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sprinkles08, ASE Certified Technician
Category: Lexus
Satisfied Customers: 23101
Experience:  ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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I have a 1998 gs400 and my drivers side blows cold but the

Customer Question

i have a 1998 gs400 and my drivers side blows cold but the passenger side blows warm. about a 15 degree difference. i noticed this on my drive back from the lexus dealership after picking up my car. they replaced my yaw rate sensor. the a/c was working on both sides when i dropped it off friday. i picked it up yesterday on monday
Submitted: 1 year ago.
Category: Lexus
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

You may have a few things going on. If it's a dual zone system then you could have a blend door or actuator issue on the side that isn't blowing the correct temperature. With dual or single, or especially if it's just a single zone system, low charge is a possibility also. If it's a single zone system then low charge is almost surely the cause.

Is it a dual or single zone system?

Customer: replied 1 year ago.
Dual zone. I had it at Lexus Friday for them to put a replacement yaw rate sensor in. The advisor said they had to take apart my dash and gear box to get to it. Could something have happened in their possession? I ask that because everything was working good before it went into the shop and the first thing I noticed was the a/c not getting cold. Then I noticed the other side blowing warm
Expert:  sprinkles08 replied 1 year ago.

I don't expect the problem is related to the work that was done.

Is it blowing warm or just a 15 degree difference? Are you able to change it to heat and have it blow normal temperature?

Customer: replied 1 year ago.
It just run warm now. I only noted the difference because I used a thermometer to measure the temperature. If I change it to heat, the heat blows on both passenger and driver side
Expert:  sprinkles08 replied 1 year ago.

If the temperature difference is only when running the a/c then there is little chance the problem is not due to low charge. The first thing that needs to be done is evacuate and recharge the system to the proper level.

Customer: replied 1 year ago.
you think it is a low charge? And after the charge, if it doesn't fix the problem or the problem reoccurs, what is next?
Expert:  sprinkles08 replied 1 year ago.

If charging it fixes the problem temporarily it's because you have a leak in the system that will need to be located and repaired.

If that does not help then you have an issue with the blend door or actuator on that side.

Customer: replied 1 year ago.
I will recharge the a/c system tomorrow and I will let you know
Expert:  sprinkles08 replied 1 year ago.


Customer: replied 1 year ago.
i recharged my a/c and it did not help. so blend door or actuator. which could it be?
Customer: replied 1 year ago.
unless you are talking about the servo motor
Expert:  sprinkles08 replied 1 year ago.

What were the high and low side pressures after charging and what was the ambient temperature?

Customer: replied 1 year ago.
The temperature was around 80. High was about 190. Low was 45
Expert:  sprinkles08 replied 1 year ago.

You're testing vent temperature at the left and right vents in the center of the dash and there is a 15 degree difference?

Customer: replied 1 year ago.
I tested the middle two vents in the center. Also, the driver door side and well as passenger door side.
Expert:  sprinkles08 replied 1 year ago.

You're not far off from normal but if you want to pursue it then the blend door and actuator would need to be investigated. Up to 12 degrees difference at the center vents is considered acceptable.

Customer: replied 1 year ago.
how is 12 degrees in the center console considered acceptable? then what is considered acceptable between the vent on the passenger and driver side door? 20 degrees? you just said up to 12 degrees is acceptable but i told you it was 15. if the low and high are close to normal how can it still be 15 degrees difference in temp. i still cant wrap my head that 12 degree is considered acceptable. i took it to my friends shop today, he told me general rule of ac is that it should be at least 15-20 degrees below what your low point is on the ac. as far as 12 degrees difference being "normal" after a recharge, i will call and ask tomorrow.
Expert:  sprinkles08 replied 1 year ago.

There isn't a specification for outer vents, temperature is measured at the center.

Regardless, it's up to you whether you want to pursue the issue or not. If the system is fully charged and operating correctly and you're not ok with the slight temperature difference then it's going to require dash removal.