1999 LeSabre air blows but no heat, please help!

[huynh]

Dear all,
I have a 1999 Buick LeSabre with 120K miles.
When I turn on the defrost or heat in the car at 80-85 degree (rarely turn that high), the air blows out but a lot colder. Also, when I switch from the defrost to dash or feet, the air keeps blowing to the windshield.
Any idea to help would be greatly appreciated.
Huynh

[FishFind]

check switch?? maybe the vacuum lines for the blower??

[GSGregg]

Sorry, I'm not familiar with your specific system (especially not knowing whether you have manual or automatic climate control), but my bet would be vacuum. Check for a small-diameter plastic tube (probably black) coming off the engine and disappearing into the firewall; on a 13-year-old car, the plastic could have dried out and broken or its rubber connector likewise. Then, there's always the possibility that someone just left it disconnected.....

[huynh]

Thank you, all!

I am going to check all those possibilities. The car has automatic climate control.

I have searched and found that the thermostat is also another possible cause. Recently, the car has had a leak in the intake manifold gaskets. The mechanic changed the thermostat too. I do not know if I should replace the thermostat, but I will try and see if it helps.

[Tech II]

Do you have a temp gage?

When the car is at normal operating temp, feel both heater core hoses...are they both hot, both cool, or one hot and one cool?

Set your auto temp on 90, do you have heat now?

You may have a vacuum solenoid box.....if yes, I think the source vac is a purple line....check for vacuum....