Intermittent AC...
Thread Starter
Pro
Joined: Jun 2003
Posts: 555
Likes: 0
From: Moline IL
Intermittent AC...
I completed a winter project on my car. I had the engine out and the AC disconnected and I also sent my digital display in for the fix to get the display working again.
I recharged my AC (new accumulator, added oil, started with a vacuum, etc.). Actually, I've done it twice from scratch (vacuum) and still have the same problem.
Sometimes the AC kicks on. Sometimes the button blinks 5 times and then shuts off. When we go on road trips, it will work about 50% of the time... we stop at a rest area, get back in, and it doesn't work again, and vice versa. Most of the time it will eventually work after driving for 10-15 minutes.
When the AC works, the vent temperature is 30-40 degrees below ambient (good per the FSM). However, the fan does not seem to blow very hard at all... on a 90 degree day it barely keeps the car cool inside, even though the vent temp is 55 degrees. I remember the fans being much stronger before.
I've replaced the high side pressure switch which showed no change in the symptoms.
No DTCs set. I can get 0530 to set if I unplug the high side pressure sensor, but no codes come up by themselves.
When monitoring with HPTuners, there is a status bit called "AC disable". The AC does not work when this bit is disabled, but I cannot figure out why sometimes it is disabled, and sometimes it is not.
When checking the pressures with the car off, AC off, engine cool, ambient temp around 70 deg, the high and low side pressures are around 75 psi.
Since the AC worked when I parked the car last winter, logic tells me the new accumulator or the "fixed" auto temp control unit are causing my issue.
Any ideas would be greatly appreciated... specifically, I am interested in what kind of problems a bad auto temp control unit can cause...
Thanks
I recharged my AC (new accumulator, added oil, started with a vacuum, etc.). Actually, I've done it twice from scratch (vacuum) and still have the same problem.
Sometimes the AC kicks on. Sometimes the button blinks 5 times and then shuts off. When we go on road trips, it will work about 50% of the time... we stop at a rest area, get back in, and it doesn't work again, and vice versa. Most of the time it will eventually work after driving for 10-15 minutes.
When the AC works, the vent temperature is 30-40 degrees below ambient (good per the FSM). However, the fan does not seem to blow very hard at all... on a 90 degree day it barely keeps the car cool inside, even though the vent temp is 55 degrees. I remember the fans being much stronger before.
I've replaced the high side pressure switch which showed no change in the symptoms.
No DTCs set. I can get 0530 to set if I unplug the high side pressure sensor, but no codes come up by themselves.
When monitoring with HPTuners, there is a status bit called "AC disable". The AC does not work when this bit is disabled, but I cannot figure out why sometimes it is disabled, and sometimes it is not.
When checking the pressures with the car off, AC off, engine cool, ambient temp around 70 deg, the high and low side pressures are around 75 psi.
Since the AC worked when I parked the car last winter, logic tells me the new accumulator or the "fixed" auto temp control unit are causing my issue.
Any ideas would be greatly appreciated... specifically, I am interested in what kind of problems a bad auto temp control unit can cause...
Thanks
Racer
Joined: Feb 2006
Posts: 295
Likes: 4
From: Riverside California
From what I have read, the norm for dual control is: No codes=low charge and codes=damper doors.
Did you replace the orifice tube also? What are the operating pressures?
The static pressures dont realy mean much other than there is some charge in there.The low fan speed puzzles me(not familiar with dual control) however if there is internal blockage such as a restricted orifice tube it can pull the low side down enough to cut off the compressor and or cause icing of the evap.which will restrict air flow and give a very humid feel to the air.
Just some thoughts to ponder,hope it helps.
Did you replace the orifice tube also? What are the operating pressures?
The static pressures dont realy mean much other than there is some charge in there.The low fan speed puzzles me(not familiar with dual control) however if there is internal blockage such as a restricted orifice tube it can pull the low side down enough to cut off the compressor and or cause icing of the evap.which will restrict air flow and give a very humid feel to the air.
Just some thoughts to ponder,hope it helps.
