AC stuck in defrost
#1
AC stuck in defrost
Just yesterday my A/C went to defrost yesterday and won’t blow out of the regular vents.
I’m not sure what it could be.
It started about a week /week and a half ago where under heavy acceleration it would go to defrost then drop back out of the regular vents
when it is blowing it is still cold air
At night this is that it looks like and would blow cold not sure if it’s apart of the blower settings
What could it be
where do I need to start looking
I’m not sure what it could be.
It started about a week /week and a half ago where under heavy acceleration it would go to defrost then drop back out of the regular vents
when it is blowing it is still cold air
At night this is that it looks like and would blow cold not sure if it’s apart of the blower settings
What could it be
where do I need to start looking
#4
RF Veteran
iTrader: (1)
The Vents, defrost, panel and floor, are operated by Vacuum "motors" inside the dash
Engine vacuum is stored in the Vacuum Reservoir in the engine bay, "black ball"
Defrost is the Default setting for these "motors" so No Vacuum = Defrost only
Low vacuum means switch to Defrost, engine acceleration has low vacuum................
There is a black plastic vacuum line that runs on top of the frame rail from "the ball" and into the cab thru firewall, passenger side under glove box, next to kick panel, you will see a black hose and white hose in side the cab
White hose changes to grey in engine bay, goes to heater hose bypass vale
Black hose is the vacuum from "the ball"
Inside the cab is usually fine
The problem is usually in engine bay
Find the black hose in engine bay, as said passenger side frame rail area, follow it and feel it, it can melt near exhaust pipes, or crack and leak
You can just splice it back together with regular rubber hose that fits snug on the plastic hose, no clamps are needed its VACUUM so sucks and pulls connections tighter, doesn't push them apart
Follow the hose to front of Ranger, and the Black Ball, looks like this: https://encrypted-tbn0.gstatic.com/i...oGyew&usqp=CAU
Located down low behind front bumper so you need to be under the front to see it, seen her with fender removed: https://www.explorerforum.com/forums...obe-jpg.39621/
Has TWO hoses attached, one goes to the firewall/cab, the other to the intake manifold on the engine
Either hose could be broken but.....................if the hose to the engine was broken then you should have a higher than normal idle, which you don't mention
As said most common reason for your symptom is broken black hose in engine bay
The black ***** do crack but not as common
Engine vacuum is stored in the Vacuum Reservoir in the engine bay, "black ball"
Defrost is the Default setting for these "motors" so No Vacuum = Defrost only
Low vacuum means switch to Defrost, engine acceleration has low vacuum................
There is a black plastic vacuum line that runs on top of the frame rail from "the ball" and into the cab thru firewall, passenger side under glove box, next to kick panel, you will see a black hose and white hose in side the cab
White hose changes to grey in engine bay, goes to heater hose bypass vale
Black hose is the vacuum from "the ball"
Inside the cab is usually fine
The problem is usually in engine bay
Find the black hose in engine bay, as said passenger side frame rail area, follow it and feel it, it can melt near exhaust pipes, or crack and leak
You can just splice it back together with regular rubber hose that fits snug on the plastic hose, no clamps are needed its VACUUM so sucks and pulls connections tighter, doesn't push them apart
Follow the hose to front of Ranger, and the Black Ball, looks like this: https://encrypted-tbn0.gstatic.com/i...oGyew&usqp=CAU
Located down low behind front bumper so you need to be under the front to see it, seen her with fender removed: https://www.explorerforum.com/forums...obe-jpg.39621/
Has TWO hoses attached, one goes to the firewall/cab, the other to the intake manifold on the engine
Either hose could be broken but.....................if the hose to the engine was broken then you should have a higher than normal idle, which you don't mention
As said most common reason for your symptom is broken black hose in engine bay
The black ***** do crack but not as common
#5
Once I got home from work I found the vacuum lines and the one from "the ball" to the heater core felt solid and fine no cracks and not loose.
However as I was running my finger over the one that runs to the intake from "the ball" is snap at the connection pictured below
is this an easy fix?
any idea on how to fix?
are parts readily available?
what part do I get?
can I drive with it like this?
However as I was running my finger over the one that runs to the intake from "the ball" is snap at the connection pictured below
is this an easy fix?
any idea on how to fix?
are parts readily available?
what part do I get?
can I drive with it like this?
#6
RF Veteran
iTrader: (1)
Good work you found the problem
Should be able to slide it back in and tape it for now, remember its a VACUUM hose so pulls together doesn't push apart
The device with the yellow mark "looks like" a Check Valve, which is needed to Hold Vacuum in the "ball" when accelerating
Its an inline one way valve for vacuum, so any auto parts store should have one, but your issue is the rubber fitting on the hose
There are many of these fittings on any newer vehicles, so wrecking yard stop, cut one off and use a short Splice rubber hose to connect the two ends
I think Dorman also sell those fittings
Should be able to slide it back in and tape it for now, remember its a VACUUM hose so pulls together doesn't push apart
The device with the yellow mark "looks like" a Check Valve, which is needed to Hold Vacuum in the "ball" when accelerating
Its an inline one way valve for vacuum, so any auto parts store should have one, but your issue is the rubber fitting on the hose
There are many of these fittings on any newer vehicles, so wrecking yard stop, cut one off and use a short Splice rubber hose to connect the two ends
I think Dorman also sell those fittings
#7
#9
RF Veteran
iTrader: (1)
You need to get some rubber hose that slides on tight to plastic hose
Take the broken piece into auto parts store
They will have correct size, and buy a few feet, if one hose broke there will be more, lol
They may also have the "rubber" ends, ask
Most car makers switched to these pre-made plastic hoses because they are CHEAP and can be pre-bent and color coded which makes hooking up the right hose to the right port easier on the assembly line
But the drawback is they get brittle over the years, but well after any warranty concerns, lol
Rubber hose can do the same but usually lasts longer
Point is there is nothing special about the hard plastic line, repair or replace any with rubber hose
Take the broken piece into auto parts store
They will have correct size, and buy a few feet, if one hose broke there will be more, lol
They may also have the "rubber" ends, ask
Most car makers switched to these pre-made plastic hoses because they are CHEAP and can be pre-bent and color coded which makes hooking up the right hose to the right port easier on the assembly line
But the drawback is they get brittle over the years, but well after any warranty concerns, lol
Rubber hose can do the same but usually lasts longer
Point is there is nothing special about the hard plastic line, repair or replace any with rubber hose
#11
RF Veteran
iTrader: (1)
You need it or vent will change to defrost when accelerating, but go back to previous setting(panel) when cruising or at idle, so your choice, and can live with that for a day or two
Intake manifold has say 18" of negative pressure at idle, when throttle first opens, or opens more, i.e. accelerating, it drops to 2" or lower, then will come back up to 18" once RPMs are consistant
Check valve holds vacuum in reservoir(BALL) at say 18" of negative pressure at all times
Check valve <|
18" vacuum----<|---17" or less vacuum, check valve closed
18' vacuum----<..|---19" vacuum or higher, check valve pulled open
The 18" in "ball" can go to 19" or more when higher vacuum pulls it open, but won't/shouldn't go lower than highest vacuum see in intake
Power brake booster has a check valve, its usually the 90deg elbow on the booster
So when you get into a vehicle and press down on brake pedal BEFORE starting the engine, you can feel you still have power assist, because booster still has vacuum, and should have even after months of not running the engine
Intake manifold has say 18" of negative pressure at idle, when throttle first opens, or opens more, i.e. accelerating, it drops to 2" or lower, then will come back up to 18" once RPMs are consistant
Check valve holds vacuum in reservoir(BALL) at say 18" of negative pressure at all times
Check valve <|
18" vacuum----<|---17" or less vacuum, check valve closed
18' vacuum----<..|---19" vacuum or higher, check valve pulled open
The 18" in "ball" can go to 19" or more when higher vacuum pulls it open, but won't/shouldn't go lower than highest vacuum see in intake
Power brake booster has a check valve, its usually the 90deg elbow on the booster
So when you get into a vehicle and press down on brake pedal BEFORE starting the engine, you can feel you still have power assist, because booster still has vacuum, and should have even after months of not running the engine
Last edited by RonD; 07-31-2022 at 11:43 AM.
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