HVAC question

[mcbean7]

Hi guys.
I notice that everytime I start the car the recirculation button is illuminated. Even if I turn it off to get fresh air from outside it goes back to this "default" setting when the car is restarted. Is there a way to set this so it stays on "fresh air from outside" until I want to manually turn on recirc?

 

[jbrhymer]

Hi guys.
I notice that everytime I start the car the recirculation button is illuminated. Even if I turn it off to get fresh air from outside it goes back to this "default" setting when the car is restarted. Is there a way to set this so it stays on "fresh air from outside" until I want to manually turn on recirc?

make sure the auto setting is off

 

[Koz]

There are sensors that determine what will be the most effective way/settings to achieve the set temp under the current conditions, so the settings will vary.

Koz

 

[Iowa4Runner]

Hi guys.
I notice that everytime I start the car the recirculation button is illuminated. Even if I turn it off to get fresh air from outside it goes back to this "default" setting when the car is restarted. Is there a way to set this so it stays on "fresh air from outside" until I want to manually turn on recirc?

I've noticed that even in manual mode, if the temp setpoint is on "lo", the system always starts in recirc mode. The only work around I know of is to avoid the "lo" setting. Try 65 if you want cool air.

From an HVAC controls standpoint the operation of the recirc mode is simply poor engineering. It has annoyed me since day one. I also hate the fact that you don't get a true manual mode. I've thought about reworking the whole system but I just don't have time. I just have to accept that Toyota screwed up and live with it.

 

[Iowa4Runner]

Re: Re: Re: HVAC question

I almost always use the manual mode. Why do you say that it's not a "true" manual mode? The only glitch seems to be the recirc setting that goes into default mode (on), but that only happens if you have the temperature set to low. Other than that, it sure seems like a proper manual mode to me.

In true manual mode (like the good ol' days) the temperature dial directly controlled the temperature of the supply air (the air blowing out of the vents). With the 4Runner's manual mode, a closed loop controller controls the temp of the supply air and adjusts it keep the cabin temp at the setpoint.

 

[mcbean7]

Thanks for your advice, guys. I'll just keep the temp at 65 for cold air. Being here in Arizona...that's almost all the time!

 

[Koz]

Manual mode works fine. You have complete control of temp, flow direction and speed. The recirc mode is default because it is easier/faster to regulate the inside air temp rather then the outside. The only time you would want outside air is when you want to vent without heat or cooling. The system is designed for max efficiency and auto climate control without much fuss.

Koz

 

[Iowa4Runner]

Manual mode works fine. You have complete control of temp, flow direction and speed. The recirc mode is default because it is easier/faster to regulate the inside air temp rather then the outside. The only time you would want outside air is when you want to vent without heat or cooling. The system is designed for max efficiency and auto climate control without much fuss.

Koz

You have complete control of what temperature? Sometimes recirc actually switches OFF when it shouldn't, it has nothing to do with regulation or response time. Maybe the 2005s are different. But the 2004s do not have true manual control, and sometimes the recirc operation is a flat out screw-up. Trust me, I worked as an HVAC controls tech. for 5 years, I'm not making this up...

 

[Koz]

You manually control the temp by raising or lowering the digital number. When ever you make a temp adjustment, the system looks for the fastest/easiest using the sensors and automatically makes changes to speed and direction. You then have to reset the fan speed, direction and possibly the recirc mode manually and it should stay there as long as the auto function is off. Maybe there is something wrong with your truck's system.

Koz

 

[Iowa4Runner]

You manually control the temp by raising or lowering the digital number. When ever you make a temp adjustment, the system looks for the fastest/easiest using the sensors and automatically makes changes to speed and direction. You then have to reset the fan speed, direction and possibly the recirc mode manually and it should stay there as long as the auto function is off. Maybe there is something wrong with your truck's system.

Koz

It sounds like you're running in auto mode.

Keeping the temp setpoint at a fixed number, say 70, can result in a huge variation in supply temp over the course of a trip to work. This is not a true manual mode.

 

[khaug]

From an HVAC controls standpoint the operation of the recirc mode is simply poor engineering. It has annoyed me since day one. I also hate the fact that you don't get a true manual mode. I've thought about reworking the whole system but I just don't have time. I just have to accept that Toyota screwed up and live with it.

Well said! The automatic climate control system is just terrible. In "manual" mode, our '03 will turn on recirculation when the cabin temp is 100 degrees and the outside air temp is 70 - exactly the last thing you want! And in automatic mode, it spools up the fan speed to B-29 noise levels and leaves it there forever.

The "engineer" that designed this should be made to live with it for the length of time most of us have to keep a truck we've bought and paid for.

 

[Iowa4Runner]

From an HVAC controls standpoint the operation of the recirc mode is simply poor engineering. It has annoyed me since day one. I also hate the fact that you don't get a true manual mode. I've thought about reworking the whole system but I just don't have time. I just have to accept that Toyota screwed up and live with it.

Well said! The automatic climate control system is just terrible. In "manual" mode, our '03 will turn on recirculation when the cabin temp is 100 degrees and the outside air temp is 70 - exactly the last thing you want! And in automatic mode, it spools up the fan speed to B-29 noise levels and leaves it there forever.

The "engineer" that designed this should be made to live with it for the length of time most of us have to keep a truck we've bought and paid for.

Yeah just the other day I was driving along on a sunny but cool day (~50 deg F). It was a little warm in the cabin so I lowered the temp setting from 70 to "lo" and the system went into recirc mode. Brilliant!!!

You know the system has design issues when rolling the window down gives better results than adjusting the temp setting.

I also have gripes about the transmission control algorithm, but I suppose I've complained enough for one thread...

 

[cdoyle]

It sounds like you're running in auto mode.

Keeping the temp setpoint at a fixed number, say 70, can result in a huge variation in supply temp over the course of a trip to work. This is not a true manual mode.

This annoys me to no end, every winter it seems like I'm always trying to adjust the temp, because the air coming out the vent is never constant.

I would like it to just blow out the temperature that is says on the display. Not try and compensate for the cabin temperature. It's so annoying!!

 

[Koz]

All I can say is, I found a comfortable auto temp setting and I very rarely have to re-adjust, and anytime I use manual it works fine. I also think the controls are really simple and well laid out. Just my opinion.

Koz