Weird A/C problem

Monkeyman · 06-10-2005, 06:25 AM

I have a '96 4x4 Jimmy (4.3, auto). When I turn my A/C on and "push" the motor at all (up a hill, from a start, etc), the air tends to go from the dash vents to the defroster vent. After about 30-45 seconds, it will revert back to where it's supposed to be. This also happens at other times but not as often. It doesn't matter if I have the selector on max A/C or regular A/C. It doesn't seem to do it on any other selection (vent, heat, etc).

Anybody have any ideas? It's not keeping me from driving (mostly a 60 mile round trip to work) but it's annoying as hell.

Dave

ras2002gt · 07-01-2005, 02:51 PM

When I worked at Chevy I think they mentioned some sort of vacuum leak at the transfer case or the transmission - I remember this only because it happened on 4x4's...hope it kind of points you in the right direction.

Quote: Originally Posted by Monkeyman

I have a '96 4x4 Jimmy (4.3, auto). When I turn my A/C on and "push" the motor at all (up a hill, from a start, etc), the air tends to go from the dash vents to the defroster vent. After about 30-45 seconds, it will revert back to where it's supposed to be. This also happens at other times but not as often. It doesn't matter if I have the selector on max A/C or regular A/C. It doesn't seem to do it on any other selection (vent, heat, etc).

Anybody have any ideas? It's not keeping me from driving (mostly a 60 mile round trip to work) but it's annoying as hell.

Dave

Vsandme · 07-03-2005, 03:04 PM

My camaro did that, then shortly after started blowing air directly through the defroster vent, chevy told me it was some problem with the switch

joecorlan · 07-13-2005, 05:43 PM

I have the same problem on my 95 Jimmy. Has anyone actually found the cause and fixed it?

madme · 07-18-2005, 11:10 PM

i have this exact problem in my bonneville and i did a lot of looking for the problem. i found there is a box that has ducts and what not that direct were the air goes. in this car the computer monitors and tells were the air goes i'm not sure if our trucks are like this or just vaccum opperated but if it has that kind of system in it they say you have to replace the hole box assembly which is $$$$$$. just a little info that i know if it will help

Shrike505 · 06-23-2006, 02:02 AM

Same with me on my 96 blazer under a load (going up a hill)air on MaxAC it goes From front vents to defrost then back .. seems like a Vacuum problem i gonna try to Run a new Vac source to the control switch (plug off the Old 1) an see if there is a diffrence. also i installed 2 40X40mm PC fans inside the far Right an Left Vents to improve Air Flow

Shrike505 · 06-23-2006, 09:25 PM

Update I Looked for New Vac source but no luck there i did find where the AC got its Vac source from (mounted-on-intake with the vent tube for the PCV) I am going to Try to Make a New Vac Port on my Plastic Intake(LOL) i saw a few Places where Drilling can be Done...I will look at a Junk Intake to make sure of where to Drill... i will Update ya on Progress...But back to Why the AC acts like that.. well when ya got ya blazer under a load like pulling up a hill the Vac source go's away. The PCV valve Wont need Vac when ur Under a Load (ie pullin up a hill or Just hammerin the Gas) But under regular Driving (like Miss Dasiy) its got a Full Vacuum. Hope this add's a few Ideas work arounds .

Shrike505 · 06-24-2006, 09:49 PM

New update well I routed a new Vacuum line off the Brake Booster's Vac Source an Still No-Luck looks like i am gonna Have to Drill a new Port off the INtake in Front Or maybe a blocked Off Port in the Throttle Body....Wish me Luck

mxracer2254 · 06-29-2006, 11:48 AM

I have the same problem on my 2001 s10 2.2L I checked all my vacume lines and replaced them all, I am fairly positive that I have no vacume leak. My truck only strated doing this at about 70k it was fine before that. I also replaced the switch it wasn't that. Good luck guys i have prety much given up ride with the windows down.

juddspaintballs · 06-29-2006, 10:40 PM

same exact problem on the same exact vehichle. it is vacuum definitely. I dont think I have a vac leak anywhere. I was gonna try to get either a bigger vac resovoir from a bigger truck or add a second smaller one and see if that helped the problem any. but since my AC is out of comission right now (its drained from me disconnecting it) I don't really worry about it. I hope someone pinpoints the problem though. this would be one annoying quirk i'd like to have fixed.

Jimmythang · 07-16-2006, 11:08 PM

Same problem on my 97 Jimmy... I just fixed mine today. I replaced the vacume hose that goes to the little ball that hangs from the hood. Started working right away.

Fast & Low · 07-16-2006, 11:25 PM

Quote: Originally Posted by Jimmythang

Same problem on my 97 Jimmy... I just fixed mine today. I replaced the vacume hose that goes to the little ball that hangs from the hood. Started working right away.

same here my vaccum ball hose came off and it was all dry rotted went to auto zone and got some more put it on and a/c works like it should

juddspaintballs · 07-17-2006, 12:46 PM

Quote: Originally Posted by Jimmythang

Same problem on my 97 Jimmy... I just fixed mine today. I replaced the vacume hose that goes to the little ball that hangs from the hood. Started working right away.

I replaced that same vacuum hose today too. I knew mine was dry rotted but from a visual inspection I didn't think it looked leakable. Guess it was. I spent $.36 and got a 1ft piece of hose from McHenry's Auto (local auto/small engine/paint store) and stuck her on from the vacuum ball to the t-joint in the hoses and all my AC comes out the vents like it should at Max AC under full acceleration. I'm happy.

rockyroad217 · 07-18-2006, 04:37 PM

Mine was the vacuum hose also..replaced it and it worked fine lol

NCHEVYHEVN · 07-18-2006, 05:32 PM

Best way to check for vacume leaks is with a spray bottle full of water. Spray down the vacume lines and when you find a leak the motor will change idle slightly but enough to be notice. There are other little tricks but water is free so that's what I use.

Shrike505 · 07-19-2006, 11:02 PM

Ok the Question for the Days is "where is the Vac Ball at on a Blazer?" its not under the Hood.

Fast & Low · 07-19-2006, 11:07 PM

it's the black ball that is on the hood. if you don't have one then you need one as i think all 95-97's have them and in 98 they did away with them

juddspaintballs · 07-20-2006, 01:17 AM

im gonna put either a second or a larger one in since the vac hose helped my problem alot but it still lingers somewhere and all the rest of the hoses look good...

06-10-2005, 06:25 AM	#1
Monkeyman Registered User Age: 42 Join Date: Nov 2002 Posts: 219 Location: Wabash, IN User is: OffLine	Weird A/C problem I have a '96 4x4 Jimmy (4.3, auto). When I turn my A/C on and "push" the motor at all (up a hill, from a start, etc), the air tends to go from the dash vents to the defroster vent. After about 30-45 seconds, it will revert back to where it's supposed to be. This also happens at other times but not as often. It doesn't matter if I have the selector on max A/C or regular A/C. It doesn't seem to do it on any other selection (vent, heat, etc). Anybody have any ideas? It's not keeping me from driving (mostly a 60 mile round trip to work) but it's annoying as hell. Dave
	[Reply w/Quote]

07-01-2005, 02:51 PM	#2
ras2002gt Registered User Join Date: Jun 2005 Posts: 1 Location: User is: OffLine	Re: Weird A/C problem When I worked at Chevy I think they mentioned some sort of vacuum leak at the transfer case or the transmission - I remember this only because it happened on 4x4's...hope it kind of points you in the right direction. Quote: Originally Posted by Monkeyman I have a '96 4x4 Jimmy (4.3, auto). When I turn my A/C on and "push" the motor at all (up a hill, from a start, etc), the air tends to go from the dash vents to the defroster vent. After about 30-45 seconds, it will revert back to where it's supposed to be. This also happens at other times but not as often. It doesn't matter if I have the selector on max A/C or regular A/C. It doesn't seem to do it on any other selection (vent, heat, etc). Anybody have any ideas? It's not keeping me from driving (mostly a 60 mile round trip to work) but it's annoying as hell. Dave
	[Reply w/Quote]

07-03-2005, 03:04 PM	#3
Vsandme Registered User Age: 22 Join Date: Feb 2004 Posts: 316 Location: User is: OffLine	Re: Weird A/C problem My camaro did that, then shortly after started blowing air directly through the defroster vent, chevy told me it was some problem with the switch
	[Reply w/Quote]

07-13-2005, 05:43 PM	#4
joecorlan Registered User Age: 33 Join Date: Jun 2004 Posts: 127 Location: User is: OffLine	Re: Weird A/C problem I have the same problem on my 95 Jimmy. Has anyone actually found the cause and fixed it?
	[Reply w/Quote]

07-18-2005, 11:10 PM	#5
madme Registered User Age: 24 Join Date: Apr 2004 Posts: 322 Location: Oshawa User is: OffLine	Re: Weird A/C problem i have this exact problem in my bonneville and i did a lot of looking for the problem. i found there is a box that has ducts and what not that direct were the air goes. in this car the computer monitors and tells were the air goes i'm not sure if our trucks are like this or just vaccum opperated but if it has that kind of system in it they say you have to replace the hole box assembly which is $$$$$$. just a little info that i know if it will help
	[Reply w/Quote]

06-23-2006, 02:02 AM	#6
Shrike505 Rabid-Viper06 Age: 35 Join Date: Dec 2005 Posts: 12 Location: Concord,North carolina User is: OffLine	Re: Weird A/C problem Same with me on my 96 blazer under a load (going up a hill)air on MaxAC it goes From front vents to defrost then back .. seems like a Vacuum problem i gonna try to Run a new Vac source to the control switch (plug off the Old 1) an see if there is a diffrence. also i installed 2 40X40mm PC fans inside the far Right an Left Vents to improve Air Flow Last edited by Shrike505 : 06-23-2006 at 02:22 AM.
	[Reply w/Quote]

06-23-2006, 09:25 PM	#7
Shrike505 Rabid-Viper06 Age: 35 Join Date: Dec 2005 Posts: 12 Location: Concord,North carolina User is: OffLine	Re: Weird A/C problem Update I Looked for New Vac source but no luck there i did find where the AC got its Vac source from (mounted-on-intake with the vent tube for the PCV) I am going to Try to Make a New Vac Port on my Plastic Intake(LOL) i saw a few Places where Drilling can be Done...I will look at a Junk Intake to make sure of where to Drill... i will Update ya on Progress...But back to Why the AC acts like that.. well when ya got ya blazer under a load like pulling up a hill the Vac source go's away. The PCV valve Wont need Vac when ur Under a Load (ie pullin up a hill or Just hammerin the Gas) But under regular Driving (like Miss Dasiy) its got a Full Vacuum. Hope this add's a few Ideas work arounds .
	[Reply w/Quote]

06-24-2006, 09:49 PM	#8
Shrike505 Rabid-Viper06 Age: 35 Join Date: Dec 2005 Posts: 12 Location: Concord,North carolina User is: OffLine	Re: Weird A/C problem New update well I routed a new Vacuum line off the Brake Booster's Vac Source an Still No-Luck looks like i am gonna Have to Drill a new Port off the INtake in Front Or maybe a blocked Off Port in the Throttle Body....Wish me Luck
	[Reply w/Quote]

06-29-2006, 11:48 AM	#9
mxracer2254 Registered User Age: 22 Join Date: Nov 2004 Posts: 32 Location: Mims, Fl User is: OffLine	Re: Weird A/C problem I have the same problem on my 2001 s10 2.2L I checked all my vacume lines and replaced them all, I am fairly positive that I have no vacume leak. My truck only strated doing this at about 70k it was fine before that. I also replaced the switch it wasn't that. Good luck guys i have prety much given up ride with the windows down.
	[Reply w/Quote]

06-29-2006, 10:40 PM	#10
juddspaintballs I pee standing Age: 24 Join Date: Dec 2004 Posts: 6,098 Location: Union Bridge, MD User is: Online	Re: Weird A/C problem same exact problem on the same exact vehichle. it is vacuum definitely. I dont think I have a vac leak anywhere. I was gonna try to get either a bigger vac resovoir from a bigger truck or add a second smaller one and see if that helped the problem any. but since my AC is out of comission right now (its drained from me disconnecting it) I don't really worry about it. I hope someone pinpoints the problem though. this would be one annoying quirk i'd like to have fixed.
	[Reply w/Quote]

07-16-2006, 11:08 PM	#11
Jimmythang Registered User Age: 29 Join Date: May 2005 Posts: 1 Location: Arkansas User is: OffLine	Re: Weird A/C problem Same problem on my 97 Jimmy... I just fixed mine today. I replaced the vacume hose that goes to the little ball that hangs from the hood. Started working right away.
	[Reply w/Quote]

07-16-2006, 11:25 PM	#12
Fast & Low FAH Q Age: 28 Join Date: Nov 2004 Posts: 663 Location: Kennesaw, GA User is: OffLine	Re: Weird A/C problem Quote: Originally Posted by Jimmythang Same problem on my 97 Jimmy... I just fixed mine today. I replaced the vacume hose that goes to the little ball that hangs from the hood. Started working right away. same here my vaccum ball hose came off and it was all dry rotted went to auto zone and got some more put it on and a/c works like it should
	[Reply w/Quote]

07-17-2006, 12:46 PM	#13
juddspaintballs I pee standing Age: 24 Join Date: Dec 2004 Posts: 6,098 Location: Union Bridge, MD User is: Online	Re: Weird A/C problem Quote: Originally Posted by Jimmythang Same problem on my 97 Jimmy... I just fixed mine today. I replaced the vacume hose that goes to the little ball that hangs from the hood. Started working right away. I replaced that same vacuum hose today too. I knew mine was dry rotted but from a visual inspection I didn't think it looked leakable. Guess it was. I spent $.36 and got a 1ft piece of hose from McHenry's Auto (local auto/small engine/paint store) and stuck her on from the vacuum ball to the t-joint in the hoses and all my AC comes out the vents like it should at Max AC under full acceleration. I'm happy.
	[Reply w/Quote]

07-18-2006, 04:37 PM	#14
rockyroad217 got me some 20s Age: 22 Join Date: Oct 2005 Posts: 3,951 Location: Pine Bluff, AR User is: OffLine	Re: Weird A/C problem Mine was the vacuum hose also..replaced it and it worked fine lol
	[Reply w/Quote]

07-18-2006, 05:32 PM	#15
NCHEVYHEVN NTBSSHEVN Age: 23 Join Date: Nov 2003 Posts: 9,190 Location: Creedmoor, NC User is: OffLine	Re: Weird A/C problem Best way to check for vacume leaks is with a spray bottle full of water. Spray down the vacume lines and when you find a leak the motor will change idle slightly but enough to be notice. There are other little tricks but water is free so that's what I use.
	[Reply w/Quote]

07-19-2006, 11:02 PM	#16
Shrike505 Rabid-Viper06 Age: 35 Join Date: Dec 2005 Posts: 12 Location: Concord,North carolina User is: OffLine	Re: Weird A/C problem Ok the Question for the Days is "where is the Vac Ball at on a Blazer?" its not under the Hood.
	[Reply w/Quote]

07-19-2006, 11:07 PM	#17
Fast & Low FAH Q Age: 28 Join Date: Nov 2004 Posts: 663 Location: Kennesaw, GA User is: OffLine	Re: Weird A/C problem it's the black ball that is on the hood. if you don't have one then you need one as i think all 95-97's have them and in 98 they did away with them
	[Reply w/Quote]

07-20-2006, 01:17 AM	#18
juddspaintballs I pee standing Age: 24 Join Date: Dec 2004 Posts: 6,098 Location: Union Bridge, MD User is: Online	Re: Weird A/C problem im gonna put either a second or a larger one in since the vac hose helped my problem alot but it still lingers somewhere and all the rest of the hoses look good...
	[Reply w/Quote]