cabin heater control

Mattt · November 15, 2005

The heater in my truck works.....usually too well. It seems like I have no heat control. Like its either on or off. Sometimes I turn up the temp knob just a bit, like to where the blue and red meet, and it smokes me out. Should the heater control be a graduated control(more to left = cooler).....I thought so.

What Ive come to doing now is run the heater just for a bit(usually with no fan and either on the dash or feet outlets), then turn it off so I dont cook from the inside out.

Normal? If not, what takes care of it?

TIA

Mattt · November 19, 2005

bump

Anyone else notice this problem?

Mattt · November 30, 2005

top.

Is there something that can go out causing the heater to be either ON or OFF with no graduated heat control?

Back up a bit....is there NO GRADUATED HEAT control with the center heat control knob?

Im wondering why there has been no attention given to this thread.

n5xl · November 30, 2005

For reference on my 01 1500, I typically turn the knob up two or sometimes three clicks from completely horizontal on the temperature control to get what I can just detect as warm air out of the vents. This has my pointer very much in the blue zone, and still pointing very much to the left. If I were to put the pointer straight up, I'd have fairly hot air coming out the vents. Of course your outside temperature and engine temperature of course affect where you finally have to set your control for comfort, and this is about as subjective as you can get because what you consider hot is likely totally different from my idea of hot. For instance, when its cold out, I may end up with the pointer setting at about 10 or 11 o-clock for comfort.

In a totally quiet location with your truck off, turn the ignition switch to on and move the HVAC controls. You should be able to hear the doors opening up and closing as you pick different temperature settings. If your stepper motors are working, you should be able to just hear them or the doors moving around. If you have that, then I would consider yours normal. If you have full heat with the temperature set to off or just one click, I'd say your heater doors are not working right.

GM-Tech · November 30, 2005

Manual or automatic air? Dual zone temp controls or single?

Mattt · November 30, 2005

Thanks for the replies from both. Its seems like with mine if I get anywhere near where the red meets the blue(about 10 o clock on the dial) Ive got a lot of heat. Maybe this is just how 01's are. Because where you said you have a little heat(still in blue zone), mine seems like that too. Straight up is a lot(too much) of heat. Ive never had it past straight up for more than a minute. I cant imagine how much heat from 12 to 5 o clock would put out. This is the original point of my post. Seems like you are almost all in(heat wise) before/at 12 o clock on the dial.

Can you hear the doors moving in relation to temp adjustment, or is that just for where the air comes out? defrost dash/front of dash/floor?

Manual single zone ac/heat controls. Its on an 01 2500HD CC(first year of NBS).

GM-Tech · November 30, 2005

Its seems like with mine if I get anywhere near where the red meets the blue(about 10 o clock on the dial) Ive got a lot of heat.

Is this with the a/c off? If so, I would say it's probably normal. But, you have to understand we don't deal with heater issues here in South Florida, just a/c, so I don't have a whole lot of experience in that area.

Mattt · December 1, 2005

Yes, this is with A/C off. Here in Southern CA I dont use the heater much either, but when I do, it seems like its ON or OFF. I wish it had more of a graduated control.

Is there a way to verify if turning the knob is successively opening the "heat can" more and more, or if its opening it full? When I turn the knob, what is going on down below?

00Tahoe · December 8, 2005

Don't know if you fixed it yet but I had the same problem. Here was my fix. My friend and I located the motor which controls the door to control the amount of heat that comes through. It is located just above the hump under the dash, fairly easy to get to. Apparently when things get hot, the metal shaft inside the black motor box swells up and will not allow you to control temp of the air because it is now bound in its plastic slots. We took the motor apart and lightly sanded the shaft to allow for this swelling when it got heated up because basically it has hot air blowing on it from the floor vent.

This fixed my problem. Are you able to turn your car off and say go inside for about 5-10 min. and come back outside and control the temp again with no problems until it heats up again? If so, chances are you have the same problem that I did. The cost for this repair was time.

Mattt · December 8, 2005

Don't know if you fixed it yet but I had the same problem. Here was my fix. My friend and I located the motor which controls the door to control the amount of heat that comes through. It is located just above the hump under the dash, fairly easy to get to. Apparently when things get hot, the metal shaft inside the black motor box swells up and will not allow you to control temp of the air because it is now bound in its plastic slots. We took the motor apart and lightly sanded the shaft to allow for this swelling when it got heated up because basically it has hot air blowing on it from the floor vent.

This fixed my problem. Are you able to turn your car off and say go inside for about 5-10 min. and come back outside and control the temp again with no problems until it heats up again? If so, chances are you have the same problem that I did. The cost for this repair was time.

<{POST_SNAPBACK}>

Thanks for the response. When you say located just above the hump.....do you mean the center trans hump in the floor? Any way to know Im looking in the right area. Any tell tale signs to look for with this motor?

I have experimented with it a little bit. I think it might just be that the heater on these trucks is too much for moderate temps Southern CA. I started by turning up the heat control one click at a time while driving. I had my hand over the vent to feel for temp differences. By 3-4 clicks up I was feeling warm air. By 8 clicks up(close to straight up) it was too much heat for my liking. I guess for moderate climates you just never have the heat control past straight up. Anything past 12 o clock(from 12 to 6) was just TOO much heat. It cooks me out at that setting.

Id still like to check the motor control that was mentioned though.

00Tahoe · December 9, 2005

Yes, above the center driveshaft hump. You will have to remove the plastic covering that is just above the passengers feet to get to the motor. Personally, I agree that it puts out too much heat for my liking past 12 o'clock. I just couldn't take not having control of the heat after a certain point when putting the control all the way down on the left (blue) and heat was still coming out of the vents.

Caprice89 · December 8, 2006

Hi there,

I have the same on my '01 Silverado and I drive my car in the Netherlands, Europe. Not exactly a warm climate... The temperature is very hard to adjust. Someone suggested to me to completely power down the car (batt. disconectted), so the controls will re-adjust. I did, but no effect. I will check the door control motor.

On top of that, I have the A/C Switch in the off position (light off) but still I can hear the A/C kicking in, from time to time. Could there be a relation?

wgabert · December 10, 2006

Hi there,

I have the same on my '01 Silverado and I drive my car in the Netherlands, Europe. Not exactly a warm climate... The temperature is very hard to adjust. Someone suggested to me to completely power down the car (batt. disconectted), so the controls will re-adjust. I did, but no effect. I will check the door control motor.

On top of that, I have the A/C Switch in the off position (light off) but still I can hear the A/C kicking in, from time to time. Could there be a relation?

<{POST_SNAPBACK}>

The A/C will cycle on and offf when the heater control is in the defrost position

Ben63 · December 10, 2006

I have the same problem with my 01 Silverado.

snotime · December 23, 2006

I've got the same problem but at the opposite end of the spectrum. I'm stuck on cold! The other day I was heading to work and I tryed turning the temp down because it was getting to hot. After I turned it all the way to the blue zone I still had full heat coming out. Then a couple hours later I left my job to go run an errand and it was blasting out cold air. I live in NY and while it has been a mild winter so far, you still need the heat! So I turned it up off cold to full heat. It never changed. Now all I have is cold. It has been that way for a week now so I guess I'll have a look at the heater door control like was mentioned.