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Vacuum Flap Actuator Replacement
 
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Pelican Technical Article:

Vacuum Flap Actuator Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$85 to $170

Talent:

**

Tools:

Philips head screwdriver

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

Vacuum actuators

Hot Tip:

Use care removing the cowl cover

Performance Gain:

Working heat and A/C

Complementary Modification:

Make cabin air filters

While a true sports car, unlike the older vehicles from Porsche, the 944 is fully capable of keeping you warm in the winter and cool in the summer. Over time some of the components in the HVAC system will start to wear out and require repair or replacement. This is especially true if you live in a harsh four season environment and run the system more than a vehicle that lives in a more temperate location.

One of the components that does wear out are the actuators for the air flaps on the blower housing. These actuators control whether the fresh air flaps are open or closed. There are two actuators, one on each side of the housing. The vacuum flap actuators are run off of vacuum pressure.

The blower motor housing and actuators are located under the cowl cover piece at the base of the windshield (red arrow).
Figure 1

The blower motor housing and actuators are located under the cowl cover piece at the base of the windshield (red arrow).

Begin by pulling up and removing the rubber seal that runs along the divider between the engine bay and HVAC system (red arrow).
Figure 2

Begin by pulling up and removing the rubber seal that runs along the divider between the engine bay and HVAC system (red arrow).

You will need to remove the plastic cover (red arrow).
Figure 3

You will need to remove the plastic cover (red arrow). There is a very good chance this will not come off in one piece; these get very old and brittle over the years. If you have not removed it lately, there is a good chance you will damage it and need to replace it when removing.

With the cover off you can see the blower motor housing (red arrow) with a actuator on each end (yellow arrows).
Figure 4

With the cover off you can see the blower motor housing (red arrow) with a actuator on each end (yellow arrows). The vacuum line that controls the actuators runs along the front to the housing. There is a T nipple on the vacuum lines that joins and controls the actuator on the front right side (green arrow).

On the left actuator there is an electrical connection mounted to the actuator (red arrow) that does not have anything to do with the actuator but must be transferred to the new one when installed.
Figure 5

On the left actuator there is an electrical connection mounted to the actuator (red arrow) that does not have anything to do with the actuator but must be transferred to the new one when installed. The yellow arrow indicates the vacuum line that goes to the T junction.

The air temperature sensor is mounted to the right side actuator and must be transferred to the new actuator when installed (red arrow).
Figure 6

The air temperature sensor is mounted to the right side actuator and must be transferred to the new actuator when installed (red arrow).

Begin by checking the vacuum lines (red arrow).
Figure 7

Begin by checking the vacuum lines (red arrow). If they are dried out, ripped, torn or cracked in any way, you may have found the problem. Replacing the lines is cheaper and easier than replacing the actuators so check them first.

Replacing the actuators is the same for both sides with the exception of the electrical connection mounted to the left side (red arrow) and air temperature sensor mounted to the right.
Figure 8

Replacing the actuators is the same for both sides with the exception of the electrical connection mounted to the left side (red arrow) and air temperature sensor mounted to the right. Remove the electrical connection by gently prying it out from the mount (red arrow).

If the vacuum lines are fine and not going to be replaced, separate the line from the actuator (yellow arrow) and remove the two Philips heads screws from the mount (red arrow).
Figure 9

If the vacuum lines are fine and not going to be replaced, separate the line from the actuator (yellow arrow) and remove the two Philips heads screws from the mount (red arrow).

Gently pull the actuator forward and remove the two small Philips head screws that hold the vacuum rod to the flaps.
Figure 10

Gently pull the actuator forward and remove the two small Philips head screws that hold the vacuum rod to the flaps. Installation is the reverse of removal.

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Comments and Suggestions:
Tim Comments: If the actuators seem to be working and the flaps still do not completely close, could there be an issue with a weak vacuum pressure? If so, how would I check the vacuum pressure or what parts are involved in causing the vacuum that I might check?
April 17, 2015
  Followup from the Pelican Staff: Place a gauge on the vacuum line from the engine to the heater box, it should be equal to manifold vacuum. - Nick at Pelican Parts  

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