88" Suburban Defroster does not work...? Advice

[OverRunWithSons]

when put on Defroster, it blows heat or air everywhere BUT underneath the window- where it is needed to defrost the window. Me, the wife is getting tired of this, as to defrost the windows, I have to be "cooked" in heat coming out everywhere else. Strange problem, and want to give my husband instructions on how to correct this if I can. It has been causing alot of fights . Thanks.

[bisquik65]

You need to check for vacume coming from the heater control valve to the heat/defroster door under the dash. I can get you pics of it tommorow eav. I am parting a 89 burb and the dash is all apart so it will be easy to see. I hope this will help you again,Erick

[OverRunWithSons]

Thank you, that was quick! He has to replace his 1st head gasket this week, the suburban is down, but this will be his next project when that is done. Any good advice about replacing a Head gasket for a Newbie - something the books may not tell you. I'll give him all this info. Thanks !

[bisquik65]

I always use fel-pro gaskets so you dont have to re-torque them after running a while. Its a major job to do. Just make sure you dont drop anything in the motor and while you are in there change both of them. If you do just one side now the other will go out in a week or two. I know you dont want to do it twice. Been there done that. Make sure you torque them in order too. follow the book and you will be o.k. And make sure you dont overtighten the valves too. I will post pics on the heater tommorow,Erick

[88Jimmy4x4]

Originally Posted by bisquik65

You need to check for vacume coming from the heater control valve to the heat/defroster door under the dash. I can get you pics of it tommorow eav. I am parting a 89 burb and the dash is all apart so it will be easy to see. I hope this will help you again,Erick

Could you post or email those pics to johnfbakerjr@yahoo.com

My heater wont blow to the floor, only blows out the dash vents and the defrost also blows out the dash vents and just a little out the glass area.

thanks

[bisquik65]

I have the whole heater box out of the dash so it will be easy to show you what to check. I will post pics in a little while.

[88Jimmy4x4]

Originally Posted by bisquik65

I have the whole heater box out of the dash so it will be easy to show you what to check. I will post pics in a little while.

Thank you very much

[cochino12]

Originally Posted by 88Jimmy4x4

Could you post or email those pics to johnfbakerjr@yahoo.com

My heater wont blow to the floor, only blows out the dash vents and the defrost also blows out the dash vents and just a little out the glass area.

thanks

really good info on this thread as well

[bisquik65]

Sorry about the late responce. Here you go... The 1st pic is the heater box assy. The 2nd is the defronts/floor vacume pod i am pointing to. Check this for vacume.if none then check to see if there is vacume going through the fire wll from the motor. If you do have vacume here the door is jammed(pic 3 ) . or the vacume pod itself is bad.

[bisquik65]

Here is the fresh air door and vacume pod. If there is no vacume here change the heater control to a/c and this one should open. If not the pod may be bad or the door is jammed.(ex .. a inkpen has fallen in the defroster vent) thats all it takes sometimes. If you need any further please post here i will try to help everyone,Thanks,Erick

[88Jimmy4x4]

Thanks for the pics and your help, I will check it out this weekend and see if I have vacuum first :p

[OverRunWithSons]

I am sending this link to my husband, thanks again !

[Bob Gervais]

I have a similar problem, although I can hear the vacuum when I switch the heater controls.

Also, there is very little heat coming out of any position. Both heater hoses are as hot as the radiator hoses, and the box inside is hot as well.

I replaced the heater core last year, and since then it's been like this.

I'm guessing the lukewarm heat is due to an outside air leak?

[bisquik65]

These vacume pods are a very common probler,the rubber in them will dry out and leak vacume,only opening half way, I would say thats the one. I am pointing to is the heater/defrost door. The one on top is probally the one,that opens to outside air. Check it out and let me know,I will try to help everyone here. Thank you all,Erick

[Bob Gervais]

I think that's most likely the problem, along with an outside air leak. I'll be taking the whole box back out this week, to attempt to repair the problem.

I did, however, find another issue with why my defroster wasn't getting any air. The vacuum line that goes to the little plastic ball was broken. I replaced it, and it now diverts to defrost. Well, with the cold air, it's more of a re-frost, but I'll get that squared away.