AC and heat not working

[Sonic_ZX]

I've got a '90 300zx Twin Turbo with Manual climate control.

For some reason the heat and AC are not working, only the blower turns on.
I've tried changing the control pod, and AC Relay, but nothing changed.

Actually the only thing that works on the control pod is the blower settings and the rear wiper.

What could be the problem?

[Ace2cool]

Hm, do any of the controls/indicators show up? Does the temperature even show?

[BigTDogg (MA)]

Hm, do any of the controls/indicators show up? Does the temperature even show?

Manual climate control, no temperature read out.

OP, check your fuses, that's the first place to start. There are some in the footwell by the clutch, and two boxes in the engine bay. I don't have the FSM infront of me now, but there should be one labeled HVAC, and I would check that first. If not a fuse, it's probably a fused relay.

If you don't have an FSM, you can find one for the 1990 here. Go up a directory or two and that's Nico's repository of FSMs.

[Ace2cool]

Oof, I'm off my game lately. Good catch Tony. Here's the Climate Control section, as shown in the link Tony posted.
http://www.nicoclub.com/FSM/300zx/1990/ha.pdf

Think it could be the blend door seized up and the freon needing a recharge? Or possibly the heater core is bypassed and the A/C compressor isn't switching on. There could be about 11345295394 things wrong with a CC system, and on a manual unit, there's no self diagnostics. :/

Do the vent selectors change anything? No lights when you press the A/C button? Nothing at all? If nothing at all, I agree with Tony to check fuses. Both in the Driver's side kick panel and the engine bay.