Anemic heater

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e9999 said:
OK, that's clearer now. There is no hole in the white arm that the pin can get into or indication that there was a bracket of some sort that would couple the 2?
Also, could you move the white arm by hand and see if you get more heat?
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The white arm is driven, and appears to be fine.
Here are two sequence pics that show the driven arm with pin that I suspect should have an arm attached. As you can see, it is driven independent of the white arm. The range of travel in these pics was simply moving the temp selector from high to low, with both of the other selectors in the Auto position. The fact that this arm is driving but does not appear to be transferring that drive to a door is what makes me think there is a missing/broken arm involved.

I really appreciate your interest in this. Its a mystery, and if I could just get eyes on this servo on another car I think it might confirm that I need to remove the servo [which will take some surgery], find the broken arm and fabricate a repair. Talking to Sam at Lowe Toyota, the actuating arms are part of the heater housing. I may need to buy a used housing, pull the dashboard, and swap mine out, but I'm going to try fabricating a fix for the broken arm first.

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Nothing connected to that pin.
I did the same: moved the temp-selector, and the metal part moved. Your pic here is at the coldest position. The pin moves through the gap in the white little arm.
The white little arm also moved a bit, but independent of the metal arm, and not that much, only maybe 10-15 degrees.
APKhaos said:
The white arm is driven, and appears to be fine.
Here are two sequence pics that show the driven arm with pin that I suspect should have an arm attached. As you can see, it is driven independent of the white arm. The range of travel in these pics was simply moving the temp selector from high to low, with both of the other selectors in the Auto position. The fact that this arm is driving but does not appear to be transferring that drive to a door is what makes me think there is a missing/broken arm involved.

I really appreciate your interest in this. Its a mystery, and if I could just get eyes on this servo on another car I think it might confirm that I need to remove the servo [which will take some surgery], find the broken arm and fabricate a repair. Talking to Sam at Lowe Toyota, the actuating arms are part of the heater housing. I may need to buy a used housing, pull the dashboard, and swap mine out, but I'm going to try fabricating a fix for the broken arm first.

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Click to expand...
 
uHu said:
Nothing connected to that pin.
I did the same: moved the temp-selector, and the metal part moved. Your pic here is at the coldest position. The pin moves through the gap in the white little arm.
The white little arm also moved a bit, but independent of the metal arm, and not that much, only maybe 10-15 degrees.
Click to expand...

Many thanks uHu.
Now to find another solution to this problem!!
 
If anyone solves this problem let me know - I took a crack at it last year, but never fixed the problem - I just sort of rely on my rear heat and hope that March and April come around quick
 
Just to add a data point for others who might be trouble shooting a heater issue (sounds like OP got it fixed) is the Auto Climate control... if you set to Auto / Auto and set the temp to a heater value, the blower wont even come on until the coolant is 130*F. Even if you manually select a vent and blower position the air coming out wont be hot until the coolant is up to 130.

On a 35* morning I would have to idle my 100 for 10 minutes to get that. Obviously if you roll out the temp will come up much faster.
 
It's getting colder here, and still no joy. Rear heater is blazing away but front is still useless.
Looks like the only way to check the various doors is by removing the front heater assembly, and that requires removing the entire dash. Not sure I can have the truck down for as long as it will take to do that, and I'm definitely not paying shop rates to have it done. Dammit!
 
I read through this and not sure what to do with mine, The floor is freezing and my girl who has no body fat is uncomfortable being in it on cold days. The defrost gets fairly hot, but not HOT!

Off for more reading.

Shane
 
aaaah, the pleasure of an electrically toasty warm butt when damn cold on a Winter night in Southern California...








(45F :D)









dontcha guys have seat heaters? :)






oh, and yes, the climate auto control sucks on the 03 (did from the get go), the fan will blast you out of the truck in auto mode. What's with that? Very hot or very cold though.
 
Anyone get any resolution to the heater issue? Today mine was blowing hot on the rear floor vent, but could not get good heat on the front foot or dash vents. 9 degrees overnight but drove around for 45 minutes and car would not heat up. Wife's DD so I need to figure this out...
 
BigBlue99 said:
Anyone get any resolution to the heater issue? Today mine was blowing hot on the rear floor vent, but could not get good heat on the front foot or dash vents. 9 degrees overnight but drove around for 45 minutes and car would not heat up. Wife's DD so I need to figure this out...
Click to expand...

Same boat.....
 
I have the FSM inbound, but wanted to get some insights on why the rear overhead heater only blows cold air on my new to me '99. Front heat, dash and floor, works fine. Anything I can check to start diagnosing this while awaiting the FSM?
 
lrowe_csp said:
I have the FSM inbound, but wanted to get some insights on why the rear overhead heater only blows cold air on my new to me '99. Front heat, dash and floor, works fine. Anything I can check to start diagnosing this while awaiting the FSM?
Click to expand...

Because the rear overhead heater is actually the rear overhead air conditioning and does not blow hot air. Consult owners manual.

Rear heat comes from the mid row floor.

Sent from my iPad 2 using IH8MUD
 
BigBlue99 said:
Anyone get any resolution to the heater issue? Today mine was blowing hot on the rear floor vent, but could not get good heat on the front foot or dash vents.
.
Click to expand...

The rear floor vents produce air heated by the rear heater that is a completely self contained unit. The front heater supplies the front dash and floor vents.

You are not alone. A few of us have weak front heater ops, but terrific rear heat. I'm still trying to sort out what is causing my front heater problems.
 
So, my heat kicked back on this weekend now that winter is 3/4 over (even though it never really started). This could be completely unconnected to the issue but I jiggled the heater relay in the fusebox in the engine compartment and a few minutes later I had heat coming from the front vents. Maybe not chicken roasting heat, but it was absolutely hot in the front seats. I was being gentle with the relay as I did not want to break anything but is there a right way to remove them that helps you avoid breakage?
 
Heat wasn't pumping, its cool here in NC today. I found this thread, read it, thought there were some good ideas. Took some things into consideration. Pulled the panels underneath the dash, found the white corrugated tube not attached as it should have been. Put it back on, this time with a zip tie. Dash on, and the heat worked. Literally 15 minutes of my time. What an amazing forum. As the veterans say all the time: the search option is your friend. Thanks to all. IH8mud is the s***!
 
Decided to run this bug to earth last night, now that the weather is getting colder around here.

- Pulled the supply and return lines from the heater core at the engine firewall [near the Tees of Death].
- Blew through the heater core to check for obstructed flow. It was obviously not obstructed, so didn't back flush it as I had intended.
- Checked the supply and return lines to ensure that they were not obstructed. No luck. They were free and clear.
- Checked the heater relay, which tested fine. Swapped it with the MTR1 relay which is the same type in the adjacent socket in the '99 engine bay fuse box.
- Pulled the DS lower panel to check the temp sensor hose connection. It was fine, but the thermistor [the temp sensor] was covered in 12 years of dust and crud. Carefully cleaned this up with a soft bristle brush and some IPA/water spray.

GOOD NEWS: I now have full strength heat from the front heater to all ducts. All air distribution settings work perfectly.

LESS GOOD NEWS: I'm convinced that the heater core work did nothing but confirm that the heater core was OK. Also not 100% sure which of the next two steps cleared the problem - the relay swap or the temp sensor cleanup. Best bet is the temp sensor. There may have been enough crud to prevent it sensing cabin air temp accurately. More likely is that the contacts that connect the two sensor legs to the harness connector were also dirty.

Just took it out for a quick errand, and the cabin was toasty warm in a few minutes - just like old times!! :beer:
 
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Past topic but last Friday, we were taking kids to see snow. Heater warmth was pathetic. Reading this thread had me check the hose behond the sensor. Sure enough it was off. The sensor was clean at 11 yrs of age. Full heat returns. Thanks for this info.
 
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