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AC Programmer (ACM)


Scotty

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I have been having a slow parking brake release. I replaced the parking brake vacuum servo motor. I come to find out that part of the ACM's job is to release the parking brake. Other symptoms I am getting are no air out of the vents on acceleration. I checked and there are no holes in the vacuum line from the engine to the vacuum tank.

I also have a problem where suddenly, my windshield fogs up badly and the RECIRC light comes on while the system is on AUTO. I am thinking that the ACM needs replacing. Can the ACM leak vacuum if its defective?

Does anyone have any ideas on this

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Mike,

Theoreticaly, it is possible to leak vacuum as vacuum is controled by the ACM, but to my understanding they are pretty reliable. Have you checked the vacuum diaphram on the parking brake? If that is ok, I'd start checking the vacuum hoses off the ACM to the air delivery doors and parking brake.

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Mike,

Theoreticaly, it is possible to leak vacuum as vacuum is controled by the ACM, but to my understanding they are pretty reliable. Have you checked the vacuum diaphram on the parking brake? If that is ok, I'd start checking the vacuum hoses off the ACM to the air delivery doors and parking brake.

Thanks Larry, that is what I was thinking. I also need to replace the L-shaped connector at he black vacuum tank, if I touch it it will leak vacuum, maybe that is causing this.

I edited my original post above to say that I replaced the parking brake vacuum servo, Thanks

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Well ,based on what you said, my money is on the "L" connection at the reservoir. That is a perfect job for JB Weld. Just let it set up for 24 hrs.

I actually bought a new connector from caddy, but I can't find the new nylon tubing anywhere. Can the tubing be purchased caddy did not have it...

You think if I can induce a leak by touching it, that could be my problem?

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Have you put a vacuum gage on it to see what what it measures? I am having the same problems that you are right now and the vacuum reads about 5 hg at idle, I think it should read just over 20 hg. Taking it back to the dealer tomorrow to see if they can find the leak, will post what they find.

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I put a vacuum guage at the parking brake vacuum hose, and at the T that leads to the vacuum storage tank and as you said I got around 20.. I am interested in what they find, Thanks

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Had to replace the controler on my 96sts it was internittant on blower speed and heater-defrost control when weather was in 90 to 100 deg range,this was after replacing the blower motor this was the last straw sold the car and bought a 96 deville ultra clean . don't even miss all the problems with the sts.sts96

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I just requested a price quote on the ACM. I am going to replace the fitting at the tank. I am going to try to find some of that nylon vacuum tubing, maybe I can buy it, I asked for a price quote on that also.

This problem is on the bottom of the list right now, I am in my research mode.

I have to insulate my garage ceiling (it is not heated and there is living space above it, imagine THAT?!?, the room above it is an ice box blink.gif ) and do my front struts first.

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The AC Programmer is $254 OUCH, time for a visit to my favorite scrap yard. Hopefully the connector at the tank is leaking intermittantly.

The dealer DOES have the nylon tubing for $13, nice, its called the Heater & AC Vacuum Tank Tubing.

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Scotty,

My 96 SLS has emergency brake release problems too. I figured out that it only happens after a long drive. Today I had a no-release-situation again, but this time in my shop :-)

So I removed the the lower plastic panel on the drivers and passengers side (the shields above the feet). I removed the vac connector at the pedal servo and hooked up a vac gauge. There was NO vacuum at all at the servo with the shift lever in "drive".

Then I removed the vac feed line to the HVAC programmer to find that I get 19 Hg there. So no vac supply problem on my car.

Then I wiggled the electrical connectors at the HVAC programmer (noticing that the whole thingie is pretty hot, drove for an hour beforehand with heater on, no a/c).

After that wiggling the parking brake release started working again...

So may be it's an electrical problem? Could it be that due to the heat, which may affect electrical connectivity, it had no contact at the connectors?

For now I left the passenger side panel off, so that I can reach the programmer easily. If the condition returns, I will try to duplicate the effect to verify the cause.

Maybe this is worth a try for you?

Hope this is understandable, difficult for me to explain in English!

Stefan

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Have you put a vacuum gage on it to see what what it measures? I am having the same problems that you are right now and the vacuum reads about 5 hg at idle, I think it should read just over 20 hg. Taking it back to the dealer tomorrow to see if they can find the leak, will post what they find.

Got my car back from the shop today. The Vacuum line from the vacuum canister that goes back to the firewall (up around the surge tank) was the culprit. Brake release, AC vents all working normally now. The car also feels like it has a lot more power, I guess that make sense since it was only pulling 5 Hg's and now it is pulling about 15 Hg's.

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Have you put a vacuum gage on it to see what what it measures?  I am having the same problems that you are right now and the vacuum reads about 5 hg at idle, I think it should read just over 20 hg.  Taking it back to the dealer tomorrow to see if they can find the leak, will post what they find.

Got my car back from the shop today. The Vacuum line from the vacuum canister that goes back to the firewall (up around the surge tank) was the culprit. Brake release, AC vents all working normally now. The car also feels like it has a lot more power, I guess that make sense since it was only pulling 5 Hg's and now it is pulling about 15 Hg's.

Hey thanks for your feedback, I ordered that tubing today for $13 from a caddy dealer, I previously ordered the L-shaped fitting at the vacuum tank, Thanks

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