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1986 Nissan 300ZX that blows hot air thur the defrost when I accelarate and wont blow cold thur dash all the time.I can hear a vacuum leak from under the hood only when decelrate how can I fix this?
Wiki User
∙ 15y ago
you're on thevright track. This problem comes from a cracked/loose vacuum hose, typically under the dash (driver's side), or sometimes under the hood. Only solution is to open both area up, get a flashlight and maybe an extension mirror and inspect all the hoses. Not expensive but time consuming!
Wiki User
∙ 15y ago
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How can you manually change from defrost to vent on a Nissan 300zx 1986?
If you have the electronic climate control system it most likely is a Vacuum Hose leak Start under the hood on Passenger side and replace all hoses from canister to under the dash this should help. With a Vacuum leak it defaults to defrost mode
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 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.
Air vents on your 2005 f-250 6.0 diesel blow only out defrost ports and not from vent or floor What is going on?
you have a vacuum leak. defrost is the default when a vacuum leak is present.
What is the can with vacuum lines attached in wheel well of your F150?
It is for vacuum storage. It keeps blower mode from switching to defrost when accelerating. The mode selection is vac controlled and will default to defrost when vac is lost or low. This stored vacuum keeps that from happening
Why is my defrost stuck on my blazer?
The air door under the Blazers dash could be stuck, or there could be a vacuum leak on the engine. The door opens and closes from vacuum, directing the air from heat to defrost.
Why would the ac change from dash vents to the defrost vents when accelerating?
Because you have a vacuum leak in the system or your vacuum canister is leaking. When you accelerate the vacuum from the engine will drop. That will cause your system to loose vacuum and the floor/defrost door will go to its neutral position. To keep the vacuum up you have a canister that will hold vacuum. It must be air tight.
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.
Why does a 2000 chev pu only have defrost?
The HVAC controls operate off of vacuum supplied from the engine. If the vacuum supply is cut off the system defaults to the defrost mode. My guess is the vacuum supply hose is disconnected/broken/cracked or pinched, start by checking under the hood and inspecting the vacuum lines.
2002 ford expedition max ac only blows out thru defrost vents?
Check for vacuum leak--either under dash or in engine compartment Check for bad vacuum motors under dash Defrost is the default position for this system There is a vacuum resovoir located behind your battery , it is for this condition. When you accel your engine doesn't produce vacuum due to the throttle plate being open so a resovoir is there to hold a vacuum reserve so that when there is low vacuum produced by the engine there will be reserve to hold the vacuum motor applied preventing the air from changing direction in your dash. When there is no vacuum the direction is at the defrost vents if you have a broken hose or no vacuum your ac would blow out the defrost all the time But since it happens when you accel it sounds like your vacuum resovoir is cracked thus not allowing it to hold a vacuum
Where is Vacuum leak under dash?
defrost or a/c compartment under the dash
Why does 2000 Buick Lesabre Custom Air Conditioner blow only through defrost vents?
The vacuum supply line from the engine is disconnected or broken. When the vacuum supply is cut off the system defaults to the defrost mode.
