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Is the heater ac vent on my 92 delta 88 ran by a vacuum line my air is coming out the defrost and wont change to vent?
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Why would the heater switch not change off of defrost position on a 2000 S10?
You have a vacuum line disconnected probably under the hood. The HVAC controls are operated by vacuum and when there is no vacuum it system goes into defrost mode.
Why does air start coming out of the vents and defrost and then stop coming after a while when you can still hear the heater fan motor running on 1999 Chevy S-10?
You have a vacuum leak somewhere. Check under the hood for a disconnected or broken vacuum line.
Why wont your heater change from feet to defrost but blows out hot air still?
most likely your heater controls run via vacuum lines. cracked or broken lines could cause this.
Why does heater default to defrost on a 2003 jeep wrangler?
It's a vacuum leak somewhere in the system. There are several vacuum lines that operate the blend doors on the system. If there is a leak where the system will not hold vacuum, it will default to defrost automatically.
Why doesn't your heater switch from defrost to heat on a 97 wrangler?
you probabally have a vacuum hose disconnected
Does the 1986 e150 ford van have a problem with your heater air condition controls I cant change from floor or main only have defrost?
The various functions are controlled by engine vacuum,defrost being the default without vacuum. Look far a damaged or loose vacuum line starting from the function switch,through the reservoir,to the engine vacuum port.
Why heat blows out vents only not defrost or floor?
Most likely a bad or disconnected vacuum hose to the defrost/floor selector in the heater ducting.
Why does heater go to defrost by it self and back to the floor?
My guess is that you have a vacuum supply problem. Most HVAC systems operate off of a vacuum and if the vacuum supply is cut off the system goes to defrost by default, your most important function. Check under the hood for a cracked or pinched vacuum hose.
How can you change the air vent from your vent to defrost on a '77 Dodge Power Wagon with AC?
Make sure you have vacuum coming into the cab from the engine. There may be something wrong with the switches.
Heater and ac only blows on defrost?
Many cars use engine vacuum to operate HVAC controls. If vacuum is cut off the system defaults to the defrost mode. Check the HVAC vacuum supply hose under the hood leading from the engine. It may be disconnected or damaged.
What could be causing your heater controls not to change from vent to defrost etc?
Don't know what vehicle you have but most HVAC controls operate from a vacuum supply from the engine. I would start with checking the vacuum supply connections under the hood. They could be cracked or disconnected.
Why would the heater switch not change off the defrost position on a 1993 Dodge Caravan?
There is a 1 way vacuum check valve in the eng compartment it is either disconnected or the valve is bad. comes of of the brake booster,thin vacuum line that goes into the vehical
