2011 Range HVAc air flow issue.

lforgue8

Well-known member
Jul 23, 2006
1,210
0
MA
This is an odd one for sure. 2011 full size range 139,000 miles. My personal truck. After a long drive the A/C HVAC airflow stops coming out of vents but you can still feel the cool a/c air slightly. No faults get stored when checking with SDD and if the vehicle is left to "shut down" for an hour or so its back to normal. No amount of fiddling with the controls cures it when it's happening. Because of the odd nature of this I'm leaning towards a HVAC module but I wanted to now if anyone has run across this, as in my shop this hasn't been seen before.

well thanks ahead of time!
 

discostew

Well-known member
Sep 14, 2010
7,275
837
Northern Illinois
Does your blowwer fan work well on all speeds? Those had an issue where the evap would completely freeze over and cause what your dealing with. So it's a sililar problem to when your house HVAC system freezes up because the filter is restricted. So either a low charge causing the evap core to freeze up, or some other reason your having poor airflow.
 

lforgue8

Well-known member
Jul 23, 2006
1,210
0
MA
Does your blowwer fan work well on all speeds? Those had an issue where the evap would completely freeze over and cause what your dealing with. So it's a sililar problem to when your house HVAC system freezes up because the filter is restricted. So either a low charge causing the evap core to freeze up, or some other reason your having poor airflow.
yea the blower does still work. its really odd, refrigerant amount is where it should be and compressor pressures are normal. I cant get the ac machine on the car while its happening though so it would be great if I could see what the pressures are doing when its happening but I just have a gut feeling its the module.
 

discostew

Well-known member
Sep 14, 2010
7,275
837
Northern Illinois
Are you talking about the blower control module? I think it could also be the compressor. Those things are strange too. But you should try to see what the pressures are doing when it happens. Pull them up on a scan tool and wait for it to happen. I know you can watch the high side at least. Also evap temp would be relevant I suppose.
 

lforgue8

Well-known member
Jul 23, 2006
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0
MA
I've done plenty of blowers and resistors so no not that.......on the 10-12 the controls/dials is also the HVAC module. I was hoping someone may have had a similar issue and came to the same conclusion. I could have SDD running and drive it around and hope to catch something but its so intermittent. and it happens right when you need the AC....on the highway in the summer with the whole family in the car!
 

discostew

Well-known member
Sep 14, 2010
7,275
837
Northern Illinois
I've replaced a few of those. One time it was keeping the coolant flow control valve open. So it was running hot air thru th heater core on one side causing shitty cooling on one side.
So your saying you hear the blower and it's blowing full tilt but no air is coming out of the vents? If thats the case I bet the evap is a big chunk of ice. I've seen one or 2 cars where the a/c line is coming apart inside and causing a big restriction. But that wasn't intermittent.