Vent question not AC

[Alex Brooks]

Ok so my mode switch works. ac works and blows cold.
But went I just want to bring in out side with the vent set to cold hot air still comes out of the vents in the car.

I check to see if the heater control valve close and it does close on max ac.
Is my temp control knob dead ?

[CriticalB]

Is your blend door opening/closing when you adjust the temp knob? you might be able to see if the door is actuating from the passenger footwell. Even if the heater core isn't getting hot, maybe the air is still bypassing the evaporator.

[eight8toy]

I just tore apart my HVAC to replace my evaporator and I don't think the air ever bypasses the evap to my knowledge. Would just blow past it on its way to the heater core for hot air. Someone correct me if I'm wrong though.

I would agree your blend door may not be working properly with the temp control knob. Should be able to hear it move back and forth in the passenger foot well when adjusting it. To be honest, before I fixed my AC, even when I had the cold temp set to vent, the air still came through fairly warm, at least warmer than outside temps. Man the car was miserable to drive when it was hot out!

[dn010]

I just tore apart my HVAC to replace my evaporator and I don't think the air ever bypasses the evap to my knowledge. Would just blow past it on its way to the heater core for hot air. Someone correct me if I'm wrong though.

I would agree your blend door may not be working properly with the temp control knob. Should be able to hear it move back and forth in the passenger foot well when adjusting it. To be honest, before I fixed my AC, even when I had the cold temp set to vent, the air still came through fairly warm, at least warmer than outside temps. Man the car was miserable to drive when it was hot out!

+1. Check the cable to the blend flap.

[Alex Brooks]

+1. Check the cable to the blend flap.

Ok I will check that today are the blend motors vaccum powered ?
Thank you for the replies.

[dn010]

The door that is controlled by the temp knob uses a cable. The rest are vacuum.

[Alex Brooks]

The door that is controlled by the temp knob uses a cable. The rest are vacuum.

So I should be able to hear it move with the car running ?

[dn010]

If you're asking about the temp knob I think it would be difficult to tell if the cable is actually working without looking at the ends and making sure it's connected and moving - you won't hear the actual door, you might notice a difference in air sound from full hot to full cold though when the fan is running. If you use the mode switch you should hear things opening and closing. There are not that many things to check and most can be seen just by looking under the dash. My control cable is light blue in color so it is easy to identify, I'm not sure if all original cables are like that or not but if so, that is what you're looking for as far as the temp control issue.

[eight8toy]

Mine was light blue as well.

Make sure to turn the engine on just to build vacuum in the system so all the doors and stuff are "charged". The blend door won't need vacuum though to work...

I would think you would be able to hear faintly the door moving when you adjust the temp control knob but your ear would have to be right next to the HVAC box I guess. The knob would probably be much easier to twist if the cable is indeed not connected anymore. Is your temp knob turning freely or do you feel some normal resistance while adjusting it?

[Alex Brooks]

Mine was light blue as well.

Make sure to turn the engine on just to build vacuum in the system so all the doors and stuff are "charged". The blend door won't need vacuum though to work...

I would think you would be able to hear faintly the door moving when you adjust the temp control knob but your ear would have to be right next to the HVAC box I guess. The knob would probably be much easier to twist if the cable is indeed not connected anymore. Is your temp knob turning freely or do you feel some normal resistance while adjusting it?

The knob I feel is somewhat hard to turn but I can hear it moving something. Mine is also light blue. I’m quite perplexed why I keep getting warm air. It if I turn the air on the air gets cold. But like this morning it’s 50 degrees I would like to just bring in some fresh air.