Heater blows cold even on manual set
10-19-03, 10:37 PM
#17
Keeper of the light
iTrader: (17)
I got a paypal account, willing to place $$ on it 
i'm more sure of this than i am how to build a speedo needle. I cant remember if in or out is correct for heat, but you'll figure it out.
i'm more sure of this than i am how to build a speedo needle. I cant remember if in or out is correct for heat, but you'll figure it out.
10-20-03, 12:46 PM
#18
OLT.
I tried doing what you told me.
First I removed screw A, and removed the metal piece B which is connected to arm C.
Then I tried pushing the C into the canister D, but it wouldn't move in because there was a spring of some sort pushing C away from D. I need some advice.
I tried doing what you told me.
First I removed screw A, and removed the metal piece B which is connected to arm C.
Then I tried pushing the C into the canister D, but it wouldn't move in because there was a spring of some sort pushing C away from D. I need some advice.
10-20-03, 10:15 PM
#20
I just went through the fix a couple of weeks ago on my '93 SC400.
There are three components to that complex little doohickey ($284 from Carson Toyota, btw) - the solenoid-operated vacuum valve that gets its signal from the climate computer, the vacuum diaphragm that operates the water valve, and the water valve itself. The spring in the diaphragm keeps the valve closed. You can block the valve open with that little lever, but then the heater core will always be hot, even when you run the a/c on full cold, and the a/c won't work as well.
I don't know if it's the solenoid or the vacuum valve that fails - it's too bad they don't sell the separate components - but I spent the $284, installed it in an hour and now all is good, just in time for the monsoon season -
There are three components to that complex little doohickey ($284 from Carson Toyota, btw) - the solenoid-operated vacuum valve that gets its signal from the climate computer, the vacuum diaphragm that operates the water valve, and the water valve itself. The spring in the diaphragm keeps the valve closed. You can block the valve open with that little lever, but then the heater core will always be hot, even when you run the a/c on full cold, and the a/c won't work as well.
I don't know if it's the solenoid or the vacuum valve that fails - it's too bad they don't sell the separate components - but I spent the $284, installed it in an hour and now all is good, just in time for the monsoon season -
10-26-03, 11:26 AM
#21
Pole Position
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Well my heater problem is back also. last time i took it into Lexus and they switched the heater solonoid.
It's been 7 months ago and now its back. I checked the coolant level and it's fine. I watched the heater control valve and got a questionf for you guys/gals. I had someone turn the temp control from cool to hot slowly and watched the metal rod uder the heater control valve for movement. The rod moved instantly once he hit a certain temp range. Is this supposed to moved slowly as he turn the temp from cool to hot?
Wanted to know before i spend the money for a new heater control valve, is it broken??
It's been 7 months ago and now its back. I checked the coolant level and it's fine. I watched the heater control valve and got a questionf for you guys/gals. I had someone turn the temp control from cool to hot slowly and watched the metal rod uder the heater control valve for movement. The rod moved instantly once he hit a certain temp range. Is this supposed to moved slowly as he turn the temp from cool to hot?
Wanted to know before i spend the money for a new heater control valve, is it broken??
10-26-03, 08:37 PM
#22
The valve is either fully open or fully closed - the climate computer fine-tunes the temperature with an air mixing door, which adjusts to many positions. The point at which the water valve opens and closes is based on outside air temperature and interior temp setting. So, it sounds like your valve is working OK.
Last edited by strongsail; 10-26-03 at 08:40 PM.
11-10-04, 11:11 AM
#24
Driver School Candidate
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I know this thread is old but I figured out why my heat is not working on my SC300 from viewing this. I just wanted to add the solution that I used.
I found that that by pushing the servo arm up into the valve, the heat would start working but the arm would slowly slide back out. So I took a zip tie and put it through the linkage where the arm and servo meet up and secured the tie around the valve. Now I have heat for the winter and once summer comes, I'll cut the zip tie so that the A/C will run at full capacity.
Very happy at the no cost solution.
Let me know if there’s any bad repercussions from having the coolant run through the heater core constantly during the cold seasons.
Laters,
Rasa Partin
IMV Films
I found that that by pushing the servo arm up into the valve, the heat would start working but the arm would slowly slide back out. So I took a zip tie and put it through the linkage where the arm and servo meet up and secured the tie around the valve. Now I have heat for the winter and once summer comes, I'll cut the zip tie so that the A/C will run at full capacity.
Very happy at the no cost solution.
Let me know if there’s any bad repercussions from having the coolant run through the heater core constantly during the cold seasons.
Laters,
Rasa Partin
IMV Films
11-11-04, 11:59 AM
#25
Pole Position
Originally posted by VehicularL
I know this thread is old but I figured out why my heat is not working on my SC300 from viewing this. I just wanted to add the solution that I used.
I found that that by pushing the servo arm up into the valve, the heat would start working but the arm would slowly slide back out. So I took a zip tie and put it through the linkage where the arm and servo meet up and secured the tie around the valve. Now I have heat for the winter and once summer comes, I'll cut the zip tie so that the A/C will run at full capacity.
Very happy at the no cost solution.
Let me know if there’s any bad repercussions from having the coolant run through the heater core constantly during the cold seasons.
Laters,
Rasa Partin
IMV Films
I know this thread is old but I figured out why my heat is not working on my SC300 from viewing this. I just wanted to add the solution that I used.
I found that that by pushing the servo arm up into the valve, the heat would start working but the arm would slowly slide back out. So I took a zip tie and put it through the linkage where the arm and servo meet up and secured the tie around the valve. Now I have heat for the winter and once summer comes, I'll cut the zip tie so that the A/C will run at full capacity.
Very happy at the no cost solution.
Let me know if there’s any bad repercussions from having the coolant run through the heater core constantly during the cold seasons.
Laters,
Rasa Partin
IMV Films
CEO
11-08-05, 03:11 PM
#26
Driver School Candidate
Join Date: Nov 2005
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I also had no heat in my '92 ls400. Problem turned out to be the cable that runs from the temp servomotor to the water 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), 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$$$$.
To check cable have someone raise temp as you firmly pull cable up in the engine compartment to take up slack. Cable should go back down unassisted when you lower temp, but hesitate or not come up at all when you raise temp again. Also make sure control valve arm moves easily when detached from cable to make sure valve is not your problem.
I removed glovebox( you can detach hinges where they connect to glovebox door), lowest panel, then panel below glovebox, and some air ducts to access the servomotor area. Servomotor is located behind radio/temp units( I did not remove these but may be good alternative). Very hard to reach. Then I pulled cable off the servomotor arm and removed kink as best I could and reattached. I also sprayed cable with silicone lubricant. Don't know if this fix will last, but at least I know I don't need a new servomotor$$$$.
01-28-07, 12:04 PM
#28
Driver School Candidate
Hey I'm new just read this thread. (1994 GS300) But my problem is a little different, as in the heat takes a long time to come up to full temp. When I first turn the heater on engine temp is at its normal operating range. It takes about 30 or 40 miles until heater is heating. I just wanted to know if the problem is the heater control valve also.
09-16-09, 10:32 AM
#30
Racer
What? Did we all just lose the ability to search?
Well, there are hundreds of other "great" threads on this forum-
are you gonna bump them all, too?
https://www.clublexus.com/forums/faq...hibited_topics
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are you gonna bump them all, too?
https://www.clublexus.com/forums/faq...hibited_topics
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