binZer

Just bought a 280zxt, and am trying to sort the awful climate control out.

We have replaced the vacuum hoses in the engine bay, and have narrowed the problem down to the vacuum switch. The vacuum switch works, but it is not receiving vacuum, so the blower does not come on unless the vacuum switch is bypassed (like it is in defrost mode). If we physically suck on the hose going to the switch the blower comes on no problem.

So the question is, any ideas on what might be causing a lack of vacuum to the vacuum switch? This system is extremely overwhelming and we're having a hard time troubleshooting it any further.

Thanks!

NismoPick

Hehe... Welcome to the Datsun Auto Climate Control from HELLLLL!!! Oh... and welcome to ZDriver.

There's about 20 vacuum lines attached to the ACC, and if any one of them has a leak, it defaults to defrost / floor. I converted to ACC only to convert back to manual after I could not get it to work correctly. I suggest doing the same, as you will have the dash all apart anyway looking for that cracked hose.

binZer

It's not defaulting to defrost really, it just only works in defrost. In the other modes the blower doesn't go on at all.

If we can't figure this out I'll probably do a manual swap, but that means I have to track all the manual parts down, so I'm going to give this another few days of fiddling at least. We already managed to fix some OTHER problems with the climate control, so I remain foolishly hopeful.

I'm glad I'm not trying to swap to ACC; fixing it is hard enough! I guess climate control just wasn't meant to exist in the 80's :P

NismoPick

That is default (aka "limp mode"), and that's exactly what mine did. When I pulled it back out I found 6 or 7 cracked vac lines.

lifegrddude

Try replacing the blower motor relay. Mine did the same thing until I replaced it with a spare. Auto and manual relays interchange so don't worry about which kinda zx you pull it off of.

binZer

Which vacuum lines? We replaced all the ones in the engine bay, but haven't really done any in the dash, although they visually look pretty good. We know it's not the relay, but we're going to try to trace along some hoses and figure out how far back there is no vacuum.

Thanks for the replies so far! Seems like there are a lot of people who have had ornery climate control to deal with.

NismoPick

There's only two AAC vac lines in the engine bay, all the rest are under the dash. Both manual & AAC control all vent ports via vac lines, which means that if there is a vac leak anywhere in the system it goes back to default. The AAC has many more vac ports to "automatically" adjust to current needs. On the back side of the sliders (inside the dash above the radio) you will find a huge conglomerate of connections... one or more of the lines is likely cracked, thus stopping vacuum to all needed ports. A trusty Haynes manual or FSM will help a lot.

WildmaN

Is there a relay for the manual climate control also? My blower motor quit working a while back. And I could never figure out why. If I have to still drive this Z in the winter. I need it working..so I can use my heat. I loved the heater in my Z. Anyway let me know...and thanks...also where it is too..lol

lifegrddude

Wildman, it's attached to the motor itself. If you look under the motor, you'll see two or three screws or bolts (I can't remember) and if you remove that, the relay will come out. When I changed my system over to the manual climate, I checked the auto and manual relays, and they are identical even if they have different part numbers. Lol my heater is the only thing good about the zx as far as climate control goes. I have no A/C as the PO trashed the compressor and a bent the lines till they fatigued and broke.