No Vacuum, No Defrost!

[LBJ]

Guys and gals,

I just about finished my repair of the "no defrost" condition for my 77 Bonanza. All that was wrong was the OLD, broken vacuum lines from the intake manifold to the accumulator ball on the firewall, and the thinner vacuum line from the ball to the plastic vacuum line that goes thru the firewall. All the functions then started working as usual. I still have to replace all the ducts I removed to be through, but that's about 10 minutes work.

I will add that there is one mystery vacuum line right behind the glove box that came off because the rubber connector just fell apart. I am trying to figure that one out as I type this. Have to get the inspection mirror out to see behind the unit, I guess, since there is no obvious connection on the front side.

For all of you that have vacuum actuators, this is prolly all that is required to get things working properly.

I had a similar problem on my 91 GMC, but it had electric actuators. These were VERY hard to access. I just as soon have the vacuum jobs. Cheaper too.

By the way, I found yet ANOTHER vacuum leak at the intake manifold itself. The vacuum stub coming out of the manifold was LOOSE in the threaded hole!!! Undoubtedly leaking there. Also, the vacuum line to the tranny was loose. I used some pipe sealant on the fitting and replaced the short rubber line to the steel line to the tranny. The engine smoothed up incredibly. It sounded like it had some leaking valves beforehand. Now, it just purrs like a kitten.

I recommend checking all your lines.

[James McClure]

LBJ: The line behind the glove box goes to the "recirc" door. I think the actuator is behind the right side kick panel if memory serves. jim

[LBJ]

I found the culprit. The reason the other end of the vacuum line is not easy to find is because it's INSIDE the housing!!!! I had to stand on my head to get to it. At the same time, I found out why the doors were not closing the way I thought they should. That vacuum actuator in front of the heater box and behind the firewall (and impossible to get to without removing the unit) is a double action actuator valve. It pulls BOTH directions, but not at the same time, obviously. That's the reason for not getting good air flow at times, especially to the Defroster circuit. The hose had literally disentegrated in 3 places. The hard part was getting the new line on the horn of the valve INSIDE the housing. I worked for 30 minutes trying to figure out a way to do it. When I said I was going to war over this, I was correct. It is almost impossible to do. But, to get everything working properly, it has to be done. Now, all I need is that 3.25 inch duct hose from the center of the complex to the right side A/C vent nozzle. LMC wants $40 for that one piece of hose!!! No way. I'll find something locally before I pay that much.

[tyjoja]

do all these trucks have these vacuum actuators? I have a 73. thanks bob

[Ivan D.]

Depends if it gots factory A/C or not - his truck had it, so he got the vacuum controls, trucks with no A/C use cables to connect the control levers to the air doors.

[tyjoja]

thanks Ivan, your always helpful, bob

[Ivan D.]

np man, one of the things I know a bit too well is the Chevy non-A/C air ducting, I'm now down to like 20 minutes for a heater core replacement, lol

[LBJ]

One more victory,

Got this hose at Auto Zone for going to the rightmost air outlet. Is used for the fresh air on an air cleaner. Didn't even have to cut it. Comes complete with quick snap connector. Very solid and doesn't sag. $12 out the door. Part #96086 Mighty Flow brand. 3.25 inch ID.

Now to getting the A/C converted to 134a and charged up.

[68K20 x Drill]

My defrost actuator just failed this last storm, Guess I'll be following in your footsteps.

[chammy]

any one know where to geta schematic for this my 77 is having the ole no defrost problem. i dont even seem to have the accumulator ball... previous owner seemed to have butchered a few things. thanks
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