Auto Air Conditioning & Heater Repair: Front AC Vents, hvac system, blower motor

Question
In my 99 Yukon my AC works fine, but the air in the front ac vents does not blow very strong. Any suggestions what to check?

Answer
Hello,

  Can you determine there are all the fan speeds available?  Is there any way that the blower motor is not going on high speed?
  With your head under the dash select front vents and watch the lever on the mode door actuator.  Its the only one on the side of the HVAC box.  On the older ones there is linkage that might have come off but that would mean you would lose control of all modes so its probably ok.
 Was this something that happened right away or over a long period of time.  Sometimes debris caught in the evaporator core such as pollen or dust sticking to a film of oil of a lightly leaking evaporator core can disrupt or block air flow through the HVAC system.
 Does it blow a sufficient volume of air when the heat is on?  Is there a difference between heat and cold?

Wayne