87 300zx Heater Problems

[jspies12345]

I have an 87 300zx that continues to let out hot air through the vents even when the heater is off...It also produces a weird smell through the vents. Any suggestions on what it could be?

[NeilAnblowme]

That's normal when your car is moving and the vent is set to open and not recycle

[evildky]

This is a common problem with Z31's. The heater valve is located on the firewall and should have a vacuum line going to it,check fir for cracking or breaks and follow it to the vac canister. The blend doors are vacuum operated, there is a single small vac hose that goes through the firewall near the battery, this provides the vacuum to operate the doors, look at this hose and trace it back to the vac canister and make sure it's not broken or cracked. If the vac hose looks to be in good order there is a series of dashpots located inside the car on top of the trans tunnel just beside the driver's right foot. Sometimes these dashpots simply stock and can be freed using a hand vac pump, sometimes the bellows that operate these valves deteriorate and need replaced.

http://xenonzcar.com/z31/hotairfromac.html

[Desert Rat]

^^ what he said. Those vacuum lines go to a canister behind the passenger side headlight and chances are they're brittle all the way down the line underhood. Go buy about 12 feet of small vacuum line and just replace it all.