so i went to use my heat this morning cuz it was a little chilly out. I put the heat on defroster and air came out of every single vent. I moved the control to floor and defroster, no change, air still comes out of every vent. Any idea what could be the issue?

 

Same thing with my 99' Blazer.

 

anyone?

 

AC vent blendoor could be stuck causing the air to come out of all vents. only thing i can think of

 

As i understand and if I am wrong please correct me... it takes vacuum to hold the blend door in the heat or def. position. When it loses vac the door returns to vent postion.
Does anyone know where the vacuum hose enters the under-dash area or where it connects to the heat/AC controls?
I'm looking at the 1995-04 S10 Haynes manual (they suck) and it shows a picture of an older S10 or at least it doesn't look like my 1999 Jimmy heater/AC selector that has climacontrol.
I think the OP and my blend door isn't moving at all when the selector is changed from vent to floor or def.
Any idea how or where to access the blend door? If it is 'stuck' maybe I can free it up.
I'm thinking we all have the same malfunction.



!!!! I just heard on TV news a woman had put her kid, a baby, a human child in a cardboard box and with the kid in the box she put it on the roof rack of her vehicle then tied it down with coat hangers and got on the interstate for a road trip! W-T-F!!!!!!

 

My 1999 Jimmy also has the problem where regaurdless where the selector is set air will blow only out of the vents .
A GM mechanic I know said "there is an acuator motor under there that probably needs replaced, happens all the time."
Also, my drivers side rear caliper is sticking and heating up the rotor. He said the parts stores sell a
"loaded caliper with the bracket and everything" .
I may as well have him install pads too.
I live in northern IL. and it gets perdy cold here so I'm going to try:
Mobil 1 5-20w oil and a
FRAM Extended Guard pn XG3980 oil filter. It cost a little more and felt heavier than the $1.87 plainjane oil filter.
What'dya think?

Thanks

 

Sounds like you could have a vacuum problem to the HVAC control head. Do you have manual or automatic climate control?

 

manual

 

when you lose vacuum to the diverters it goes to floor and defrost, not the vents. I know this cause my 97 bravada had the same issue. sounds to me like something is getting stuck.

 

Could be a combination. Diagnosis starts with determining if the proper supply is at the HVAC control head. Then branch out from there.

This should answer a lot of questions:


With the design of the '01+ HVAC system, they added a slave door to the mode door. This could allow air to circulate out the I/P vents when there is a loss of vacuum to the HVAC control head.