Car overheating help!
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Driver School Candidate
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From: NY
Car overheating help!
Hello everyone! New to the forum
I just picked up my first Lexus ever! Ive owned it for about 2 weeks now 102,000 miles and it has been great but def needs some TLC. Anyway since I got the car I have been having these overheating issues. Reservoir would boil and steam. I wasn’t sure what it was until I seen this harness under the radiator (white/blue and white) completely broken. So I said to myself well that’s gotta be it. I put the wires together electrical taped it and put the negative back on started up the car and the passenger side fan would constantly run as soon as I turn the car on. I then changed the number 2 relay in the engine bay with a new one (it was missing the top part of it I guess previous owner tried to pull it out and it came out) so I just replaced the entire thing. The fan wouldn’t turn on anymore as soon as I started the car. Drove the car a little while and BAM started overheating again with the same issue. Boiling/steaming reservoir. I searched up some stuff and turned the AC on and just the passenger side fan would run in a timely manner I guess that normal. So now I came to the conclusion that when my car starts overheating the fans isnt kicking on (ac fan doesn’t with ac on or off) and the only way to keep it cool I would slap the ac on and the temp would drop back down. Any help on why my radiator fans aren't turning on, only when the AC is on?
I just picked up my first Lexus ever! Ive owned it for about 2 weeks now 102,000 miles and it has been great but def needs some TLC. Anyway since I got the car I have been having these overheating issues. Reservoir would boil and steam. I wasn’t sure what it was until I seen this harness under the radiator (white/blue and white) completely broken. So I said to myself well that’s gotta be it. I put the wires together electrical taped it and put the negative back on started up the car and the passenger side fan would constantly run as soon as I turn the car on. I then changed the number 2 relay in the engine bay with a new one (it was missing the top part of it I guess previous owner tried to pull it out and it came out) so I just replaced the entire thing. The fan wouldn’t turn on anymore as soon as I started the car. Drove the car a little while and BAM started overheating again with the same issue. Boiling/steaming reservoir. I searched up some stuff and turned the AC on and just the passenger side fan would run in a timely manner I guess that normal. So now I came to the conclusion that when my car starts overheating the fans isnt kicking on (ac fan doesn’t with ac on or off) and the only way to keep it cool I would slap the ac on and the temp would drop back down. Any help on why my radiator fans aren't turning on, only when the AC is on?
Last edited by Moorelow; Feb 16, 2018 at 09:17 AM.
Racer
Joined: Jul 2015
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From: North Carolina
Try this the next time your reservoir would "boil and steam". Turn the car off and feel upper radiator hose. Then, feel the lower radiator hose - it's a tight squeeze but your arm should fit. If one of the hoses is hot and the other is cold, it means your thermostat is probably stuck and needs to be replaced. Happened on our SC430 earlier this year.
Thread Starter
Driver School Candidate
Joined: Feb 2018
Posts: 44
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From: NY
Try this the next time your reservoir would "boil and steam". Turn the car off and feel upper radiator hose. Then, feel the lower radiator hose - it's a tight squeeze but your arm should fit. If one of the hoses is hot and the other is cold, it means your thermostat is probably stuck and needs to be replaced. Happened on our SC430 earlier this year.
thank you bro!
Thread Starter
Driver School Candidate
Joined: Feb 2018
Posts: 44
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From: NY
Try this the next time your reservoir would "boil and steam". Turn the car off and feel upper radiator hose. Then, feel the lower radiator hose - it's a tight squeeze but your arm should fit. If one of the hoses is hot and the other is cold, it means your thermostat is probably stuck and needs to be replaced. Happened on our SC430 earlier this year.
so I just tried that both bottom and top radiator hoes were somewhat soft and HOT
Sounds like your wiring harness for the fans are damaged not corrected correctly. Start the car and turn the AC on, both fans should run, if they are not that could be your problem.
Check to ensure that all the electrical wiring and connections are intact. Check the relays for the fans there are three of them.
What year/model is your car? All you do don't let the car overheat too much it could ruin your motor.
Check to ensure that all the electrical wiring and connections are intact. Check the relays for the fans there are three of them.
What year/model is your car? All you do don't let the car overheat too much it could ruin your motor.
Thread Starter
Driver School Candidate
Joined: Feb 2018
Posts: 44
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From: NY
Sounds like your wiring harness for the fans are damaged not corrected correctly. Start the car and turn the AC on, both fans should run, if they are not that could be your problem.
Check to ensure that all the electrical wiring and connections are intact. Check the relays for the fans there are three of them.
What year/model is your car? All you do don't let the car overheat too much it could ruin your motor.
Check to ensure that all the electrical wiring and connections are intact. Check the relays for the fans there are three of them.
What year/model is your car? All you do don't let the car overheat too much it could ruin your motor.
2000 GS300! When I turn the AC on only the passenger side fan runs
Last edited by Moorelow; Feb 16, 2018 at 02:33 PM.
Both fans should run when you turn on the AC or when the engine temps get too hot to cool it down. Check the fans, wiring connections and relays.
Do you have a service of the car, when last was the Timing belt, water pump changed? If not sure I suggest you get that done to ensure the cooling system is operating correctly.
Do you have a service of the car, when last was the Timing belt, water pump changed? If not sure I suggest you get that done to ensure the cooling system is operating correctly.
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Thread Starter
Driver School Candidate
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From: NY
Both fans should run when you turn on the AC or when the engine temps get too hot to cool it down. Check the fans, wiring connections and relays.
Do you have a service of the car, when last was the Timing belt, water pump changed? If not sure I suggest you get that done to ensure the cooling system is operating correctly.
Do you have a service of the car, when last was the Timing belt, water pump changed? If not sure I suggest you get that done to ensure the cooling system is operating correctly.
yeah im not sure it was a young kid that couldn’t keep up with it so I bought it from him for $500.00. I just checked the wiring and I see here that the power to that left fan is cut on the grey connector part. So that’s what it is I’m not getting power for that fan to turn on then. BUTTT that doesn’t help still the fans only operate when the AC is on. I’m thinking over the weekend then I’ll buy those other two relays and do a coolant flush then. Stupid coolant I see here is green -_-
Lexus Champion
Joined: Sep 2016
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From: AB
Do you get good heat output in the cabin? Over flow coolant means too much pressure build up. When engine is cold do a pressure test. Check the coolant state, is it proper mix?
Check thermostat, rad cap. Flush/refill rad won't hurt. Finally water pump. OP, you are in NY, still winter. Sounds like that vehicle was not very well taken care of. Good luck.
Check thermostat, rad cap. Flush/refill rad won't hurt. Finally water pump. OP, you are in NY, still winter. Sounds like that vehicle was not very well taken care of. Good luck.
Thread Starter
Driver School Candidate
Joined: Feb 2018
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From: NY
Do you get good heat output in the cabin? Over flow coolant means too much pressure build up. When engine is cold do a pressure test. Check the coolant state, is it proper mix?
Check thermostat, rad cap. Flush/refill rad won't hurt. Finally water pump. OP, you are in NY, still winter. Sounds like that vehicle was not very well taken care of. Good luck.
Check thermostat, rad cap. Flush/refill rad won't hurt. Finally water pump. OP, you are in NY, still winter. Sounds like that vehicle was not very well taken care of. Good luck.
Yeah the heat is great in the car, been using it in these cold temps here in NY. The coolant I can see needs to be flushed out it’s mixed green and red this kid was an idiot and probably just gave the car gas and kept it moving. Over the weekend I’m gonna flush that out and fill it with a proper mix. Number 1,3 relays I’ll replace along with the radiator cap. What’s the best way to check that thermo ? I’ll start looking into getting a new oem pump, timing belt, just a whole tune up!
Lexus Champion
Joined: Sep 2016
Posts: 2,047
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From: AB
Also old rad hoses are known to collapse in operation impeding coolant circulation. When you flush, you can check thermostat. There is a temp. stamped on it. Test it in boiling water.
Cap also has pressure rating stamped on it, like Rxx something like that.
Cap also has pressure rating stamped on it, like Rxx something like that.
It might be as simple as air trapped in the system. It might need to be burped. When the engine is completely cold take off the radiator cap and start the car. While the engine is running the air pockets will release. You will need to keep adding coolant/ water until it tops off.
Thread Starter
Driver School Candidate
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From: NY
It might be as simple as air trapped in the system. It might need to be burped. When the engine is completely cold take off the radiator cap and start the car. While the engine is running the air pockets will release. You will need to keep adding coolant/ water until it tops off.
with th the engine cold I started it up with the hea in full blast and the cap offt for about 15 mins. No air bubbles came out at all I always noticed is that it will build up and some of the coolant with start slowly overflowing out of the radiator.
Thread Starter
Driver School Candidate
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yeah I’m gonna flush the coolant and put a new cap and thermo this weekend and see what’s sup!
Thread Starter
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I replaced the radiator harness and now both fans are working but still only when AC is ON. I tested all relays they are good but they are all getting power. What could this be ???? Also coolant temp sensor is tested good as well