# Heater always "on" in 1998 Bravada



## Shari (Jun 2, 2011)

Okay, folks, I need some car repair advice.

My heater is always 'on' in my 1998 Bravada.  I spoke to mechanic friend who lives 4 hrs. away and we have determined it is a problem with the air mixer.  I can sometimes hear what sounds like a door creaking open and closed under the center of the dash.  I can't turn the A/C on because the heat is always on.  All heater controls (fan & temp) are turned off but air still is blowing hot.

I found two methods of repair:

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1.  Apparently the GM repair manual has this rated as a 5 hr job, removing the entire dash (mega $$ for repairs), or

2.  From here:  http://classicoldsmobile.com/forums/bravada/1329-98-bravada-auto-climate-control.html

"However I did find the problem. The actuator that moves the air mix door from the heat to cool side goes into a mode where it will not move. This can be caused my the door sticking. Under the hood on the housing to the heater/ ac unit there is an area marked. "Cut for service". After removing the area marked there is an access panel with 3 screws. Remove this panel and you will see the air mix door. I manually moved the door from heat to cool a couple times until it didn't feel like it was binding. Do this slowly because the actuator is an electric motor to gear arrangement. GM wants about $120 for the actuator. They are available on ebay for around 35 plus shipping. 
Anyway, after moving the door I started the Bravada and selected a mid temp. The mix door moved to a mid way position. I then selected all the way cold and the door moved to block off the heater core. Selecting all the way hot and the door moved to block off the AC side. 

If you do have to change the actuator it can be gotten to by opening the glove box all the way. There is a metal loop on the upper left of the opening that prevents the box from swinging all the way out. The loop will swing out to allow the box to open all the way (and dumping its contents on the passenger floor). 
You then can look on top of the heat unit and see the actuator. It is on top back by the firewall. It is held in place by 3 screws and has the control wire plug attached. Removig the screws and moving the actuator up will release it from the air mix door. Then just unplug the control wire plug."

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Due to $$ constraints, number 2 above sounds like something I'd be willing to tackle - but - I'd like to see a manual with diagrams before I get into this.  Does anyone have a suggestion for a service manual?

Shari


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## kettensÃ¤ge (Jun 2, 2011)

Search the Blazer forums as well, same vehicle.
My brother changed the actuator in his Blazer, not a big deal, did it from under the dash. 

Autozone will let you look at Haynes manuals at the store. Not sure if this is in a Haynes though. 
Check E Bay, you can sometimes find manuals on CD for less than $10.


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## semipro (Jun 2, 2011)

If you're only concerned about the hot air coming out a quick fix would be to clamp off one of the hoses going to the heater core.  This will stop the flow of hot water and the resulting heat.  You can take the clamp off when it gets cold again.


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## SolarAndWood (Jun 2, 2011)

Thanks Shari, my 01 burb does the same thing intermittently and the shop hasn't been able to find the problem.  I am going to go after option 2 myself.


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## Shari (Jun 2, 2011)

After posting my initial question, I also found the following which I thought I'd post in this thread as another possible fix which I will try this morning:

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Hello and welcome to just answer,
From your symptoms it sounds like the noise you hearing is your temperature control actuator cycling from hot to cold. It could be that it is out of calibration, or it could have a problem.
There is a recalibration procedure that you could perform yourself. It involves removing a fuse and replacing the fuse, letting the controller recalibrate the actuator.
I would like you try this first this way we can tell if we have a problem or if it is just out of calibration.
Here's the procedure, and some information from GM.
Calibration of the electronic climate control (ECC) module occurs whenever B+ is removed and then restored to the ECC module. During this calibration process the ECC module will automatically command the temperature door to the full HEAT position and then to full COLD postion. The ECC module records both positions and uses this data to determine temperature door settings based on customer selected temperature settings.
Turn the ignition switch to the OFF position.
Remove the RDO BATT fuse for 10 seconds and then reinstall the fuse.
Place the ignition switch in the RUN position and wait 40 seconds for the ECC module to initialize
Do not attempt to adjust any controls on the controller while the module is initializing.
Cycle the ignition switch back to off and then start vehicle and check for proper operation.
The RDO BATT fuse can be found in the under hood fuse block.
Let me know what happens
Scott
Scott K39612.921966088

Read more: i have a 1998 oldsmobile bravada with the comp. climate ... - JustAnswer http://www.justanswer.com/car/192vw-1998-oldsmobile-bravada-comp-climate.html#ixzz1O5N4DlwP


http://www.justanswer.com/car/192vw-1998-oldsmobile-bravada-comp-climate.html


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## SolarAndWood (Jun 2, 2011)

Kind makes me want to go back to the days when the thing you turned had a cable connected to the thing you wanted to adjust.


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## Highbeam (Jun 2, 2011)

SolarAndWood said:
			
		

> Kind makes me want to go back to the days when the thing you turned had a cable connected to the thing you wanted to adjust.



You never know if it will be cable, electric servo, or vacuum anymore. My Ford uses electric and vacuum for the HVAC. Of course the engine makes no vacuum so you also need an electric powered vacuum pump.


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## Shari (Jun 2, 2011)

SolarAndWood said:
			
		

> Kind makes me want to go back to the days when the thing you turned had a cable connected to the thing you wanted to adjust.



You got that right!

Work on the truck has taken a back seat this morning.  Our riding mower has been in the shop awaiting parts.  We got a call the rider was done so we went out to get it.  Time for lunch now.  After lunch we have to put the hitch back on the rider so I can tote wood around the yard (finally!) but before toting wood around I have to get back to the truck issue.  Weather forecast is for high 80's Friday and Saturday - no fun riding around in a truck that is blasting heat when it's that hot outside!


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