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Discussion Starter #1
86 Turbo with a chatter under the passenger head light. Poked my head under and there is a small diameter hose that was pulsing out some air. And now my air conditioner will stop working whenever I make 0 + pounds of pressure. When under vacuum it runs fine. I'm guessing they're related. Maybe not. I'm obvisously not familiar with a/c systems. Any ideas on the pulsing air? Thanks.
 

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I'll take a pic later today, but the hose didn't look like it was supposed to connect anywhere. It looks like a drain hose meant to dump something on the ground. But air? Didn't make sense.
 

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Sounds right. The vacuum pump has to suck some air out of the vac reservior and pump out the air somewhere. If there is a vacuum leak beyond the vacuum pump then the pump will keep trying to make some vacuum.
The vac reservoir and vac pump are assisted by manifold vacuum thorugh a hose to the plenum.
 

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Thanks for the explaination, but I'm still stumped. I have had some vaccum leaks and fixed them. The pump was not running continuously then. Now it is and I can't find any leaks. I know this kind of thing is hard to diagnose over the internet, but any suggestions about where to begin looking (again!)? Thanks.
 

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There are not too many vac lines to check.
Is the line from plenum to vac tank connected to the M port on the tank? Does the one-way valve in the M port work?
Is the line from the HVAC connected to the F port on the tank?
Is the line from the water **** connected to the magnet valve on the tank?
What is the condition of the line between the vac tank and vac pump?
What is the condition of the line between the vac tank and cruise control diaphragm unit?
Is there a vac leak in the HVAC system?
 

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thanks for the tips. I tacked down all of these lines today except for the line that goes through the firewall. I replaced a few hoses, but no change. Since my A/C is acting up, I feel pretty sure that it's in the dash. Is this something I can get to by just removing the radio and A/C controller, or do I have to take more of the dash out? Thanks.
 

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I rarely have to touch vacuum parts in the cabin. Follow the vac line through the firewall if you can.
Otherwise, plug each vac tank port one by one see exactly which part of the system is causing your vacuum loss.
 

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I wondered if I could accurately test it in that manner. I tried it on a couple of ports, but it had no effect. Should I also use this test on the canister, or only the vacuum resevoir?Mister_T wrote:
 

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Yeah, I need to complete that test. I tested it on two ports, but when it didn't make a difference I wondered if this "test" would even work as I thought it might. Good to know I was on the right track.

Yeah, I meant the charcoal canister. Will blocking those ports tell me anything? Still learning here. Thanks.
 
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