98 Volvo S70. My heater fan only blows occasionally. When breaking or accelerating or when I hit a bump in the road. Could it just be a connection is not tight? I recently had the heater core unit replaced about 5 months ago and it has worked fine until it got 10 degrees here. PLEASE HELP....I'M FREEZING!!!

SOURCE: volvo s70 radio code

You must take the car to a Volvo dealer so they can reference the code from the VIN number. If you call it in, they only assume you stole the radio. Sometimes you have to prove you own the car.

SOURCE: 98 volvo s70 stalling out, then finally after a day wouldnt start

If the air pump system is setting a fault, then the check valve is probably bad. If it is not addressed, eventually exhaust gases can run back through the air hose to the air filter housing and destroy the MAF sensor, causing these types of problems.

The fuel pump also fails and is a more likely cause of the stalling, and it wont set a code.

SOURCE: Replace Heater Core for Volvo S70 (1999)

It is your heater core. I fixed mine for $144. Ordered the new part on Ebay and followed these instructions http://www.volvospeed.com/vs_forum/index.php?showtopic=9717 It was very simple, I'm a middle age grandmother! The hardest part was cleaning up all the antifreeze. You will need a shopvac, a small one is $20 at WalMart.

SOURCE: The windows fog up inside of my Volvo S70

Sure sounds like the heater core, the only other thing would be some time of leak that is raising the moisture in the car is the floor board on the passengers side wet? If not look toward the heater core.

SOURCE: volvo s70 heater core

FIRST OF ALL YOU NEED A HAYNES OR CHILTON REPAIR MANUAL.IT WILL TELL YOU HOW TO GET TO HEATER CORE.AND YOU NEED TOOL NO.155 8957 DISCONNECT THE HEATER HOSES FROM HEATER CORE.AND YOU NEED A TORX 20 SCREW DRIVER TO REMOVE SOUND PROOFING PANEL TO DASHBOARD SCREWS.