Cab A/C switching output when accelerating

[papademuchos]

I finally had a moment to get back under the hood and look at this, referencing your comments and what to look for. I've looked for a "ball" and a check valve and don't see one. I referenced videos and am guessing they are in the "hard to get to spot" on the left side of the engine.
Under the hood, in this picture I'm holding the connection where the red line used to be:



Right now, this is simply disconnected.

Under the passenger side, same thing. I cut the black wire coming in from the engine compartment (from the reservoir???) and connected it to the red wire as seen here:



This goes up to a plug that has three connections on one side and two on the other. I noticed that one of the three connections does not have a hose on it:



So a couple of questions with these extra pictures: It's my understanding that I simply bypassed the hose under the hood, so I don't need to cap that. Is that right? And the same for the cut hose on the inside. So where would I add in a check value with this configuration?

Is it the reservoir that I bypassed? If so, that would explain why it's not able to draw from the reservoir, 'cause it's not in the vacuum line anymore.

Is that third hole my problem? I'm not sure if something broke off of there, or if it's meant to be like that and it's plugged. Can I just hold my finger to it to see if there's suction or if I'm losing vacuum?

Thanks again!

[THenne1713]

Having just worked on the serpentine system, I had the question enter my mind, "if compressor locked up, and blew belt, and you had spare SHORTER serpentine on hand roadside, WOULD IT FIT AND INSTALL RE-ROUTED BY OTHER DIAGRAM WITH COMPRESSOR NOT REMOVED? So should we all also carry a spare (shorter, properly labeled) "NO AC BELT"?

[THenne1713]

First= Red/black is PLASTIC VACUUM TUBING, NOT WIRE; 2) You are ADDING a New VACUUM CHECK VALVE where the red/ black join, (because it is such an accessible location); you leave in place the OEM check, if bad, causes no issue to leave as long as FACTORY VACUUM CANISTER RESERVOIR IS GOOD (= Not leaking); YOU DO NOT SEE THE BALL CHECK BECAUSE YOU HAVE NOT YET ADDED THEM; 3) If WORST CASE= OEM canister= LEAKS= then BEST/easiest is ADD NEW RESERVOIR CANISTER UNDER PASSENGER DASH, AND 4) add new tubing between new check and new canister and connect to existing tubing for DASH CONTROLS. IN SUMMARY: WORST CASE= You basically abandon bad parts IN PLACE (where YOU cannot find them anyway) , YOU BYPASS OLD PARTS with NEW TUBING and install two new parts at different (accessible) locations.
= Basics= plastic is 1/8"OD, new rubber (1/8"ID rubber tubing fits the plastic fine) and is 1/4"OD, SOME vacuum parts use 1/4"ID barbed fittings (SOME use BARBED 1/8").. SO YOU USE COMBINATIONS OF TUBING TO MATCH WHATEVER PARTS YOU WERE ABLE TO SECURE.= to fit together Have never seen plastic tubing in auto stores? GOOD LUCK.

[THenne1713]

PIC 3871085 i cannot orient my mind to where that is? Under hood, or under passenger dash? Maybe diff from mine? If you have good reservoir and tubing and JUST a bad check, just ADDING new check where red plastic joins Black plastic MAY solve your issue? If VAC-RESERVOIR/ tubing is leaking, then further work needed. Do you understand? The DEVICE you show in 371084 w/ red arrow I cannot identify mine are buried out of sight.

[papademuchos]

The first picture where I'm holding the black tube is from under the hood. The other two are under the passenger dash.

Thanks for spelling it out for me! So I need to add in a check valve under the passenger dash area where the red and black are currently connected. If that doesn't solve the problem I add in a new canister.

[kwftlaud]

I was able to put a 2 port vacuum backflow switch in the line on the red vacuum line. It was a $8 part. Fixed my vacuum problem, 2 minuet fix.

The factory vacuum check valve is burried and impossible to get to, so you can't change it. All the youtube videos have you reroute the vacuum lines and adding a new canister, but all i did was add another check valve and it worked for me.


Kip

[THenne1713]

Originally Posted by papademuchos

The first picture where I'm holding the black tube is from under the hood. The other two are under the passenger dash.

Thanks for spelling it out for me! So I need to add in a check valve under the passenger dash area where the red and black are currently connected. If that doesn't solve the problem I add in a new canister.

EITHER typo in yours above, or yours is different? I had NO RED Under dash, and vac reservoir canister and check valve assembly inaccessible, so I ADDED NEW CHECK VALVE ONLY Under HOOD where red from engine joined Black; this alone can fix IF your ONLY problem is check valve. IF FURTHER ACTION REQUIRED, (re: Reservoir leak) I added RESERVOIR UNDER PASSENGER DASH, bypassing old, bad parts under hood with new RUBBER 1/8" ID VACUUM TUBING, AND an 1/8" barbed plastic T-fitting to tie in a new reservoir, that I mounted under dash.



The black vacuum line that went thru firewall in passenger footwell I pulled real hard, it came loose from hidden parts, and I pushed new tubing (about 5-foot pushed thru) thru the SAME rubber grommet ** in firewall at passenger footwell, and THEN underhood, with coat hanger bent to small V- hook, was able to locate and pull up to connect to new check valve. HOPE THIS IS CLEAR AND HELPS? (** Youtube had some who drilled thru forward of passenger door, or others who drilled thru by doghouse, but by reusing old hole, drilling new holes= NOT required to get thru firewall.= faster, easier.)


p.s. I also found in my 18yo rig that PO had tied all dampers to mid-position, so removed all ties in panel on TOP CENTER of Dash, which restored normal operation after my repairs.