Auto Air Conditioning & Heater Repair: Air Flow, engine vacuum, vacuum leak

Question
QUESTION: I have a 2001 Ram 1500 and it seems that every time I step on the accelerator and the air is on that is will either move from the vent to the defrost or almost stop working.. When I release from the accelerator it comes back Have NO clue why its doing that

ANSWER: Heya,

  You most definitely have a vacuum leak or defective one way valve.  When you step on the acclerator pedal the engine loses optimum vacuum and this transponds to the HVAC unit.  It is defaulting to defrost when this happens.  Do you know how to check this vacuum system?

Wayne



---------- FOLLOW-UP ----------

QUESTION: Yes it is defaulting to defrost Not to familiar with the vacuum system

Answer
Check the vacuum check valve at the right side of the intake manifold and check the second check valve in the line to the left of the receiver drier.

There is a plastic vacuum line that runs from the intake to the HVAC head through the firewall.  I am willing to bet the one way valve is defective or the line is cracked or come off the intake.  This is a VERY VERY VERY common problem.
 Follow the line from the intake to the firewall.  You will notice there are little inline valves in the line.  These are to ensure vacuum stays in the upside of the line when yhou are stepping into it.  The mode selection int he dash is dependent on engine vacuum to control the actuators and if it looses vacuum spring pressure will force them all back to default.
 If you remove this valve put it up to your mouth (after cleaning it!) and you should only be able to suck air one way.  

Wayne