Hello, Can someone help me!!

I have a-99 Blazer that all of a sudden started to blow very hot air and it have no effect if I turn down the temp to 66F. It just pumps in hot air.
Even if I turn off the A/C the hot air is still comming.

The aircondition is working the hoses under the hood is cold.

/S

Since you mentioned 66F I will assume that your Blazer is equipped with climate control. Although I have never seen one or had the fortune or misfortune to work on one I will endeavor to steer you in a proper direction. As with any A/C system, it utilizes the same blower as the heating system. It sounds as if the blending door is remaining open which is permitting the forced air to go across the heater core. In other GM climate controls, i.e. Cadillac, that I have worked on, there are two doors that are synchronized to open and close opposite each other for the blending of air to maintain the temperature that you select. In short, it sounds as if they are not operating and that the door to the heater core is open and the door to the evaporator is closed. Hope this helps.

My 2000 Jimmy SLE has basically the same problem, but I don't have climate control. I have 50° F air blowing from the vents with the air on, and 100° F blowing out if I turn the air off, even if the outside air is 60° F. My Stealer blames it on the intake for the blower fan being too close to the exhaust manifold. Does the same solution apply? I've always suspected that a door was stuck.

Rick, 50F air is not bad, however, I am assuming that that is the case even if the ambient is 90F at 90% humidity. R134 is not very efficient in an AC system, in fact, my system in my '93 needs a recharge and I will recover the R12 and replace the compressor, orifice tube and the accumulator and recharge with R12 only because it is more efficient. However, in your situation, in the heater box are the two doors for blending. In a manual temp control for a 2000, if I remember correctly, it is electonic. When you turn the tempcontrol, it varies the two doors depending on the position of the control. These doors have foam around them to seal the air flow when closed. This foam could be off. The other solution is either the controller or the actuators. Best I can do without seeing the vehicle. What you can do is to run the defroster and vary the control. The temp should swing from hot to cold. If it does, I would assume that everything is functioning as it should and the foam would be the culprit. Good luck!

Hello, Can someone help me!!

I have a-99 Blazer that all of a sudden started to blow very hot air and it have no effect if I turn down the temp to 66F. It just pumps in hot air.
Even if I turn off the A/C the hot air is still comming.

The aircondition is working the hoses under the hood is cold.

/S

there is a plate that directs the air through the heater core that is malfunctioning.

Thanks!
I will take a look at the blending door.

Is the door controlled by vacuum or electrical motors?

Best Regards,
/S

Good question, I honestly don't know. The blending door seems to be stuck open.

Take a poke around.

You should be able to access the blending door if you remove the glove box. The lever is below along with the actuator. Did you do what I posted previously to determine if the doors are moving at all? As I said previously, it could be the foam. Hope that it isn't for the actuator is easier to get but it will cost more than foam.