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Q: Heater control stuck on defrost whats problem?
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Why is heater control stuck on blend Wont kick into defrost or heater?

Check behind the heat control panel to be sure that the vacuum hoses are all securely plugged into the control switch. As a safety measure on all cars, if you lose vacuum altogether, the default position for air direction is on defrost, so you can always see out of the windshield. Jake McCahn

Why your defroster suddenly stopped?

The water is not circulating through the heater core or you have a control problem. If the heater is putting out heat then it is probably a control problem. If no heat then - water pump out, low on coolant, or maybe the therostat is stuck open.

Car heater and defrost only blow cold air?

Thermostat stuck open, if older car possibly clogged heater core- when run at oper temp the hoses going into/out of heater core be sure one is very hot - start with thermostat $$$ cheap & easier than a heater core problem!

Defrost on windstar not working what is part needs to be replaced?

Where the air blows out control are vacuum operated.A more common problem is when the air is stuck on defrost only.The cause is essentially the same, so check out the "Related Question" below for where to go next

Why would the heater switch not change off the defrost position on a 96 Cherokee?

1. heat control linkage disconnected or broken or vacuum source problems(low vaccum source or broken vacuum lines) 2. heater unit doors stuck or non functioning heater door actuators

Freezer not freezing in my side by side?

If you have already tried adjusting the temp controls the problem is likely a defrost control that is stuck in the "On" position. It is operated by the same timer as the ice maker. This is not a do-it-yourself repair.

What does the heater valve do?

The heater control valve is used to shut off hot coolant from entering the core when the heater is in the off position. A heater control valve can be actuated by either a vacuum line or a cable from the vacuum heater control valve to the heater core. This hose should be warm; if not the heater control valve is stuck and needs to be replaced

What is the problem with my Defroster blows cold air but the vent and heater blows nothing in your 1999 Ford Taurus?

Could this be 2 separate problems?Stuck in defrost modeNo heatSee "Related Questions" below for more about both

What symptoms means your 2004 Toyota Sienna needs a new thermostat?

Little or no heat from heater/defrost if t-stat is stuck open. Engine overheats if t-stat is stuck closed.


It sounds like your air flow diverter is stuck on defrost. Basically it is a little door that diverts the air fom vent to defrost to feet. It could be either the heater control valve, or te temperature selecter cable is broke.

How do you figure out why the heater and blower work but the ac and defroster do not?

The HVAC doors that control the airflow are activated by small vacuum motors. The system is designed to fail safe; this means that the system will fail in full defrost mode. So, knowing this and the fact that you have heater but no A/C or defrost you should assume the system has a failed control head (the part that you select functions with with button or lever). Or the doors are stuck due to an warped duct system (usually high heat related).

In a 99 Windstar LX the heater blower is stuck in the windshield position I move the selector but nothing changes how do you fix this problem?

Could be a vacuum leak "defrost" is the default position of the system Check vacuum lines and motors under the dash

Why would heat be cold in 98 ford van?

Thermostat is missing or stuck open, coolant level is low, heater core is plugged or heater control valve is stuck closed.

2002 Oldsmobile Alero only blows warm air when heater is on and only when its on defrost?

Could be,a stuck open thermostat,low on coolant,plugged heater core,faulty temp blend door actuator,

Why does heat come out of defrost vent at same time ac is on blowing cold air on 93 wrangler yj?

Your air mix door is stuck, follow the cable from the temp control to the heater/ac unit and see if the flapper is moving, if not the door itself may be stuck or broken and you'll need to get in there and replace it.

Why does your truck blow heat even in ac mode?

The heater control valve is stuck open.

I have an 03 Chrysler town and country and the heater is stuck on when you turn the climate control off it blows faster out of floor heater stuck on?

The blower resistor power module has failed. It is behind the glove box.

What could cause a sedona to have no heat?

There are several possible causes. A thermostat stuck open A heater control valve stuck closed A malfunctioning blend air door (located in the heater box) Low coolant level Malfunctioning heater controls

What are the proper steps needed to troubleshoot and resolve a climate control problem where the heater is blowing cold air in a 1995 Buick Roadmaster?

Thermostat stuck open or heater core clogged. Bad radiator cap or small hole in cooling system.

Why does your blazer blow cold air?

Thermostat stuck open. Heater core clogged. Heater temperture control valve defective. Low on coolant.

What could cause a heater to not function properly in a 1997 Grand Prix?

not function how. No heat, not enough, no fan doesnt' change heat to defrost? All different answers. No heat, not enough, May just be low on coolant. Therostat stuck open. No fan, fuse, ground, switch. Doesn't change heat/defrost? Cable, control, some switches are vacumn operated.

My heater blows very little warm air on my 1996 doge 1500 truck?

Thermostat stuck open, heater core clogged, or the heater temperture control vlalve is defective.

You Have 94 Caprice Classic Da Heat Won't get hot It will get a lil warm but that it's you Put a heater element in it so what's da problem?

By heater element I am assuming you mean a heater core. If that is the case then you have one of two problems. Either the thermostat is stuck open and needs replacing or the heater temperature control valve is defective.

Why does the AC Heater NOT blowing out the vent on a 2004 Sebring?

If it's stuck in defrost your battery died and messed up the computer. Disconnect battery for 5 or more min. It worked on my 96

Why is your heater blowing constant hot air even when set to cold?

Heater control valve stuck open. Possible blend air door failure.