MEDO

Some times when I drive for Half an hour, then stop for a while , I need to turn off. then return to turn on. Its also need to about 5 or 6 minutes to warm up? in spite of the temp. gauge is points to normal warm engine!!

LS400 -1990 ... The main problem is: when I restart the engine again (Turn off - then after 20 seconds turn on). I need waiting about 5 minutes again to reach 800 RPM from about 1400 ? Is that normal? The temprature gauge is points to warm machine. i.e. its not cold) Please advise me

I have a problem in my Lexus 400 model 1990 .. When I start up the engine, speed is high ( up to 1400 ) and then begin gradually decreased up to 850 .. .. And when I drive, suddenly increase in engine speed .. watch RPM meter when stopped at the traffic light .. When Keep Gear on the D and kept down break pedal .. I notice that the speed of rotation of the engine at 1100 .. with loud voice of the engine .. the air conditioner is turned off .. My question is: What are the sensors that can affect the speed of rotation of the engine .. Too much? Does the air temperature sensors within the Mass Air Flow has effect on the speed of rotation? Is the TPS has effect? Note that I examined the electronic signals the error .. Does not have any error code. Cleaned the throttle body .. with no benefit. The main problem is: when I restart the engine again (through 20 seconds), I need to wait about 5 minutes again to reach 800 RPM from about 1400 ? Is that normal? Please advise me

Thank you very much .. It's exactly like the one in the first web site .. I will try to check all the pieces, as in the illustration .. I think it's very useful. Thanks again for the advice.

Dear billydpowell.. I checked the valve as in the photo, I can't find it .. I think its lifted or may be the system is differs (you know I was talk about LS400 model 1990) .. Thanks a lot for your >> Please advice, is the blower-fan of heater differs than the cooler?

In fact, I did not feel any stream of the air .. Lighting only operates in the keys .. But does not have a hot air .. When the press directed toward the face begins air duct, but cool .. I mean that there is a flow of cold air only .. When the press raise the temperature to the highest limit stops airflow completely.

Indeed, NO .. When AC off and temp. set to MAX I did not get hot air blowing ? Is that normal ?

My language is not English .. When I run the air-conditioning .. I get only cold air .. Even when the press raise the temperature? Can you explain how the air conditioning turned up for the purpose of heating .. And not for the purpose of cooling? Is there a particular button transferred from the cooling to heating? Press the "Auto" button to get the HVAC system into automatic mode. Then select your desired cabin temperature with the up/down button. The AC (air conditioning) compressor will come on in Defrost mode(to dehumidify the air) even when calling for heat. But normally, you do not want the AC turned on when you desire heat. The Auto mode will select the proper system components to give you the desired temperature. Thanks a lot Landar ... I will try it

My language is not English .. When I run the air-conditioning .. I get only cold air .. Even when the press raise the temperature? Can you explain how the air conditioning turned up for the purpose of heating .. And not for the purpose of cooling? Is there a particular button transferred from the cooling to heating?

Indeed, I was have the same problem (slow warm up) .. I tried to put piece of cardboard in front of radiator to minimize air quantity blowing by main mechanical fan .. Also I checked the Thermostat, by put it in a boiling water, (its opened with no problem..and its closed when put it in cold water). But I observed a very small piece of the rubber ring is broken, and when Thermostat closed at cold state, its remaining to leaks some water through the closed gate, just I removed all that rubber ring and that makes the gate closing completely .. Then I return it back in its hose .. Its work ... Now I need about 6 minutes only to warm up to the normal state and return the RPM to 800 from 1400. Can you explain exactly I didn't really understand what you are saying. That there was leaks and fluid was still going to the engine? Which rubber ring are you talking , is there rubber on the actual thermostat or are you talking about the thermostat gasket or something else completely, please let me know! Well, during test the thermostat by lifting from the place and put it in a basin of boiling water then in cold water, and when the gate is closed, I noticed water leaking from the gate because of damage gasket surrounding the holding of which does not allow rubber clasps tightly to the gate .. Means that even in the case of closure of thermostat, still leaking water from it .. so, this car does not heat up because of the continuation of water circulation. So, you need to checkup the thermostat and the temperature sensor

Hi.. When I turn on A/C, I get only COLD air ?? How can I make it HOT ? Please , what is the procedure to turn on the seat heater? Is it available in Lexus LS400 1990 (First Generation)?

Indeed, I was have the same problem (slow warm up) Need more than 20 minutes .. I tried to put piece of cardboard in front of radiator to minimize air quantity blowing by main mechanical fan .. Also I checked the Thermostat, by put it in a boiling water, (its opened with no problem..and its closed when put it in cold water). But I observed a very small piece of the rubber ring is broken, and when Thermostat closed at cold state, its remaining to leaks some water through the closed gate, just I removed all that rubber ring and that makes the gate closing completely .. Then I return it back in its hose .. Its work ... Now I need about 6 minutes only to warm up to the normal state and return the RPM to 800 from 1400.

Indeed, I was have the same problem (slow warm up) .. I tried to put piece of cardboard in front of radiator to minimize air quantity blowing by main mechanical fan .. Also I checked the Thermostat, by put it in a boiling water, (its opened with no problem..and its closed when put it in cold water). But I observed a very small piece of the rubber ring is broken, and when Thermostat closed at cold state, its remaining to leaks some water through the closed gate, just I removed all that rubber ring and that makes the gate closing completely .. Then I return it back in its hose .. Its work ... Now I need about 6 minutes only to warm up to the normal state and return the RPM to 800 from 1400.

Do you replaced the ECT ? Is that affect on the warming-up time and fuel consumption? Please post, I have the same problem.

Dears My Lexus LS400-1990 is very slow warming-up. The cooling fan is start immediately with starting engine. And fuel consumption is abnormal (too much). Also the RPM is about 1600 until warming. Is that normal? What is the reason?