HVAC controls

[cobra-bit]

I'm having an issue with my HVAC staying on the defrost setting. Everthing else seems to work fine i just cant get it off defrost....any ideas on what it could be?

thanks

 

[fivestangs]

The doors are controlled by vacuum, check that the little vacuum junction (I think it has 5 tubes running through it) is hooked up to the vacuum tree and that none of the lines are broken (they're made of plastic and get brittle and break over time).

 

[no2moro]

I agree, check the vacuum line, you can access them from the glove box and under the dash. Also check behind the HVAC controls.

 

[93Cobra#2771]

X3

 

[LEE93COBRA]

check for leaks underneath the hood (as was mentioned above) especially if you have been doing any engine work lately

 

[cobra-bit]

Thanks for the advice guys, I just purchased the car about a month ago and the motor has been rebuilt so maybe a vac line was not secured correctly or just needs to be replaced?

thanks again.

 

[fivestangs]

Not hooked up or broken, those are your 2 most likely scenarios. It's possible the vacuum motor under the dash is bad, but I would definitely go the easy route and try to verify the line going TO that motor is hooked up and not leaking.

On these cars, the hard vacuum lines get brittle and crack very easily. You have to look at the passenger side firewall for, I think it's 2 or 3 hard lines passing through the firewall from inside the car, one of those will be the line that controls the vent doors.