A/C and Heat not working on 1999 Mercedes-Benz E320

So my car's heat just stopped working one night. The only times that it has worked is once when i hit a huge pothole or once when i jump started a friends car, and also when it was between 50 and 70 degrees outside but even then it doesn't always work. please help! winter is too cold for a 6 month old here in mn :(

by in Hastings, MN on December 08, 2013
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2 answers 2 comments
ANSWER by , December 08, 2013
The HVAC sends .8 - 6v to the resistor mounted by the blower, whpk wire. Remove the lower hush panel to expose the blower and resistor, most of the time the blower will run at low speed not realizing it when the resistor is bad. Check voltage at whpk wire while adjusting the fan speed- .8 low to 6.0 max
ANSWER by , December 08, 2013
Is it the fan that quits running?
COMMENT by , December 08, 2013
I think so.. when I'm driving at higher speeds i can feel heat coming from the vents but it's not very much
COMMENT by , December 08, 2013
The blower motor is under the right side under dash. Try to hit the bottom of the dash on right side unless you can see the heater housing, then rap on that while the car is running with heater on. Sounds like a bad connection, or the blower motor itself is bad. It might start blowing if it is jarred, as if the big pot hole would do, but don't depend on that working every time. Have it replaced.