91 Cpaice HVAC vacuum actuator part numbers (help!) - Chevy Impala SS Forum
 
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post #1 of 4 (permalink) Old 07-18-2017, 09:40 PM Thread Starter
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91 Cpaice HVAC vacuum actuator part numbers (help!)

Ok so I've been dealing with this for as long as I've owned the car and only recently figured it out when I unplugged the vacuum connector at the TBI and plugged it. Did a little diagnosis and figured out that all of the vacuum actuators that are back there are not sealing correctly and are causing a massive vacuum leak that is starting to effect the EGR and idle. Now that its blocked off however all is well and it runs fine, except for the part where I live in Los Angeles and its hot in the summer and A/C would be nice on those balmy 100 degree plus days. My question is-are there any active part numbers for any if not all of those actuators and where might I find them?

Thanks!
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post #2 of 4 (permalink) Old 07-19-2017, 06:46 AM
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If all of the actuators are not working, I would suspect something common to them. It is unlikely that all of them would stop working at the same time. You probably do have a vacuum leak, but I would do some more troubleshooting to determine the problem.


You can borrow a vacuum tester from your local Autozone, and hook it up to the hose coming from the engine compartment. It can also be hooked up to each individual vacuum motor to determine if it is leaking. The vacuum circuit includes the distribution block, mode selector switch, and the vacuum tank. You can also check the line coming from the engine, and to the water shutoff valve in the engine compartment. You should check the water shutoff valve itself, as it is used on almost all AC modes.

1991 OCC 461 (.030 over 454) BBC, 3.23 posi, flash to pass, drop spindles & springs, Impala rims, Hydroboost, Recaros, MOMO/wood SW w/QR, custom wood shift knob, Pioneer DEH P77DH
1992 OCC now with 5.7 tbi, DEH P77DH
For a parts list, check https://www.impalassforum.com/vBulle...ion-parts.html
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post #3 of 4 (permalink) Old 07-19-2017, 07:51 AM Thread Starter
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[QUOTE=Fred Kiehl;12000625]If all of the actuators are not working, I would suspect something common to them. It is unlikely that all of them would stop working at the same time. You probably do have a vacuum leak, but I would do some more troubleshooting to determine the problem.


You can borrow a vacuum tester from your local Autozone, and hook it up to the hose coming from the engine compartment. It can also be hooked up to each individual vacuum motor to determine if it is leaking. The vacuum circuit includes the distribution block, mode selector switch, and the vacuum tank. You can also check the line coming from the engine, and to the water shutoff valve in the engine compartment. You should check the water shutoff valve itself, as it is used on almost all AC modes.[/QUOTE

Nope, I thought it was a line at first just judging by the sound but i pressurized the whole system and none of them would hold more than 5in/hg at any given time. Do they even sell the vacuum tanks or anything anymore?
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post #4 of 4 (permalink) Old 07-19-2017, 08:24 AM
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Pressurizing the system will not work to check for leaks/problems. You must pull vacuum in the system. The motors are not designed to hold pressure. I am not sure what you mean by "sounds like", but if there is a sound, there is a vacuum leak. Follow the sound, and it will lead to the leak. Proper diagnosis will find it. Check each individual part, and check the hoses for each part. The vacuum motors seldom fail, and the chances of all of them failing at the same time is approaching "0". There may be some vacuum motors available, but the only other parts that are available must come from a donor car. You can check each hose from under the dash at the glovebox. If you can not figure out which hose goes to which part, there is a diagram in the FSM that gives you the color code.



The 91 has a different through the firewall (engine) wiring harness with two hoses. All others have one hose. There are some other minor differences as well, that makes the 91 harness unique.

1991 OCC 461 (.030 over 454) BBC, 3.23 posi, flash to pass, drop spindles & springs, Impala rims, Hydroboost, Recaros, MOMO/wood SW w/QR, custom wood shift knob, Pioneer DEH P77DH
1992 OCC now with 5.7 tbi, DEH P77DH
For a parts list, check https://www.impalassforum.com/vBulle...ion-parts.html

Last edited by Fred Kiehl; 07-19-2017 at 09:22 AM.
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