Monday, December 26, 2011

HVAC system blows hot/cold to dash and floor, but just does not blow through the defrost vents?

2003 Dodge Ram 1500 quad cab.

While replacing a leaking heater core (since the dash was removed anyway), a local mechanic attempted to correct a 2-year-old problem with my defrost: the selector switch does not direct air to the defrost vents. The system blows strong and hot/cold to dash and floor, but just does not blow through the defrost vents. He replaced/repaired the blend doors/housing/selector motor assemblies (blend door hinge pins and/or pin housing were broken/cracked). It seemed to work at least once after the repair. But after running through the selections on the HVAC switch (floor, dash, defrost) a couple of times, it again failed to blow to the defrost. During the second attempt to repair it, he first verified that the fixed/replaced blend door unit repairs/replacements had not broken again (they were still OK). He did realign/reattach the blend motor drive motors and reassembled the dash. I picked it up the 2nd time and had the same results...ran through the various settings a few times, got the defrost two blow once/twice, but soon the defrost failed to blow to the dash again.

At last the

Heater/blower switch was replaced and all is fine again.The problem solved after replacing the switch.Also the hose was pinched a bit.


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