Do I have the Blend Door Problem ?

[RonD]

My Truck is a 2005 3500, with the dual zone HVAC. The pass side on AC is 59 degrees with a thermometer in the dash vent, the drivers side is 45 degrees, so something is going on. The real issue that stumps me is when you start the engine the first time of the day after about 20 seconds there is a loud bang coming from the floor area under the dash, if the AC is off it won't do it, but when you turn od the AC it happens. Do I have a sticking door that slams closed or something?, thanks Ron

 

[Bob4x4]

The temp difference is usually just an undercharge condition. Verify charge level first. The noise you are hearing maybe the compressor engaging.



Bob

 

[RonD]

I had the charge looked at, it's normal, the noise happens when the AC is turned on, it isn't the compressor, it sounds like a bang coming from the floor under the dash, it's very loud, something is slamming against something.

 

[Bob4x4]

In that case you can check it with the drb for DTC's. It will catch any electrical fault but not a broken door. It sucks if you tear it down first and see nothing physically wrong.



Bob

 

[Hincka]

I have the same thing happening. It seems to only happen when the AC compressor is engaged. I have the defrost on and it will clunk hard every so often while driving down the road, when i swtich it to floor it will not make the noise again, until I switch it back to defrost.