What to do when air blows out of defrost?

Try resetting the HVAC system. I had a similar problem on my 2002 Avalanche. Here’s what I did, and it worked for me. Turn the HVAC system off (turn the blower motor switch to off), and the radio off. Then turn off the truck, and disconnect the battery for 5 minutes. Reconnect the battery, then turn the ignition on, but do not start.

Why does my Astros heat only blow through defrost?

On the Astros when the heat only blows through defrost and floor it’s due to a broken vacuum line. No it isn’t, it’s all electronic. Jasen wrote: I believe the heater control system in these trucks is vacuum operated like my 97 Astro. On the Astros when the heat only blows through defrost and floor it’s due to a broken vacuum line.

Why does heat only blow through defrost and floor?

What to do if your truck fan only blows defrost?

Honestly, don’t know if your control head has a built in recal feature, but a cheap way to find out. Re: Fan Only Blows Defrost, Won’t Change To Floor Or Vent. When you reattach the battery and crank the truck dont touch anything for five minutes. Then shut the truck off, crank it and see if its fixed.

Why is air only blowing out of defrost and floor?

Jasen wrote: I believe the heater control system in these trucks is vacuum operated like my 97 Astro. On the Astros when the heat only blows through defrost and floor it’s due to a broken vacuum line. No it isn’t, it’s all electronic.

Can a climate control fan only blow defrost?

SilveradoSierra.com • Fan Only Blows Defrost, Won’t Change To Floor Or Vent. : Climate Control Fan Only Blows Defrost, Won’t Change To Floor Or Vent.

What to do about HVAC issues on a Chevy Silverado?

If you’ve noticed the control issues happening after disconnecting the battery or having repair work done, then the quickest fix is to recalibrate the HVAC. Turn the ignition off. Find the three HVAC fuses; Two are under the hood and one is in the cab fuse box.

Why does my Chevy Silverado blow hot air on one side?

This article applies to the Chevrolet Silverado (1999-Present). Does your Silverado blow hot air on one side and cold air on the other? If you have dual zone controls you may have run into this problem before. There is a way to fix this if you’re patient and willing to troubleshoot your way through it.

Why are the vents on my GMC Sierra stuck?

The most common symptom of course is lack of control over the vent output position and normally it will be stuck in the defroster only position. If it is not currently stuck in the defroster position but you are changing the actuator anyways. make sure that you set the vent position to defrost before starting this procedure. You will see why later.

Where does the air come from in a GMC Sierra?

This 2005 GMC Sierra came in with the complaint that the air will only flow from the defroster vents, regardless of where it is commanded to. This Sierra has auto a/c controls and no floor mounted center console.

Is the Astro fan only blows defrost?

Re: Fan Only Blows Defrost, Won’t Change To Floor Or Vent. Yea the problem with them astro’s is the way the damn motor is crammed into the dog house with the heat it destroys the hard plastic vacume line . I have had 5 of them and every one had this problem until you change them out with rubber lines .

Why is my HVAC not working on my Chevy Silverado?

Pull and reinsert the fuses for the HVAC before starting the truck. If this didn’t work for you try Step 2. If it seems like one side is stuck at one temperature only, it could mean the blend door actuator is no longer working. The actuator turns a door to switch between warm and cold air, but there are multiple actuators in your truck.

What to do if your GM fan won’t defrost?

See if this fixes the problem. Many of GM’s AC control heads have a built in reset feature that when power is removed and then applied it will go through a cycle that activates all the vent doors and mode doors. It’s worth a try.

What happens when the fan only blows defrost?

Re: Fan Only Blows Defrost, Won’t Change To Floor Or Vent. When you reattach the battery and crank the truck dont touch anything for five minutes. Then shut the truck off, crank it and see if its fixed. Not touching anything lets it go through its relearn process. Re: Fan Only Blows Defrost, Won’t Change To Floor Or Vent.