Is this normal? Every time I turn the heat control **** up a large amount on 04 with climate control, the system goes into the recirculate mode and the air conditioner light comes on and the compressor kicks in. I know the compressor should kick in when using the defroster, but not every time I turn the heat up. Do I have a climate control head problem?

 

My '03 does that too. I just figured it had to all work together to perfectly get to the correct temperature. Don't really know for sure. Would love to hear some expert analysis.

 

What mode is it in? I believe the default has the defroster on....

 

I have the same problem. Weather could be 60 degrees outside, I turn the heat up to 80-90 degrees and the AC light goes on. What a bugger. I've got the automatic climate control system with the independent passenger zone. It doesn't feel humid and there is no moisture on the windows, still the AC comes on.

I looked at the little temp sensor and cleaned it (a little) including the contacts. Don't think this is it b/c it doesn't appear to have a humidity sensor.

 

I seems to do it in any mode. It sounds like they all do it. I looked through the owners manual. It says nothing about doing this though.

 

Makes me really glad I have the old fasioned hot or cold system. I have the climate control on my other cars and I hate it.

 

my 99 does the same thing. I can't figure out if its normal or something is out of wack with it. It doesn't make any sense to me that when its cold outside and I turn on the auto mode I always get the AC light. I've tried to hit the button to turn it off, but it just flashes for a second then comes back on again.

btw I do have a DTC on my climate control, it said interior temp sensor open circuit. I thought that was responsible, but it sounds like everyone else is having this problem also. Any further ideas?

 

ha ha ....whew.... that is great to hear...I thought I was the only one that didn't understand the Heater/AC.

 

don't use the Auto feature . set it to manual wherever you want it to blow .
and then if you have memory seats , set your memory to the new setting . seat memory button also memorizes the AC settings for whatever keyfob you unnlock the door with .

 

Yeh that kinda drives me crazy, if i hit the auto and no matter what temp the ac light comes on..Ive been using manual and it will stay off. Kinda frustrating.

 

I really appreciate this thread and I'm glad this topic got brought up. To this day, I have not figured out EXACTLY how the automatic climate control system is so supposed work. Incidently, I have read the manual several times over and it is written horribly!!

Some of the things people are saying, like the A/C light coming on when you're in heat. Or, what if you want to blow just cold air from the outside without the A/C on... seems you have to turn the A/C button off. I haven't figured out how AUTO is supposed to work. I would think if it is too hot or too cold, it would AUTOmatically blast hot or cold air (assuming the car is fully warmed up), but it never does. The comment about the seat memory, I will check that out. Here's one for y'all... is the air supposed to flow equally hard out of all vents? I find the passenger Vents work the best. The big center vent is not as strong.

I didn't mean to hijack this thread with all these additional questions, it's just that I'm glad I am not the only confused by the automatic climate control system.

 

It's normal.

When you turn the HVAC on in auto mode it defaults into defog to remove moisture from the cabin if the sensor senses that its needed. It'll switch to regular mode once its done that. You can override into manual at any time by selecting another mode or fan speed.

It also doesn't blow on max setting until the engine warms up to avoid blowing cold air. You also get a higher flow in recirc mode.

 

Mine too.

I think my ford does it to. As long as it has gas and is clean I do not care much else about it.

The Vette I care very much about and Iv herd its normal.

Paul G.

 

well that makes me feel much better. maybe I'll give the auto mode another try and see if its going to work any better now? I still may have a problem because of that one DTC my system had. I'm just glad the whole thing isn't screwed up, I bought my 99 with the Climate control LCD is always dim problem which is fairly common. I figured it would be a quick fix in a car priced well below its value. I got it fixed and then found out that Auto mode always turns on the A/C! seemed strange to me. well this is good news! on to the next problem with my car... :-(

 

Auto mode assumes you want the temperature and humidity controlled. When the AC light is on it does not necessarily mean the compressor is on. The compressor is turned off when outside air temps are below 38 degrees or when the high side pressure gets too high. The system works on the cool and reheat principle. Here is the Service Manual description of Auto mode works.

Heating and A/C Operation
The purpose of the heating and A/C system is to provide heated and cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. The vehicle operator can determine the passenger compartment temperature by adjusting the air temperature switch. Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve the desired temperature:

Recirculation actuator setting
Difference between inside and desired temperature
Difference between ambient and desired temperature
Blower motor speed setting
Mode setting
The control module makes the following actions when automatic operation is not selected, and an air temperature setting is selected:

When the air temperature switch is placed in the warmest position, the control module commands the air temperature door to divert maximum air past the heater core.
When the air temperature switch is placed in the coldest position, the control module commands the air temperature door to direct air to bypass the heater core.
When the air temperature switch is placed between the warmest and coldest positions, the control module monitors the following sensor inputs to determine the air temperature door position that diverts the appropriate amount of air past the heater core in order to achieve the desired temperature:
Sunload
Ambient temperature
Inside temperature
The A/C system can be engaged by pressing the A/C switch. The A/C switch will illuminate when the A/C switch is pressed to the on position. Pressing the A/C switch the control module grounds A/C request signal circuit from the powertrain control module (PCM). The following conditions must be obtained before A/C compressor engagement is allowed:

The engine coolant temperature (ECT) is less than 121°C (250°F)
The engine RPM is more than 550 RPM
The A/C pressure is between 207 kPa (30 psi) and 2826 kPa (410 psi)
The A/C request signal circuit is grounded.
Once engaged, the compressor clutch will be disengaged for the following conditions:

The throttle position is 100 percent
The A/C pressure is more than 2826 kPa (410 psi)
The A/C pressure is less than 207 kPa (30 psi)
The engine coolant temperature (ECT) is more than 121°C (250°F)
The engine speed is more than 5,500 RPM
The transmission shift
The PCM detects excessive torque load
The PCM detects insufficient idle quality
The PCM detects a hard launch condition
When the compressor clutch disengages, the compressor clutch diode protects the electrical system from a voltage spike.

Automatic Operation
In automatic operation, the HVAC control module will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, the mode actuator and the recirculation actuator.

To place the HVAC system in Automatic mode, the following is required:

The Auto switch must be activated
The air temperature switch must be in any other position other than full hot or full cold position
Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically be adjusted to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature:

Monitor the following sensors:
Inside air temperature sensor
Ambient air temperature sensor
Sunload sensor
Regulate blower motor speed
Position the air temperature actuators
Position the mode actuator
Position the recirculation actuator
Request A/C operation


Bill

 

awesome, thanks for that info! I guess I'll just stop worrying about it now. GM should have designed the thing differently so people wouldn't so confused. let it do its thing normally but leave the A/C LED off any time the desired temp is higher than the actual temp so it isn't so confusing. I've been missing out on the auto mode because I thought it wasn't working right.