Non-uniform cooling from vents
07-28-05, 06:23 PM
#1
Intermediate
Thread Starter
Non-uniform cooling from vents
My 1990 LS400 has non-uniform cooling at the front vents.
Ever since I bought the car about a month ago, both the driver's side vents do not seem as cool as the passenger side vents. Even with the AC running for over an hour, the driver's side vents will become cool at most, while the passenger side vents are ice cold. That leads me to believe that the AC system is working properly. (This was the same before and after replacing my AC compressor, for those who have been following my other post.)
If I close the middle passenger side vent, then the cold air finally reaches the driver's side vents. But as long as it's open, the driver's side vent will not get as cold as the passenger side.
Does anybody have any thoughts?
Ramble: Since there are two filters in the glovebox, does that mean the driver's side and passenger's side vents are separate systems? Or am I thinking nonsense?
Ever since I bought the car about a month ago, both the driver's side vents do not seem as cool as the passenger side vents. Even with the AC running for over an hour, the driver's side vents will become cool at most, while the passenger side vents are ice cold. That leads me to believe that the AC system is working properly. (This was the same before and after replacing my AC compressor, for those who have been following my other post.)
If I close the middle passenger side vent, then the cold air finally reaches the driver's side vents. But as long as it's open, the driver's side vent will not get as cold as the passenger side.
Does anybody have any thoughts?
Ramble: Since there are two filters in the glovebox, does that mean the driver's side and passenger's side vents are separate systems? Or am I thinking nonsense?
08-01-05, 01:14 AM
#2
Intermediate
Thread Starter
Anybody?
Some more symptoms:
1) AC diagnostic checks out to Code 00, which is the code for Normal
2) the servo diagnostic mode checks out okay
3) when set to any other mode than Vent (like Vent-Floor) all the different vents blow the same temperature air
I did some thinking and narrowed it down some more:
1) I don't think I have the AC system filters (does anybody know how to get to them or know how to see if I have the filters?)
2) on my previous freon charge before my compressor died, my vents were uniformly cool
3) I thought the water valve for the heater core was stuck open, but it's not (I tested it)
Can a low freon charge cause the un-uniform air temperature?
Some more symptoms:
1) AC diagnostic checks out to Code 00, which is the code for Normal
2) the servo diagnostic mode checks out okay
3) when set to any other mode than Vent (like Vent-Floor) all the different vents blow the same temperature air
I did some thinking and narrowed it down some more:
1) I don't think I have the AC system filters (does anybody know how to get to them or know how to see if I have the filters?)
2) on my previous freon charge before my compressor died, my vents were uniformly cool
3) I thought the water valve for the heater core was stuck open, but it's not (I tested it)
Can a low freon charge cause the un-uniform air temperature?
08-01-05, 04:21 PM
#4
This is one area that technology can get mucked up. In the old days, the venting was controlled by wire. With vacuum assist, blend doors can open part or not at all. Checking for vacuum leaks under/in the dash. 
On my MX73 Cressida the main climate control vacuum switch was in the engine compartmet. a simple bump after 10 years would free the line and that made the difference from A/C and none at all. On this vintage of Lexus, there may be many hoses to check.
On my MX73 Cressida the main climate control vacuum switch was in the engine compartmet. a simple bump after 10 years would free the line and that made the difference from A/C and none at all. On this vintage of Lexus, there may be many hoses to check.
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LouLee
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