Why is the defrost not working on my GM Truck?

My airflow is stuck in the floor position no matter what setting is switched on the dash vent switch. I can’t get defrost or dash vent air to work. Fan settings do work. Also, there is no light coming on when the AC button and/or the recirculating buttons are pushed.

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 there a center console on a GMC Sierra?

This Sierra has auto a/c controls and no floor mounted center console. Of course the customer brought the truck in, knowing that I had to lay under the driver’s side of the dash and did not think to vacuum the floor board. I checked the codes and sure enough there was a code B0263 stored in the HVAC module.

Are there any problems with the power window on a Silverado?

Re: Driver Side Power Window problems. So has anybody figured out the mysterious 2007 Silverado drivers door window issue?

Why does air not blow out the dash vents?

The air won’t blow out the dash vents. It blows out the floor vent and the defroster vent, but it won’t change and blow out the dash vent. Any one know what I need to do to fix this problem?

What causes air vents to stay in defrost position?

If you have an older car then the defroster system is controlled by using vacuum supplied by the engine. Lift the hood and inspect the vacuum hose or tube that leads from the intake manifold to the passenger’s side firewall. The image below shows a typical line break which causes the vents to stay in the defrost position.

Can a GMC Envoy Air Conditioner blow out front vents?

Will not blow out front vents, only floor and defrost positions. Numerous tries to reset and will not work. Air conditioner won’t blow from dash vents but will from the back vents have tested the blower motor and works great. And checked cables but nothing else is working

The air won’t blow out the dash vents. It blows out the floor vent and the defroster vent, but it won’t change and blow out the dash vent. Any one know what I need to do to fix this problem?

Can a defrost fan blow to the floor?

Fan Only Blows Defrost, Won’t Change To Floor Or Vent. I discovered today that I only receive air through the defrost vents. tried to change it to the floor or the dash vents, no deal.

What kind of defrost does a 1983 Chevy K10 have?

I have a 1983 Chevy k10 with a 350 engine. My defrost doesn’t seem to work right it just seems to blow everywhere and not very much at that either. The vent and heater settings work great but defrost doesn’t.

What to do when air blows out of defroster vents?

Assuming that your actuator has failed in the most common position, blowing out of the defroster vents only, you should not have to do anything other than installing the actuator motor. No indexing of the door shafts to the cam/cog or recalibration of the actuator motors.

Fan Only Blows Defrost, Won’t Change To Floor Or Vent. I discovered today that I only receive air through the defrost vents. tried to change it to the floor or the dash vents, no deal.

How do you defrost a GMC truck floor?

1. Remove the floor air outlet duct extension (1) from the floor duct (2). 2. Remove the center console. 3. Remove the screws from the center console duct. 4. Remove the center console duct. 1. Remove the floor air outlet duct extension (1) from the floor duct (2).

Where is the defroster door on an air conditioner?

The doors control the destination of airflow out of the Dash vents, Defrost vents, Heater vents, etc. Assuming you have factory A/C, there is a small vacuum operated rectangular door (called the Mode Door) located above the center floor hump directly in between the Heater/AC housing and the Defroster ducts.

Why does air come out of the defroster vent only?

At light throttle or when you were on level ground, it was ok. Start up a hill or give it gas to pass someone and the AC would start blowing out of the defroster vents. It still used vacuum. Had to have it fixed one time. One vacuum line from the rear of the intake runs to the control valve under the dash. It must be different from the trucks.

Where are the vents on my GMC Sierra?

No output on dash face vents or defrost vents but floor works ok. I have tried the pulling the fuses both under hood and left of dash but that did not fix my problem.

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.

Is there issue with auto climate control not changing from vent to vent?

Has anyone had an issue with the auto climate control not changing from vent to vent? Re: Fan Only Blows Defrost, Won’t Change To Floor Or Vent. Pull the negative battery cable and re-install, making sure it is very tight (also check the positive to make sure it is tight). See if this fixes the problem.

Where is the actuator motor on a GMC Sierra?

The goal is to leave the cam/cog in place on the end of the heater-a/c case and to remove the actuator motor only. The old assembly on the left and the new one on the right. Taking the new actuator motor and installing it on the old cam/cog.

How does the climate system control the defroster?

The climate system is responsible for controlling the position of the defroster actuator which is connected to the air position door in the heater plenum. This actuator controls defrost, middle and lower air vents. When it fails it can do so in the defrost position and must be replaced.

What to do if your defroster wont blow out top vents?

If you need further assistance with defroster not working on top vents, then seek out a professional, such as one from Your Mechanic, to help you. The statements expressed above are only for informational purposes and should be independently verified.

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.

Why is the a / C light on on my GM Truck?

If the a/c button is pressed in but fan selector is off the amber a/c light will be on sometimes or just flicker. I checked this part at LMC and it shows the ’95 using a control assembly that is unique to just the 95 models. It looks like the same one as the 96 to 99 models. Good luck!

Where is the mode actuator on a 1995 GMC c1500?

This 1995 GMC C1500 came in with the complaint that the air would blow from everywhere except the front vents. In using the controls, the air flow would adjust from the defrost to the floor. All other functions were okay as well. The mode actuator is located under the driver’s side of the dash, above the gas pedal.

What should I do if my GM fan won’t turn on?

Pull the negative battery cable and re-install, making sure it is very tight (also check the positive to make sure it is tight). 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.

Is the GMC heater fan control switch good for?

WARNING: This product can expose you to chemicals including Lead and Lead Compounds, which are known to the State of California to cause cancer, and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov. This item is backed by our limited lifetime warranty.

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.

What kind of air flow does a GMC Sierra have?

9 people found this helpful. Click on the print – it will become full screen. Right click on the full size and copy it to your folder. Then click on that “Best answer” button. 12 people found this helpful. 1995 Chevy 5.7 lye when in AC circulation mode no increase in air flow.

Why does the AC only blow out the defrost vent?

Click to expand… Mode door actuator for where it’s blowing. Blend door actuator for hot/cold. These are more likely culprits than the control module in the front. The rear control module being bad is more common. How can I post this message for help?

Why does air come out of the dash vents?

If system (fan switch) is off and I just have it on vent, the outside air mostly blows at your feet. Sometimes it will come out of the dash vents. If the a/c button is pressed in but fan selector is off the amber a/c light will be on sometimes or just flicker.

Where is the actuator on the GM P / N?

Here is what the actuator that controls which vent the air blows out of looks like (click for bigger): GM p/n 52473356. I picked up a new one from GM Parts Direct for $53. To answer my own question, this is where the actuator is located on the driver’s side to the right of the steering wheel (click for bigger):

How to change the mode actuator on a 2003 Chevy Silverado?

This repair of course should be generally the same for 2003 through 2007 Classic series trucks and suvs. Remember to preset the controls to the split defrost / floor position before removing the old actuator. If needed, use a small screwdriver or the edge of a quarter to rotate the actuator into the correct position.

Can a GM AC Control head be reset?

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. Honestly, don’t know if your control head has a built in recal feature, but a cheap way to find out.

What kind of climate controls does a GMC have?

You are currently viewing GMC.com (United States). Close this window to stay here or choose another country to see vehicles and services specific to your location. Your GMC is equipped with climate controls that allow you and your passengers to stay comfortable – whether you’re braving the heat of summer or the chill of winter.

Why does my Mazda Protege heater only blow out front vents?

Eighth generation of the Mazda Protege. Heater only blowing out front vents, no heat to feet or defrost. Why? Heater working but only blows out front vents. No heat to feet or defrost.

Why does my a / C turn on when I Turn on the defrost?

Nothing, that is how the defrost works. When you turn on the defrost the A/C turns on automaticaly. If you mean that the air blows out of your “vent” air ducts when you turn on the A/C then you may have something stuck in your air duct plentum or a air duct plentum door is not working.

Where is the defroster located in an air conditioner?

The defroster is part of the heater and air conditioner system which is housed inside of the heater plenum. The vent control system for the defroster in integrated into the operation of all temperature controls and uses forced air provided by the blower motor.

How does the air vent work on a defroster?

The vent control system for the defroster in integrated into the operation of all temperature controls and uses forced air provided by the blower motor. On newer cars the vent direction and temperature controls are operated by a series of 3 or 4 electrical actuator motors which are adjusted by the climate control module.

What should I do if my rear defroster is blowing?

If there is no power to the switch, then check the fuses and see if any of them are blown. The rear defroster has a blend door that opens and closes that is electronically. If the fuse is blown, either the switch has failed or the blend door motor has failed.

What to do if your car’s AC is not working?

Check the vacuum lines to the engine and see if any of them are broken, has a hole, or is disconnected. Check the vacuum hose on the blend door and see if it has came off or broke. For the rear defroster, check the switch to the defroster and make sure that it has power to it and power coming out.

When to use defroster on Dodge Ram 2500?

The defroster is the single most important function after the engine starts during cool, foggy weather, cold, dry weather, freezing rain, snow, and several other conditions not mentioned- it is stupid and irresponsible for dodge not to address this problem with a recall.

What to do if your car heater is blowing out cold air?

Run the engine until the fan kicks in. Once your fan has come on, look around the radiator for a bleed port or bleed screw. This is something that can be turned with a screwdriver. Once you turn it anti-clockwise, you should hear a hiss; this is the air being released. 4. Are the Heater or Heater Controls Broken?

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