Cruise control not "pulling".

[57lxi]

This problem cropped during the return on the "trip from hell". On the run out there, cruise would hold very well, even downshifting from 4th to hold speed on steep hills. I usually rest my foot gently on the gas pedal when in cruise and I could feel the pedal go almost to the floor in some cases (steep hills). One the trip back it would not hold speed very good, the "accel" feature did little to help. When it would start loose speed, I would "help" the pedal down. When I did this, I noticed my AC vents in the dash would quit working and blow out the defroster vents. Soon as I backed off the pedal, or shut the cruise down, AC vents would act normally. This leads me to believe I have an issue with the cruise vac actuator. #1. Where is the actuator located? #2. Am I on the right track?

[harofreak00]

Sounds like you have a vacuum leak actually. Spray some carb cleaner on all the vacuum lines and see if you can get the idle to change.

[wjcollier07]

If you went WOT...I know the A/C compressor clutch disengages...but there also might be something there that changes the mix actuator too. Odd to say the least...

You most likely either have a vacuum leak, or more likely, your cruise control servo is dying. They do this when the parts inside dry up and crack...no longer completely sealing and make a total vacuum.

[Jrs3800]

Its not a Vac leak yet...

The Vac line to the HVAC, and the Cruise servo run off the same line.... More than likely the Vac line is degraded and being sucked flat killing off vacuum.... Replace those Vac lines and I'll be the problem goes away...

[imidazol97]

This problem cropped during the return on the "trip from hell". On the run out there, cruise would hold very well, even downshifting from 4th to hold speed on steep hills. I usually rest my foot gently on the gas pedal when in cruise and I could feel the pedal go almost to the floor in some cases (steep hills). One the trip back it would not hold speed very good, the "accel" feature did little to help. When it would start loose speed, I would "help" the pedal down. When I did this, I noticed my AC vents in the dash would quit working and blow out the defroster vents. Soon as I backed off the pedal, or shut the cruise down, AC vents would act normally. This leads me to believe I have an issue with the cruise vac actuator. #1. Where is the actuator located? #2. Am I on the right track?

You might have a leak in the storage tank on the firewall for the vacuum which serves both. The tank is subject to heat. I believe some people have had the connector for the vacuum hose crack off the tank.

There is a vacuum one-way valve in the line to the tank on the firewall to keep the tank (and HVAC and cruise) from losing vacuum too fast when the vacuum in the intake manifold drops such as during a long 2/3 throttle acceleration up a hill in a higher gear so that the vacuum is not great inside the UIM. That valve might have failed.

Or you've got a vacuum leak in deteriorated rubber line from the UIM to the vacuum storage tank and beyond. That rubber gets bad after time, oil, heat...

Another possibility is there is a vacuum leak in a vacuum motor for the HVAC that is activated in whatever was the mode you were using. That leak was letting enough air in to deteriorate the ability of the cruise to get enough vacuum and the HVAC to have enough vacuum. The test would be to shut off the HVAC and see if it occurs on a long hill acceleration. Test your HVAC in all settings to see if they all work with the motor running. Listen for a vacuum leak when each on is on--try getting down next to the tunnel while doing that!

The cruise also has a diaphram that could have a leak in it.

At the vacuum tank, you can plug the line going to each one with a golf tee and see if your car still does it.

My bet is on the deteriorated vacuum lines around the motor especially at the hottest end on the motor that someone else already mentioned. You'll be able to pull the rubber apart with your fingers easily.

The Series II in my 98 as the hard plastic type line in most parts for the HVAC (the cruise is electric).