Hi, I have a 1990 z32 NA. The car never blows cold air. What's worse is that it only blows hot air and you can always feel behind the dash getting really toasty. It doesn't matter if AC is on or off it will blow hot. I have the digital climate control unit. Any ideas on how to fit it? I do see the compressor kicking on, but even if it didn't it should blow regular temperature air. Even if the air off I can feel the dash getting really warm.

Blend door actuators are the #1 culprit with your symptoms. #2 is the controller.

NolimitZ32 wrote: ↑

Wed Sep 29, 2021 2:04 pm

Blend door actuators are the #1 culprit with your symptoms. #2 is the controller.

Why does the dash get hot even if the fans are off tho? Is there something that would prevent the heat from going into the heater core? I know the previous owner swapped the dash cover I wonder if something is unplugged.

My guess is someone tried to fix it without removing the dash and screwed something up so now there is a broken or missing piece of duct. The heat would be coming from the heater core not going to it. Possibly also a heater valve bypass or other may be stuck open.

Cars with a blend door have no "heater control valve" to shut off coolant flow to the heater core like the old days. Flow through the heater core is constant, but the blend door actuator shunts the air through the A/C evap instead of the heater core when cold is selected. So if the door is stuck in the hot position, you'll always get some "flow through" hot air even if the blower is off and you'll never get cold air at all.

Found this wire under the glove box but I can't find anywhere it would connect to. Seems to come from a little computer box next to the ecu . Also these vents im not sure if they are supposed to terminate here?

Here is other pictures i'm not sure where to even start with this problem, I guess I might have to take off the whole dash cover...

This is the blend door I'm guessing? This picture is from behind the glove box



This is from the center console, sometimes that door doesnt seem to move either:


Honestly not sure how to pin point the problem.

Didnt even think about the heater control valve but thinking on it, it's TRUE there isn't one. You are correct those are the actuators. The one that switches hot to cold is in middle behind the radio IIRC. Check the fsm, it should show you the location.

Okay, I checked the ESM and your ride is a sort-of hybrid, it has a blend door but it also has a motorized water valve driven by a second blend actuator. Actuator-2 drives the water valve and is likely responsible for the heat, but I think both actuators would have to be faulty for the temperature to be unchanged when the A/C is on. That could be a wiring problem, but I think it's more likely you have a faulty in-car or ambient temperature sensor that's making the Auto system think the car is in Siberia. Both actuators are located on the bottom of the HVAC, see page HA-108 in the ESM. There's also a pretty good description of the sensors starting on HA-104:

https://www.nicoclub.com/service-manual ... 0%2Fha.pdf

When checking the sensors, keep in mind that higher voltage means lower temperature. It's a balance circuit; the fixed resistor inside the controller pulls up and the variable resistor in the sensor pulls down. That means they'll usually read "Siberia" if they're disconnected, which may explain your problem.

I have the digital display version which does show the correct ambient temperature, so I guess the sensor outside must be good?. Tomorrow I'll try the steps on HA-119 to determine which sensor is bad using the display. Thank you for the service manual link.

If im reading the guide right its showing no error codes on all the sensors.. I'm thinking of maybe getting a consult scanner to try to give me a clue. It does seem like air on the sides blows at air temperature while the center console slowly gets hot over time. Eventually it gets so hot that it warms up the entire cabin too much.