[fridapaz]

Hi. I've been having problems with the heating system. Now that the colder weather has descended on the NE, I've been turning up the heat to read 72 degrees. However, it just blasts coldish air from the vents. I have to crank it up to 78 before I get heat sometimes. At other times, I get a lot of heat when the computer reads 68 degrees! has anyone else had this problem/ Can anyone explain what's happening?
Thanks! :?:

 

[hyperion]

Nobodies perfect. That's why I figure they give us the option of raising and lowering the "temp numbers". I notice I have to occasionally play with the temp numbers on my electric blanket controls also.
I have noticed this and have just raised or lowered the numbers to support the occasion. It usually straitens itself out. I figure it's a Japanese thing and NBD.

 

[redwein]

Hi. I've been having problems with the heating system. Now that the colder weather has descended on the NE, I've been turning up the heat to read 72 degrees. However, it just blasts coldish air from the vents. I have to crank it up to 78 before I get heat sometimes. At other times, I get a lot of heat when the computer reads 68 degrees! has anyone else had this problem/ Can anyone explain what's happening?
Thanks! :?:

My dad had this same problem in a Jaguar S-Type. I told him he was crazy since raising and lowering the temp did have some control on it. I explained about the difference between actual temp and apparent temp, blah, blah blah. It turned out he was right. There was a faulty temp sensor somewhere so the system was using that bogus data when determining how much heat or cooling to provide. It was good to see my dad beat me in a discussion for a change. Bottom line, I would get it checked out.

 

[DanMan32]

Point to note though, the HVAC does use fuzzy logic to provide a 'feels like' temp equal to your setting.
Sensory inputs include cabin temp sensor, cabin humidity sensor, outside temp sensor, and a solar radiant heat sensor.
Using the temp you selected, and the inputs described above, it controls the AC compressor speed, cabin fan speed, vent selection, recirc control, coolant flow in heater core, and electric heaters to achieve your desired 'feels like' temp.
The electric heat is moderate, and there to provide some heat until the engine coolant gets hot enough to provide you with heat.

 

[redwein]

Point to note though, the HVAC does use fuzzy logic to provide a 'feels like' temp equal to your setting.
Sensory inputs include cabin temp sensor, cabin humidity sensor, outside temp sensor, and a solar radiant heat sensor.
Using the temp you selected, and the inputs described above, it controls the AC compressor speed, cabin fan speed, vent selection, recirc control, coolant flow in heater core, and electric heaters to achieve your desired 'feels like' temp.
The electric heat is moderate, and there to provide some heat until the engine coolant gets hot enough to provide you with heat.

That's exactly what I told my dad. But I think having to go all the way to 78 to get any heat sometimes and getting a lot at 68 at other times, assuming similar temps otherwise, sounds a little too erratic to be explained by fuzzy logic. This can also be a pain to get diagnosed because the techs assume, like I did, that the fuzzy logic was a sufficient explanation. Throw in the fact that my dad is 80 years old and he didn't have a chance. Fortunately it got worse so that I, and the techs, had to agree that it was broken.

 

[DanMan32]

I guess this would be justification for providing user displayed in cabin temp and humidity.

 

[Sanny]

I guess this would be justification for providing user displayed in cabin temp and humidity.

and wind chill...

 

[Tideland Prius]

It'll take into account outside temperature. Setting my climate control at 22°C in the summer gives me cold air while that same degree gives me nice warm air in the winter. Theoretically, I don't have to touch the temperature setting at all!

 

[mrv]

With the auto fan setting on my Classic, the fan speed will be slow to start out, and will get warmer/faster once the engine has had time to warm up. No point blowing cold air at you when you want heat...

 

[redwein]

I guess the original problem could be explained by impatience. It's not poosible to tell with the information given.

 

[DanMan32]

Also don't forget the solar radiant heat sensor. If the system thinks the sun is doing the heating, it will act accordingly. At least it uses that sensor for cooling, not sure if it influences heating.

 

[benighted]

Hi. I've been having problems with the heating system. Now that the colder weather has descended on the NE, I've been turning up the heat to read 72 degrees. However, it just blasts coldish air from the vents. I have to crank it up to 78 before I get heat sometimes. At other times, I get a lot of heat when the computer reads 68 degrees! has anyone else had this problem/ Can anyone explain what's happening?
Thanks! :?:

Mine does pretty much the same thing. After the car warms up at first the setting for 72 degrees is pretty warm but after about 15 - 20 minutes that same setting feels a lot cooler. I usually just set it at 74 when that happens and then back to 73 after it evens itself out. It takes a bit of patience but I guess if you really want it to heat up quicker you can set it to 78 for a while.

 

[G. McCurdy]

Check in the Climate window and see if the vent is set to Outside Air instead of Recirculate (i.e. inside) air. I find when it seems like the air is cooler, the vent is set to Outside. This may be something to due with the Auto A/C control or defrost.

 

[Astrowoman]

I find the outside temp makes a huge difference both in the actual performance and my percieved comfort level -- same thing happens with the thermostat setting in my house. The colder it is outside the warmer I have to set the heat to be comfortable and in summer the hotter it is outside the lower the thermostat has to be set.

In the car I just tweak the setting until I'm comfortable. I also look at what it thinks the outside temp is and make sure if I want heat I've set the target number at least 5 deg F higher than it thinks the air outside is. Sometimes if the difference is small and the car is in high fan mode the air being circulated feels cooler than it actually is.