Ac stuck on defrost & floor

silversnake

silversnake

New member
Issue started yesterday afternoon Ac went from blowing thru the vents to the defrost shortly after hearing what sounded like..... (a good example would be a napkin being suck into a shop vac). Later that night my blend door failed and was blowing heat from the defrost/floor. Here is what I've done so far

1. Replaced blend door actuator [emoji37]
2.Repaired EATC o rings
3. No leaks as far as I can tell.



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Check for vacuum leak from the EATC to the vacuum manifold behind the intake.


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justbob said:
Check for vacuum leak from the EATC to the vacuum manifold behind the intake.


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Click to expand...



The vacuum reservoir (black box)? Or the small tree like piece with the check valve? I'm not sure what the vacuum manifold looks like. Btw my intake is on the passenger side. What's the best way to find vacuum leaks?


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Go to the boneyard find you an EATC from a newer model and see if its the unit. You can go on LKQ find a u-pick and look at their inventory. The most would be is $30, and if its not the problem return it...
 
Zack said:
The thin black vacuum line usually breaks at the firewall.
Click to expand...



I removed the EATC vacuum connector ( color lines) to see if the Black vacuum line has vaccum and it does but I'm not sure if it's enough vacuum. I'll trace the line from the firewall once car cools down.


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Gerry24 said:
Go to the boneyard find you an EATC from a newer model and see if its the unit. You can go on LKQ find a u-pick and look at their inventory. The most would be is $30, and if its not the problem return it...
Click to expand...



I thought it was a bad unit also after issue still existed after changing the o'rings. I tried my repaired unit on my buddy's marauder and everything worked like it should.


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I replaced the Ac check valve at the firewall, because I've read somewhere I may go bad. I'm convinced it's a vacuum leak somewhere. I removed the line from the vacuum canister ( black box under hood) expecting to hear the air leaking once I pulled the line and I got nothing. My buddy pulled the same line from his car and you can hear the air escape from the box.


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90* but feels 100* due to humidity right now I'm praying for the rain but weather report says 0% chance of that happening.


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Check ALL the vacuum lines.

There is a vacuum "tree" mounted to the firewall behind the intake. Start there, tracing each one.

The vacuum tank on the left fender might also have a hole in it.
 
fastblackmerc said:
Need to do more PD instead of replacing parts.
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I had to replace the blend door because that went bad blowing hot air only and after doing the EATC test it showed 025. O'rings I found 2 that were dry and broke as soon as I attempted to remove. Check valve probably didn't need to replace but I had one laying around.


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Yesterday I noticed that when I turned the Ac on by pressing (automatic) it would blow from the defrost but when I slow the fan down it started blowing from the vents once it starts blowing from the vents I can increase the fan but once I get on the gas it went back to the defrost and hasn't changed since


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silversnake said:
Yesterday I noticed that when I turned the Ac on by pressing (automatic) it would blow from the defrost but when I slow the fan down it started blowing from the vents once it starts blowing from the vents I can increase the fan but once I get on the gas it went back to the defrost and hasn't changed since


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Click to expand...

Vacuum leak...... for sure.
 
I found this image online
64b709f506f1337a5a5f78725788277c.jpg
so my focus would be the black vacuum line and it's vacuum source I assume.


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It's only one line. 1/8" black plastic. It enters through the firewall above the gas pedal.
It always breaks at or around the grommet
You'll need to remove the wiper cowl.
 
Zack said:
It's only one line. 1/8" black plastic. It enters through the firewall above the gas pedal.
It always breaks at or around the grommet
You'll need to remove the wiper cowl.
Click to expand...



Ok I'll do that tomorrow and report back my findings.


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The vacuum source comes from the intake manifold, through the check valve, then to one leg of the "T". The other legs go to the vacuum reservoir on the driver's fender liner, and to the vacuum inlet (#5) on the back of the EATC.
 
You forgot to mention that weird sound that sounded like a vacuum cleaner sucked a piece of paper, came from passenger side
 
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