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problems with climate control doors no longer working


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so here the problem i've changed over to a dual diaphragm brake booster . and since the change over my climate control doors for defrost floor and vent don't work now . just blows through the defrost vents ? i still have the small round vacuum canister , so far i've checked it for leaks using a vac brake bleeder tool . it holds vac and i've replaced the vac line from it to the manifold , is there a way to fix this or do i just need to go to the jy and get the larger vac can ? or would an inline vac pump work like whats on the newer jeeps ? 

 

thanks in advance 

 

 

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You don't need a larger vac can for the new booster. If the vac system and HVAC doors were working fine before you changed the brake booster, therein must be the problem? Check the booster vacuum check valve. If okay, try the below procedure:

 

Test Power Brake Booster

If the pedal feels "hard" while the engine is running, the booster isn't operating correctly. If you suspect the booster is defective, do not attempt to disassemble or repair the power booster. Doing so is unsafe and will void your warranty.

Test 1

  1. With the engine off, pump the brake pedal to remove any residual vacuum in the booster.
  2. Hold pressure on the pedal while you start the engine. When the engine starts, the pedal should drop about a 1/4", this indicates that the booster is working properly.

Test 2

  1. Run the engine a couple of minutes.
  2. Turn the engine off and press the pedal several times slowly. The first pump should be fairly low. The second and third should become slightly firmer. This indicates an airtight booster.

Test 3

  1. Start the engine and press the brake pedal, then stop the engine with the pedal still pressed. If the pedal does not drop after holding the pressure on the pedal for 30 seconds, the booster is airtight.

Inspect the Check Valve

  1. Disconnect the vacuum hose where it connects to the intake manifold. Do not disconnect the vacuum line from the booster. Air should not flow when pressure is applied, but should flow when suction is applied. If air flows in both directions or there is no air flow, the valve needs to be replaced.

Verify Enough Vacuum

  1. Check the operating vacuum pressure when the engine is at normal operating temperature. There should be a minimum of 18 in. of vacuum. Vacuum may be increased by properly tuning the engine, checking for vacuum leaks and blockages in vacuum lines.
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cruiser54 no i have not checked that vac line to the firewall , hornbrod the booster seems to be working ok but i didn't know about the testing , or even think to check the check valve on it . i'll check both suggestions after work today when i get home . i'll update what i find 

 

thanks 

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i did disconnect some vacuum lines on the drivers side but only the ones that went to the factory air box that is no longer in the truck but that's been gone for over a year . and this just started after installing the 95 cherokee booster . i'll look at that vacuum line running up by the battery also .

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Just throwing this out there ....

 

You didn't happen to disconnect the vacuum hoses on the servos / diaphrams on the drivers side of the HVAC box ?

 

This^^^ check under the driver's side of the dash and look for the colored vacuum lines and make sure they are still connected.

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so after checking all of the suggestions this weekend i found the vacuum leak . it was the line going into the firewall . somehow it got a hole rubbed in it fixed the hole and secured the line from rubbing on anything . 

 

thanks for the help 

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