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No Heat

Tiny
YOLANDA69
  • MEMBER
  • 2001 LEXUS GS 300
  • 220,220 MILES
My car has not heat. My a/c works perfectly fine, my blower works perfectly fine. I just had my water pump replaced because it was leaking and my engine was over heating. I had my thermostat replaced as well. What could it be?
Wednesday, October 23rd, 2013 AT 8:44 AM

18 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Do the heater hoses get hot? Another issue could be actuator under the dash. The actuator moves one way, the air blows over the heater core and you get heat. The actuator moves the other way and the air blows over the evaporator and you get ac. This is just basic info for any vehicle.

Check out this guide I think it will help you get the problem fixed,

https://www.2carpros.com/articles/car-heater-not-working

Hvac system diagnostics,

While pressing and holding auto button and fresh/recirculated air ( air intake control) button, turn ignition on. Indicators will flash on and off at one second intervals, 4 times in succession, and a tone will sound as an indicator check. After indicator check is complete, system will enter self-diagnostic mode. Stored trouble codes will appear in sequence on driver side temperature display. Press driver side temperature switch to display codes one at a time. If a tone sounds when code is displayed, problem causing code currently exist. If the tone doesn't sound when code is displayed, the problem is part history, doesn't currently exist. Press off button to exit self-diagnostics.

Just write down the codes and post back

Please let us know what you find.

Cheers
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Wednesday, October 23rd, 2013 AT 9:05 AM
Tiny
DOUG NOYCE
  • MEMBER
  • 5 POSTS
I see this is an old post, hopefully JDL is still around.

You say "Indicators will flash on and off at one second intervals, 4 times in succession, and a tone will sound as an indicator check."

What is it exactly, that happens '4 times in succession'?

(I am still trying to figure out how to hold two buttons and starting the ignition, all of which are on the right side. I would need two right hands! Huh?) Is this direction for right side steering countries?
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Saturday, January 28th, 2017 AT 3:37 PM
Tiny
DOUG NOYCE
  • MEMBER
  • 5 POSTS
Follow-up. Did diagnostic, no tones when initiated, but codes were there after initiation. Codes were 31, 33, 41, 43, all with fan icon, and no sound. Fan works fine, just no heat=, and I guess diagnostic did not find the problem.
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Sunday, January 29th, 2017 AT 3:15 PM
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
The codes indicate an air blend door problem either a failed servo or sensor. Blend door is not moving to direct air over heater core so no heat. A series of tests must be done to determine what has failed
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Monday, January 30th, 2017 AT 1:14 PM
Tiny
DOUG NOYCE
  • MEMBER
  • 5 POSTS
What are the tests? Why did the diagnostic pick it up. From what you originally described, these codes are a history, not current problem as there was no tone sounded.
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Monday, January 30th, 2017 AT 1:20 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hey Doug,

Don't worry about the chime the temperature actuator sounds like its bad which is a common problem.

Here is a guide to help you see what you are in for with the repair and a diagram that will show you what is it on your car.

https://www.2carpros.com/articles/replace-blend-door-motor

Try to get the part from Amazon if needed.

Please let us know what happens so it will help others

Best, Ken
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Thursday, February 2nd, 2017 AT 6:24 AM
Tiny
DOUG NOYCE
  • MEMBER
  • 5 POSTS
Thanks for the install instructions. FYI, the identical part (Dorman 604917) is $117 at Amazon, and $98 at RockAuto. Com, my go-to auto parts dealer.

At any rate, I think I will try the salvage yard first, probably 75% cheaper! I will keep you posted on whether this fixes the problem. Fortunately, living in Southern Arizona, I only use the heater for a couple of days in a year, so it is not an urgent issue!
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Thursday, February 2nd, 2017 AT 9:53 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hey DOUG

Great news! Please check back when you get the problem fixed to let us know how it goes.

Best, Ken
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Thursday, February 2nd, 2017 AT 9:55 AM
Tiny
DOUG NOYCE
  • MEMBER
  • 5 POSTS
Correction: Amazon $110.30
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Thursday, February 2nd, 2017 AT 9:56 AM
Tiny
PAMLA
  • MEMBER
  • 19 POSTS
  • 1998 LEXUS GS 300
  • 112,000 MILES
At the end of summer my A/C stopped working. It was not the coolant. It was not the fuse. I have not had any diagnostic info come up when I ran a check. My compressor is working. I have coolant.

I decided to check my heater today since it is cool outside. The heater does not work either!

I am getting air out of the vents.

Any ideas on what can be wrong?
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
So you are saying the blower/fan is working?
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
PAMLA
  • MEMBER
  • 19 POSTS
The blower/fan is working. I am wondering if perhaps it is the thermostat. It may be my imagination but it seems the radiator top gets hot quickly. Is there any way to rule this out or to check for another problem?
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
You can check heater hoses going into heater core to see if they are both hot.
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
Possible AC ECU problem.
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
PAMLA
  • MEMBER
  • 19 POSTS
Hi again! Both hoses leading to the heater core are hot. I had previously run a diagnostic check in the garage. It initially showed code 21 (ECU?) And code 23. When I backed the car out into the sun, both the codes went away.
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
PAMLA
  • MEMBER
  • 19 POSTS
I took my Lexus to a small-time mechanic. He called me back to say the heater is working and that the compressor is bad on the a/c. I have trouble believing this since the clutch was working properly. Do you have any suggestions?
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
PAMLA
  • MEMBER
  • 19 POSTS
I had a friend check the pressure w/ gages. The low side is 70 to 75; the high side is 50. Therefore, the compressor is not compressing. However, the clutch is engaging, the belt is turning the compressor timely. Does this absolutely mean the compressor is bad. There are no squeals or drag on the belt. Note: I did have a mouse under my hood. Could it some wire problem? The a/c is blowing but not cool. If it is the compressor, would you recommend one from a salvage yard?
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
Those readings are funny. Will have to research more. Salvage compressor is fine if it's much reduced from new and if it is guaranteed to work.
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Thursday, December 7th, 2017 AT 8:59 PM (Merged)

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