Heater problem on a 99 LS400

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Oct 12, 2005 | 09:49 PM

afaleti

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Driver

Joined: Jul 2004

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From: Maryland

Heater problem on a 99 LS400

I have a 99LS whose heater blows cool/warm air even after I set the thermostat to very high temperatures between 78-82 Degrees.

Has anyone had the same issue before?

Does anyone have an idea if this is easy to fix ?

I hope it is a matter of just replacing the thermostert !

Thanks

Oct 13, 2005 | 02:36 AM

GRAND_LS 4

3UZ-FEEEE

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From: Northern VA

is this by any chance when you first start the car in the morning?

Oct 13, 2005 | 05:22 AM

afaleti

Thread Starter

Driver

Joined: Jul 2004

Posts: 138

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From: Maryland

Quote:

Originally Posted by GRAND_LS 4

is this by any chance when you first start the car in the morning?

Nope, even after driving for almost 30 minutes ... my 94GS never did that

Thanks

Oct 13, 2005 | 01:29 PM

GRAND_LS 4

3UZ-FEEEE

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From: Northern VA

is your coolent up topped off? Does your Temp gauge center after 10mins of driving?
Not sure what the problem is, but we can take it a step at a time.

Oct 14, 2005 | 06:52 AM

JDMUSCLE

Lexus Test Driver

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From: TX

hey man, the reason you are experiencing the heat is because of the lack of pressure in your engine cooling system which circulates in the heater core in the dash.

check and see if you have enough coolant, if not then you know its escaping out some how and if the thermostat is bad or stuck open the engine wont reach proper driving temps fast enough or will over heat under stress. hope i helped

-yogesh

Oct 14, 2005 | 12:44 PM

ToyLexmods

Lead Lap

Joined: Nov 2001

Posts: 402

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From: Arizona

Quote:

Originally Posted by afaleti

Well, lets look at some possible causes...

*Heater control valve stuck or not opening letting hot water in the heater core.
*Heater core plugged
*Low coolant level
*Engine coolant temps not getting hot...ie thermostat stuck open
Those are the easy checks.

Electronics.....well, not easy so lets get the above checked first.

Good luck

Oct 17, 2005 | 08:02 AM

Maddskillz

Driver School Candidate

Joined: Aug 2005

Posts: 4

Likes: 0

From: ga

I have the same problems with my 93 right now! With the exception that my car has overheated in traffic, then magically the temp came back down to where it was supposed to be. I am going to get it checked out today, I will let you know what my mechanic says...

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Nov 8, 2005 | 03:06 PM

silcos

Driver School Candidate

Joined: Nov 2005

Posts: 3

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From: nj

I also had no heat in my '92 ls400. Problem turned out to be the cable that runs from the temp servomotor to the heater control valve in the engine compartment at the firewall.
Over the years the cable had developed a kink at the end that attaches to the servomotor arm that caused the cable to twist and bend outside the sleeve instead of moving freely through the sleeve.

To check cable have someone raise temp as you firmly pull cable up in the engine compartment to take up slack. Cable should go back down unassisted when you lower temp, but hesitate or not come up at all when you raise temp again. Also make sure control valve arm moves easily when detached from cable to make sure valve is not your problem.

I removed glovebox( you can detach hinges where they connect to glovebox door, door stays attached), lowest panel, then panel below glovebox, and some air ducts to access the servomotor area. Servomotor is located behind radio/temp units( I did not remove these but may be good alternative). Very hard to reach. Then I pulled cable off the servomotor arm and removed kink as best I could and reattached. I also sprayed cable with silicone lubricant. Don't know if this fix will last, but at least I know I don't need a new servomotor$$$$.