HLS

Having an issue with Air conditioning controls. Most of the controls are vacuum driven. I have about 15-17 inch of vacuum going into the canister. However, I only have about 4-5 on the output which is used to open and close doors in the duct work. My question is... do I have bad controls which do not get the full 4-5 inch of vacuum to the actuator... or should I have more vacuum coming out of the canister. 4-5 inches seems low to me, but what do I know. New controls are around 150.00 and not easy to change. But if I had more vacuum, I think the controls would work just fine.


Does any know how much vacuum should be on the output of the canister.
By the way, I measured the vacuum by disconnecting the hose from the canister going into the dash and measuring it right at the canister output.

Fun71

I was under the impression that the vacuum canister was just a reservoir. If so, it should have the same level of vacuum on the output as it has on the input. If no one posts an answer in the next day or so, I can measure mine and report back.

HLS

That would be fantastic. And I do agree... I would think there should not be any loss of vacuum there.

hookem horns

Just an idea, but try temporarily bypassing the canister to see if the controls work better with the full 15-17" of vacuum.

Koda

A vacuum canister is there to provide a reservoir for operation of vacuum controlled stuff when the engine does not make vacuum, ie, full tilt hammering. For vehicles with vacuum leaks, this results in fun behavior like the AC blowing warm for a few seconds, or the airflow shifting to the defroster for a bit, or even the joys of pneumatic windshield wipers where the faster YOU go, the slower THEY go. Those of us who have experience with the @1970 Ford Bronco*, amongst others, may remember such.

I believe your canister is compromised, sir. I recommend you plug the output, and use a vacuum pump on the input and pull 15 inches and see how long you can hold it. Also, temporary bypass will, like suggested above, may provide better results, other than the transients I mentioned up above.

*= If you ever found vacuum leak on your Bronco hunting vehicle on the old dead wipers, and fixed it by plugging the hose with a twig, you might be a redneck. BTDT.

Professur

A reservoir of vacuum ... I can die happy now .. I've officially heard it all.

Professur

I can't be the only one who keeps golf tees in his tool bag for this purpose.

Nop

You know: If there are 4 people in a room, and 6 people walk out, 2 people have to walk in to have no people in the room...

BTT:

Are these




somewhat usable vac gauges, and where do I measure if I have, say, 14-17" Hg? ? At the canister, manifold side?

Koda

Technically, it's a "reservoir of low pressure air" but I was using industry, not scientific, parlance.

Professur

I know ... It's just there's a part of me that takes a childish glee in hearing such things.

Koda

Ah ok then,

Glee on, good sir.