/40C. I keep the car well maintained, and have spent over $2800 lately in shop maintenance at SW Automotive, a well-known Volvo specialist shop. Recent work includes new alternator, battery, all of the battery cables recently replaced.

I've read the threads here re: P0442, will check the purge valve and hoses; wondering if the loud bang I heard might have been something related to the filler neck, if things were pressurized. I don't see anything visible issue wise under the hood (or in the trunk--looked there to see if a can of something blew up... oh, didn't check the spare! Will check that soon and report back).

 

Found this thread that seems to link the fan speed to the vacuum issues:

https://volvoforums.com/forum/volvo-240-740-940-12/blower-fan-flow-decrease-when-i-speed-up-32416/