Anemic heater

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Mendocino

Mendocino

10 Year 15 Year 20 Year OG
Joined
May 15, 2002
Threads
22
Messages
380
Location
Colorado
I find the heater in my new to me 100 to be a bit anemic. All the HVAC seems to work properly and blow from the right places, the heat just never gets really hot. Is this normal?

I searched a bit but did not see this particular issue. Any help would be appreciated.
 
Mendocino said:
I find the heater in my new to me 100 to be a bit anemic. All the HVAC seems to work properly and blow from the right places, the heat just never gets really hot. Is this normal?

I searched a bit but did not see this particular issue. Any help would be appreciated.
Click to expand...

You have an 03+ with the push buttons? On my 2000 the round dial doesn't directly control the output, it controls the set point for what is essentially a t-stat. I've found that once the vehicle heats up it takes a progressively higher temp setting to maintain the same temp output air. Me thinks this is because the temp sensor (by your right knee) is picking up heat from the floor output rather than true ambient temp.
 
OregonLC said:
You have an 03+ with the push buttons? On my 2000 the round dial doesn't directly control the output, it controls the set point for what is essentially a t-stat. I've found that once the vehicle heats up it takes a progressively higher temp setting to maintain the same temp output air. Me thinks this is because the temp sensor (by your right knee) is picking up heat from the floor output rather than true ambient temp.
Click to expand...

Interesting. My wife says that she usually turns the heat off the floor and turns on the vents above floor level and it seems to get hotter. This would support your suggestion OregonLC.
 
If the automatic system is set then it will not operate the heat until the coolant is up to temp. This is a nice feature because it never blows cold air on you.

Otherwise I could roast weenies with the heat on my 100 and if you aren't getting heat once the engine is warmed up then there is some problem. Maybe a blocked heater core.

Bad thermostat might show up as slow to warm in cold weather.
 
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Mendocino said:
Interesting. My wife says that she usually turns the heat off the floor and turns on the vents above floor level and it seems to get hotter. This would support your suggestion OregonLC.
Click to expand...

Personally, I'd rather have it be direct heat control rather than a t-stat, but no biggie, I can make it work just gotta learn the technique.
 
I went out earlier (between turkey bastings) and ran the vehicle from a cold start with the owner's manual suggested settings for maximum heat. It just did not get hot. I tried the rear HVAC and it would only blow when I had the AC on.

I have the FSM and will have to sort out what could be going on: bad ambient temperature sensor up front or in back; blocked or non-functioning heater core; ?.

Additional suggestions are appreciated. BTW-the AC works fine.
 
Have you/someone else recently worked on the coolant portion of the engine? Thinking if so there might be an air bubble.

Did you feel, once the engine is hot, the upper radiator hose to engine to verify if its hot or not? Ditto for the heater hoses at the rear of the intake manifold? If both of these are cool to the touch with a hot engine it would point to a stuck t-stat.

How long have you owned this rig? Does the radiator show any signs of leakage where possibly a PO had thrown in stop leak or similar that might have drastically plugged the heater core?

As the others attest: My heater will blow you out of the rig...
 
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Jamomac said:
Where is the temp sensor? I have the exact same problem - my heat blows - just not hot always luke warm. I've already checked the radiator, no issues there
Click to expand...

The front sensor is by your right knee (slits in the panel), the rear is overhead in the center near the rear HVAC controls.
 
I have had this vehicle about 6 weeks; I have not done anything to the cooling system; however I do know that the 90K service was done (twice!) which makes me think that the guy that did the service was not the smartest (not a Toyota dealer).

This morning I checked the coolant level, which was low and not the red Toyota coolant. I topped it off and started the vehicle cold. It was 46 F in my garage. I used a thermometer inside the heater vent and it read 58F. After starting the vehicle and letting it run a while it got to 74F in the vent. The engine temperature gauge read well above "C". When I felt the radiator hoses it felt like the thermostat had not opened.

After about 20 minutes the heat blew at 84F and the engine temperature was right between "C" and "H." I used a laser thermometer and the coolant on the engine side had not reached 82C which is when the thermostat is supposed to open according to the FSM.

Since the heater hoses are on the engine side and not on the radiator side I am led to believe that there is an obstruction in the heater hoses or heater core. More later...
 
I think a high speed, high RPM run is called for to get the coolant flowing well and eliminate any air pockets in the system that might cause reduced flow to the heater core. You also need to see if the thermostat is opening and it may never at idle with this week's temps.

Start with the vehicle cold, radiator cap off and fill, then fill the overflow tank to full mark.
 
NMuzj100 said:
I think a high speed, high RPM run is called for to get the coolant flowing well and eliminate any air pockets in the system that might cause reduced flow to the heater core. You also need to see if the thermostat is opening and it may never at idle with this week's temps.

Start with the vehicle cold, radiator cap off and fill, then fill the overflow tank to full mark.
Click to expand...

I did the latter earlier this morning. I'm about to drove from Broomfield to Winterpark so the high speed suggestion will be completed.
 
I might suggest a slow speed, high-torque extended hill climb over a high-speed run. At least here it's quite cold and faster speeds may act to help the radiator.

Regarding t-stat opening at idle, I agree. I can get cabin heat at idle, but it's not until I'm on the road that the needle comes up and the t-stat starts to open.
 
Some steep inclines and declines with high RPMs could also let gravity move some air around . Maybe a trip to a mountain ski town would work ....

Start with cardboard on the grill until you know you have gotten temps up and thermostat has opened ?
 
It's blowing hot now. I took a thermometer and it was blowing at 108F this morning on the way to pheasant hunting. I think the combination of very cold weather and an air bubble in the cooling system created the issue. Earlier in the week the engine was just not getting warm enough even though I was driving pretty long distances.

Using a piece of cardboard when it is less than 20F may be a good idea. I guess I'll need to cut some carbdoard...:rolleyes:
 
So I think I found the problem:

There's a corrugated hose that comes off the back of the front room temp sensor. Mine was missing. One of the PO's had a trailer brake and when it was removed the hose probably came dislodged (there's no clamp). I'm not certain, but it appears that the HVAC pulls a constant flow of cabin air across the sensor bulb. Without the hose it's only a local reading and because it's next to the duct it get's warm and fools the HVAC into thinking it's warmer in the cabin then it is.

Hose from the side in the first pic and head on in the 2nd. I'll post back after I drive her a while to see if things change.

IMG_2312.jpg


IMG_2310.jpg
 
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