AC blows warm only at red light
#1
Driver School Candidate
Thread Starter
AC blows warm only at red light
The AC in my 02 ES blows nice and cold, as long as I am moving! Once I stop at a red light, warm(er) air begins to blow. Light turns green.....cold again...
I have had a few mechanics look at this, and it seems that everyone has a different idea. One says that 1 of the 2 fans near the radiator stops, so the air turns warm. Another says, no, that's normal, one fan is for AC and the other to cool the radiator...
Another said that it is the level of RS32a in the system...the other than says no, it cannot be that, since it does blow cold when moving.
Yet another mechanic did a check on all of the fuses and relays (which were all apparently working, and said, it must be the compressor.....
Feel like I am playing Russian Roulette on the diagnosis.....and certainly do not want to throw $$ at it trying everything possible...
Has anyone else had this particular experience, or might know exactly what might be causing this?
I have had a few mechanics look at this, and it seems that everyone has a different idea. One says that 1 of the 2 fans near the radiator stops, so the air turns warm. Another says, no, that's normal, one fan is for AC and the other to cool the radiator...
Another said that it is the level of RS32a in the system...the other than says no, it cannot be that, since it does blow cold when moving.
Yet another mechanic did a check on all of the fuses and relays (which were all apparently working, and said, it must be the compressor.....
Feel like I am playing Russian Roulette on the diagnosis.....and certainly do not want to throw $$ at it trying everything possible...
Has anyone else had this particular experience, or might know exactly what might be causing this?
#2
Lexus Fanatic
Someone with a 2002+ ES can confirm, I believe both fans should run when the A/C compressor is on so check for that. A competent shop with proper equipment can easily check the refrigerant level/charge.
#3
Driver School Candidate
Thread Starter
Refrigerant level is good, I have already had that checked. So......if (and that's a big if) BOTH fans should run......what is causing the fan on the passenger side to stop running whenever the car is at a light?
#4
It's a long shot but voltage drops when you are idling due to low rpms. I'm pretty sure both fans should be running when the ac is on, they do on my 99. Maybe the fan isn't running due low voltage output from the battery/alternator and that's causing the ac to blow warm.
easy way to test this is have someone look at the fans while you are in park and give the car gas, they can measure the voltage before and after and/or look at the fans to see if they both run. You can also see if the ac starts to blow colder if you give the car a little gas while in park.
easy way to test this is have someone look at the fans while you are in park and give the car gas, they can measure the voltage before and after and/or look at the fans to see if they both run. You can also see if the ac starts to blow colder if you give the car a little gas while in park.
#5
Pole Position
Do you get a blinking climate control light and have you replaced the a/c relay in the engine fuse box with the updated unit? The OE cc relay in the 02+ models is known to fail and has been updated.
#6
Driver School Candidate
Thread Starter
CRWYS - Yes!! Both fans will start when I give it a little gas and it blows cold!!
ORO - I did replace a relay last year....was hoping that it would fix the issue. Is it possible that I replaced it with a new unit but the old version? How can I distinguish? Is there a different part# for the new version? Does anyone know what it is??
ORO - I did replace a relay last year....was hoping that it would fix the issue. Is it possible that I replaced it with a new unit but the old version? How can I distinguish? Is there a different part# for the new version? Does anyone know what it is??
#7
CRWYS - Yes!! Both fans will start when I give it a little gas and it blows cold!!
ORO - I did replace a relay last year....was hoping that it would fix the issue. Is it possible that I replaced it with a new but old model? Is there a different part# for the new version? Does anyone know what it is??
ORO - I did replace a relay last year....was hoping that it would fix the issue. Is it possible that I replaced it with a new but old model? Is there a different part# for the new version? Does anyone know what it is??
If its not too low or you aren't noticing any dimming headlights or anything like that I wouldn't think it's your alternator, maybe also check the voltage on the fan plug that isn't running.
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#9
Pole Position
If you replaced the relay it is likely the new unit. You can google/search this to see the p/n difference.
Like crwys says, take the voltmeter and check alternator output. You may have a strong battery and weak alt. If you have a 2002, it is about time for that to fail. Check charging voltage across battery terminals is a good way; anything less than 14 at idle is a fail. Really 14.2, but I am being generous. A good alt will be between 14.4 and 14.6 at ALL enginve revs.
Like crwys says, take the voltmeter and check alternator output. You may have a strong battery and weak alt. If you have a 2002, it is about time for that to fail. Check charging voltage across battery terminals is a good way; anything less than 14 at idle is a fail. Really 14.2, but I am being generous. A good alt will be between 14.4 and 14.6 at ALL enginve revs.
#10
https://www.autobatteries.com/en-us/...ge-and-testing
I would also test the voltage on the connector that plugs into the fan that you have having trouble with. There is 2 terminals on the inside of the plug, you just touch the 2 while the car is running with the A/C. Same for when you test your voltage on your battery/alternator.
If your voltage is good on both your Battery/alternator and fan connector I would look into testing your fan motor and/or replacing it.
Last edited by crwys; 06-08-18 at 10:22 AM.
#11
Driver School Candidate
Thread Starter
All GREAT advice.....will look into this and let you guys know. In the meantime if anyone else has any additional information, please feel free to chime in!!!
Great forum!!
Great forum!!
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