Suburban heater issues

[Tilar]

I have a 96 Suburban and for some reason the heater will just start blowing cold air. I can turn the temperature control knob to cold and then hot and it will start blowing hot air again. Sometimes it will stay hot and sometimes I have to turn that knob a dozen time or more to get it to keep the temp up.

Anyone have any idea where to start looking? In my mind it seems like the knob itself but I had the guy at the parts store mention a heater door motor or something like that. The rear heat doesn't seem to be affected.

[268RTs4ME]

First thing to do is check all vacumn line, the opening and closing of the doors is controlled by vacumn, make sure there are no vacumn lines off under the hood . also start up and inside car look under dash and see if you see a vacum line off or here a vacum leak. also could be you control itself.

[Cooter]

Those vehicles have what's called Heater/ A/C "Blend" doors that are computer controlled by the body control module, and are Electrically controlled....What we usually see are the blend door actuators stripped at the little motors, OR the actual PLASTIC blend door inside the HVAC unit warped and sticking causing the actuator to strip.....this is an expensive repair if this is it, as one is on the back side of the HVAC unit and the entire dash has to come out to get at it..However, I would make sure it was full of Coolant and that the cooling system isn't Clogged up with old coolant and crap...You would not believe what a cooling system looks like inside after 10 years with the same coolant in the radiator...

[dpm68]

...You would not believe what a cooling system looks like inside after 10 years with the same coolant in the radiator...

I heard that.

[moparstuart]

 not sure this is your problem  , but i sell everyone of those heaters a/c controlls as soon as we get them in the salvage yard . They go bad alot   

[Tilar]

Those vehicles have what's called Heater/ A/C "Blend" doors that are computer controlled by the body control module, and are Electrically controlled....What we usually see are the blend door actuators stripped at the little motors, OR the actual PLASTIC blend door inside the HVAC unit warped and sticking causing the actuator to strip.....this is an expensive repair if this is it, as one is on the back side of the HVAC unit and the entire dash has to come out to get at it..However, I would make sure it was full of Coolant and that the cooling system isn't Clogged up with old coolant and crap...You would not believe what a cooling system looks like inside after 10 years with the same coolant in the radiator...

It's not low on antifreeze. I keep a close eye on all my levels since it just turned over 190,000 miles and it has no leaks of any kind.  Plus the rear heat doesn't seem to be affected by it. I drained the system when I got it a couple years ago to change the water pump and what came out didn't look any worse than the new that I put in. And I don't think it has any vacuum controls on this one. 

I think the blend door actuator is what the parts man was trying to sell me. It just seems odd that I can wiggle the temp control and it heats right back up.  If the door actuator was the problem, would it start out heating and then turn cold all at once?

not sure this is your problem  , but i sell everyone of those heaters a/c controlls as soon as we get them in the salvage yard . They go bad alot   

In my mind I'm thinking that is what the problem is.  The local carquest store can't get them so it's either a dealer item or a salvage yard. Since you say you sell every one of them, I assume you don't have any right now?  If it turns out that is what it is and you have one in the yard and can ship it, I'd just as soon buy one from you as anyone.

[moparstuart]

 What state are you in ? and city  , I'll try and find one for you local to you so you can return it if it's not the problem  ?
also does it have a/c , and rear defrost button  ?

 they have little push tabs on each end of them that clip in that usually break off to .  I usually gorilla glue the tabs back on and that works well if its not pulled in and out several times .

[Tilar]

Thanks. The closest town that has a salvage yard would be Mansfield Ohio. Yeah, It has A/C and rear defrost.

[moparstuart]

 I dont know ohio well so i will just post all the ones  i found in ohio ,  you get to do the rest  LOL  All these yards show on the locator to have the correct controlls in stock


  R and B Auto Salvage Inc. USA-OH(Middletown) Request_Quote 513-423-9417

  Allgeier Auto Parts USA-OH(Cincinnati) Request_Quote 513-353-3377 / 800-745-3378

   C & M Auto Salvage USA-OH(New-Springfield) Request_Quote 1-330-549-2856
   
    National Auto and Truck Salvage USA-OH(Wapakoneta) Request_Quote 419-645-4108

    Duck Creek Auto Parts USA-OH(Cincinnati) Request_Quote 513-321-9278

     Hamer Rd. Auto Salvage USA-OH(Georgetown) Request_Quote 937-378-3895

     Marshalls Auto Parts, Inc. USA-OH(Circleville) Request_Quote 1-800-333-2104

    Fox Auto Parts USA-OH(Malvern) Request_Quote 1-800-228-6159
     
   

[moparstuart]

Buckeye Auto Parts of Columbus, Inc. USA-OH(Columbus) Request_Quote 1-800-358-1234

Youngstown Auto Wrecking LLC USA-OH(Youngstown) Request_Quote 1-330-743-1492

Art's Parts USA-OH(Middletown) Request_Quote 1-800-404-7133

Lake Auto Recycling, Inc. USA-OH(Akron) E-mail 1-866-753-2287

Carthage Auto Parts USA-OH(Cincinnati) Request_Quote 513-761-4887 / 800-437-5715

[Tilar]

Holy crap that was fast.  Thanks. I can go from there.

[moparstuart]

any of them close i hope  ??

[Tilar]

Looks like the closest one is Columbus, probably 60 miles away. I'm thinking about making a run to the Dayton area to look at a car this weekend and can go by there if I do.

[Tilar]

not sure this is your problem  , but i sell everyone of those heaters a/c controlls as soon as we get them in the salvage yard . They go bad alot   

Thanks Stuart, You nailed it right on the money. Nobody around here had a used one so I finally bought a new one off of ebay. The local Chevy dealer wanted close to $300 for one and the guy on ebay had new ones for $112 and change including freight. After I got this one I did a little research and you can get them right from Ac Delco but this guy on ebay was as cheap as I could find.

[moparstuart]

    no problem like I said we sell alot of them so figured that was your problem