84 ac/heat control
Instructor
Joined: Sep 2011
Posts: 107
Likes: 0
From: Colorado
It could be the diverter flapper. Can you hear it change when moving the control? If not you probably don't have vacuum. the valve is located on the lower passenger foot rest. My '85 doesn't have the plastic so I can get to it. The line is yellow. First check your vacuum lines on the engine.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The problem is most likely with the vacuum source in the engine compartment.
The vacuum check valves are well-known problem sources. About $4 at any auto parts store. You're looking for one of these guys:
The vacuum check valves are well-known problem sources. About $4 at any auto parts store. You're looking for one of these guys:
Thread Starter
Instructor
Joined: Jul 2013
Posts: 217
Likes: 0
From: Hoxie Kansas
Ok I replaced check valve.
Did not fix the problem.
Vacuum line going to motor is good. Line going to cruse ect is good.
My question is the vacuum line that goes down. it is plastic. I going to guess that is has a crack or broke off. Question is where does it go?
I see it going down but that's it.
Would it run in a wire loom?
Did not fix the problem.
Vacuum line going to motor is good. Line going to cruse ect is good.
My question is the vacuum line that goes down. it is plastic. I going to guess that is has a crack or broke off. Question is where does it go?
I see it going down but that's it.
Would it run in a wire loom?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
It goes into the wire loom and into the cabin through the bulkhead feedthrough behind the passenger side head. It attaches to the rear of the HVAC control head.
This pic from Agent 86 shows the vacuum line very well (behind the pink distributor power wire):
This pic from Agent 86 shows the vacuum line very well (behind the pink distributor power wire):
Le Mans Master
Joined: Jul 2004
Posts: 6,228
Likes: 698
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Ok I replaced check valve.
Did not fix the problem.
Vacuum line going to motor is good. Line going to cruse ect is good.
My question is the vacuum line that goes down. it is plastic. I going to guess that is has a crack or broke off. Question is where does it go?
I see it going down but that's it.
Would it run in a wire loom?
Did not fix the problem.
Vacuum line going to motor is good. Line going to cruse ect is good.
My question is the vacuum line that goes down. it is plastic. I going to guess that is has a crack or broke off. Question is where does it go?
I see it going down but that's it.
Would it run in a wire loom?
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Thread Starter
Instructor
Joined: Jul 2013
Posts: 217
Likes: 0
From: Hoxie Kansas
Best I can tell the vacuum lines at the hvac unit in dash are in god shape.
I see 2 vacuum line coming off unit. Black and yellow.
I took the passenger under dash apart and I see where the yellow line goes. Looks good.
I see 2 vacuum line coming off unit. Black and yellow.
I took the passenger under dash apart and I see where the yellow line goes. Looks good.
Last edited by wendal; Mar 12, 2014 at 02:47 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Running a new vacuum line into the cabin might be a little difficult. It goes through this guy (bulkhead feed through):
It's basically a plastic box filled with some kind of sealer. The sealer is about 1" thick. That little white "thread" in the center is what was left of my vacuum line after it got melted in a fire.
Thread Starter
Instructor
Joined: Jul 2013
Posts: 217
Likes: 0
From: Hoxie Kansas
thanks for the pictures.
I am hoping the problem is a line in the engine compartment.
Does the feed line run from the check valve directly to the bulk head or does it route around the passenger side of the car?
I am hoping the problem is a line in the engine compartment.
Does the feed line run from the check valve directly to the bulk head or does it route around the passenger side of the car?
Thread Starter
Instructor
Joined: Jul 2013
Posts: 217
Likes: 0
From: Hoxie Kansas
I ran a temporary vacuum line from the check valve into the cab and to the back of the hvac unit. Still no change, Took off the white round plug with several vacuum lines in it. I di not have any vacuum on the back side of it?
Can that part be bad?
My deed line has very good vacuum. I do not here any leaks.
Can that part be bad?
My deed line has very good vacuum. I do not here any leaks.
Racer
Joined: Oct 2011
Posts: 312
Likes: 0
From: state of insanity
Had the same problem in our 84; after much wasted time of searching for the problem it turned out to be a broken vacuum line. I was in the shop working on it when a neighbor walked in blowing his cigar smoke in my face, he thinks its funny. ya ha ha. but then it hit me,i pulled the vacuum line off the motor and had him blow his smoke into the line. low and behold after several blows smoke was seen coming out down by the starter. opened up the harness and found the vac.line broke in half. on ours that was the routing on its way to and from the heater control valve. repaired broken line problem solved. not saying that's your problem,but if you can blow smoke through it you may find a or if theres a break. just my 2 cents
Thread Starter
Instructor
Joined: Jul 2013
Posts: 217
Likes: 0
From: Hoxie Kansas
Ok I think I got it. Have to run a new vacuum line. I think the hvac selector valve was pluged.
Anyway got it working. Thanks guys
My next problem is my cable switching from hot to cold. It is kinda stiff but the black outer part of the cable need to be held in place. When holding it by hand it works great.
Anyway got it working. Thanks guys
My next problem is my cable switching from hot to cold. It is kinda stiff but the black outer part of the cable need to be held in place. When holding it by hand it works great.