Heater problem finally solved (two years!) (3 Viewers)

[jdotlim]

Here are notes from my receipt “Checked engine temp with scanner (190 F). Suspect heater core issue. Flushed out core, let sit overnight with C.L.R. Flushed today and heat is extremely hot (143.5 F) at center vent. Foot setting is never as hot as center vent due to design, but hot there also.“ $100.00.

best $100.00 I have spent on this rig to date.

Flushed the core and still nothing. I’m out of luck. I can hear and see the motor when I change the temp.

 

[ClassyJalopy]

Flushed the core and still nothing. I’m out of luck. I can hear and see the motor when I change the temp.

Two thoughts:
1) is your thermostat working? If thermostat is stuck open your engine won't get a chance to get to the operating temps and the coolant won't get hot enough to effectively provide heats. The heat gauge in the dash ahould be in the middle when engine warms up

2) Once the engine warms up, feel the hoses near the fire wall (the T connections) are they hot?

 

[jdotlim]

Two thoughts:
1) is your thermostat working? If thermostat is stuck open your engine won't get a chance to get to the operating temps and the coolant won't get hot enough to effectively provide heats. The heat gauge in the dash ahould be in the middle when engine warms up

2) Once the engine warms up, feel the hoses near the fire wall (the T connections) are they hot?

Yeah. I changed the thermostat about 1k ago. Hoses get hot. I did all the check list. Final thing was flush heater core. Same temp coming out. Rear still working well.

 

[ClassyJalopy]

Yeah. I changed the thermostat about 1k ago. Hoses get hot. I did all the check list. Final thing was flush heater core. Same temp coming out. Rear still working well.

I will let others chine in but I am afraid it looks like you will need a new core. How did you flush the core and how was the flow?

 

[Rad26rio]

Go read my earlier notes. I had two (2) shops “flush my heater core” to no avail before the last guy soaked it overnight. He actually put a camera in it and could confirm it would “flow” beforehand, just not very well.

If flushing fails, you’ll need a new core installed (major dash surgery).
good luck, I’d soak that sucker hard first....

 

[jdotlim]

I will let others chine in but I am afraid it looks like you will need a new core. How did you flush the core and how was the flow?

the shop flushed it, and said it flowed very well after that. could it be a blend door actuator?

 

[ClassyJalopy]

the shop flushed it, and said it flowed very well after that. could it be a blend door actuator?

That is possible too. I am not sure where to go from here, unfortunately.

 

[jdotlim]

That is possible too. I am not sure where to go from here, unfortunately.

yeah im stumped too. i am going to recheck everything again. it really bothers me now haha

 

[jdotlim]

Go read my earlier notes. I had two (2) shops “flush my heater core” to no avail before the last guy soaked it overnight. He actually put a camera in it and could confirm it would “flow” beforehand, just not very well.

If flushing fails, you’ll need a new core installed (major dash surgery).
good luck, I’d soak that sucker hard first....

Going to CLR myself. Did they mix 50/50? Or 100% CLR to let it sit overnight? Thanks.

 

[chenbowen]

I have exact the same issue as you. Did you find the solution? Thanks

 

[chenbowen]

Yeah. I changed the thermostat about 1k ago. Hoses get hot. I did all the check list. Final thing was flush heater core. Same temp coming out. Rear still working well.

My 2000 LC only has 20-30% heat in front vents, but rear heat vent works well.
The only thing I noticed is when I switch temperature from cool to max heat, the air flow decreases significantly. Might be something wrong with the door? Not the heat core?

 

[PapaGoose08]

I have the same issue. When I switch from cool to heat the air flow decreases. I have flushed the heater core twice, the last time I let it soak in vinegar. I am thinking it might be a blender door issue.

 

[chenbowen]

I have the same issue. When I switch from cool to heat the air flow decreases. I have flushed the heater core twice, the last time I let it soak in vinegar. I am thinking it might be a blender door issue.

I tried to flush heater core as well, only improved slightly. I am guessing the blender door might be the true problem. How to access to that? Major dash Removal?

 

[PapaGoose08]

The FSM says to check the Air Mix Servomotor which is in the passenger side footwell from what I understand.

As an aside, I always use the manual controls not the Auto mode. I just read a thread that said using the auto mode seemed to fix the issue for them. I am going to test that tomorrow.

 

[Rad26rio]

I called my shop about the CLR procedure; they mix it 50/50 with water and pump it into the heater core and insure it gets everywhere and then leave it slightly pressurized overnight. As said before, I had two other shops flush it and though slight gains were made, it didn’t perform to spec until this last shop and their wise actions.

 

[98TLCnoob]

Dear Mudders,

My heat (or lack thereof) has been driving me to the point of wanting to sell my 100. For two years or so I have been battling extremely cold air through the floor vents, in some instances AC in winter, and moderate heat from the top vents. I finally fixed it through a succession of maneuvers. Hopefully this list will help somebody else in this same quandary.

1. Install new thermostat under the hood. While swapping heater Ts, back flush both the front and rear heater cores. This should remove the likelihood of “plumbing” being your issue(s). Rear heat worked like a charm after this step.

2. Replace the sensor that reads cabin heat and insure its vacuum line and electrical are hooked up correctly. This is right behind that tiny grill just under ignition. Photo showing grill and new part ($20 ish).

3. Remove blower fan on passenger side under glove box and make sure it is refuse free and clean running. Access at front footwell is easy, three fasteners.

4. Unconnect and reconnect the electrical connector on the small HVAC servo motor in the passenger floorboard area too. This was critical to my problem, either the connection was bad OR I rebooted this servo in the process. See connector in photo. I did this several times to clean up the connection.

5. Here is the sneaky one. Once the servo motor is now working (by giving differing commands at the dash) observe the metal shaft that is supposed to open and close a flap in the heater box near the servo. This shaft (photo) has a flat section on it for a reason, BUT mine was simply spinning in place. I pried the connection arm (carefully) down to make it seat on the flattened shaft, sprayed dry lube around where shaft entered the heater box, and voila The Heater Box flap began to open and close with the operation of the servo motor. This was an exciting moment!

5. Move your attentions to the dash area above the driver’s footwell. If you look up in there, other arms and flaps exist that need dry lube to work as well. Piece by piece, bit by bit, I managed to get all my flaps working again.

My heat appears to be working now to factory spec and it simply stays set to AUTO and a desired temp and delivers as designed. If you have similar issues, I hope some or all of these steps help you. I couldn’t find any of this on this forum, so decided to share. Happy Holidays.

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I know this thread is old but I seem to have the same issue. Are these photo taken by removing the plastic shields where your knees go? (like the first photo you have shown)

 

[jdotlim]

I know this thread is old but I seem to have the same issue. Are these photo taken by removing the plastic shields where your knees go? (like the first photo you have shown)

so i followed everything he said, with no luck. last thing i did was clear out my lines going to the heater core. that made my heater work!

 

[Phallen]

Dear Mudders,

My heat (or lack thereof) has been driving me to the point of wanting to sell my 100. For two years or so I have been battling extremely cold air through the floor vents, in some instances AC in winter, and moderate heat from the top vents. I finally fixed it through a succession of maneuvers. Hopefully this list will help somebody else in this same quandary.

1. Install new thermostat under the hood. While swapping heater Ts, back flush both the front and rear heater cores. This should remove the likelihood of “plumbing” being your issue(s). Rear heat worked like a charm after this step.

2. Replace the sensor that reads cabin heat and insure its vacuum line and electrical are hooked up correctly. This is right behind that tiny grill just under ignition. Photo showing grill and new part ($20 ish).

3. Remove blower fan on passenger side under glove box and make sure it is refuse free and clean running. Access at front footwell is easy, three fasteners.

4. Unconnect and reconnect the electrical connector on the small HVAC servo motor in the passenger floorboard area too. This was critical to my problem, either the connection was bad OR I rebooted this servo in the process. See connector in photo. I did this several times to clean up the connection.

5. Here is the sneaky one. Once the servo motor is now working (by giving differing commands at the dash) observe the metal shaft that is supposed to open and close a flap in the heater box near the servo. This shaft (photo) has a flat section on it for a reason, BUT mine was simply spinning in place. I pried the connection arm (carefully) down to make it seat on the flattened shaft, sprayed dry lube around where shaft entered the heater box, and voila The Heater Box flap began to open and close with the operation of the servo motor. This was an exciting moment!

5. Move your attentions to the dash area above the driver’s footwell. If you look up in there, other arms and flaps exist that need dry lube to work as well. Piece by piece, bit by bit, I managed to get all my flaps working again.

My heat appears to be working now to factory spec and it simply stays set to AUTO and a desired temp and delivers as designed. If you have similar issues, I hope some or all of these steps help you. I couldn’t find any of this on this forum, so decided to share. Happy Holidays.

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View attachment 1854286

View attachment 1854287

View attachment 1854288

I’ve always had an HVAC issue with the LC but it has been low on the priority list. The heat will periodically work and then stop. The AC does not work, no Freon due to a leak in the system Right now, it blows the same temperature air as outside. I’ve been playing around with it off and on, trying to figure out how to solve it. So far, I’ve cleaned and insured the cabin temp sensor was connected properly; unconnected / reconnected and cleaned the electrical connector to the small HVAC servo along the passenger side floorboards; checked the coolant (it’s filled all the way to the radiator cap), and installed new heater T’s and thermostat (the jiggly pin was positioned at the 12 o’clock).

Today, when I was checking the small HVAC servo along the passenger side floorboards, I saw that it was moving slightly when i adjusted the auto temp from cold to hot and back (see video). Does the servo articulate enough?

Side note, rear heat works very well.

 

[Biga27110]

I’ve always had an HVAC issue with the LC but it has been low on the priority list. The heat will periodically work and then stop. The AC does not work, no Freon due to a leak in the system Right now, it blows the same temperature air as outside. I’ve been playing around with it off and on, trying to figure out how to solve it. So far, I’ve cleaned and insured the cabin temp sensor was connected properly; unconnected / reconnected and cleaned the electrical connector to the small HVAC servo along the passenger side floorboards; checked the coolant (it’s filled all the way to the radiator cap), and installed new heater T’s and thermostat (the jiggly pin was positioned at the 12 o’clock).

Today, when I was checking the small HVAC servo along the passenger side floorboards, I saw that it was moving slightly when i adjusted the auto temp from cold to hot and back (see video). Does the servo articulate enough?

Side note, rear heat works very well.

I believe typically the servo fails you are stuck with just hot or cold. I haven't seen the servo not have enough articulation.

 

[Phallen]

I believe typically the servo fails you are stuck with just hot or cold. I haven't seen the servo not have enough articulatiodoes your service articulate

Thanks, Biga. Is anyone with a functional servo able to see if their’s moves as much as mine?