Troubleshooting HVAC Issues

[TXFJ60]

I'm about to start working on the HVAC issues on my new to me 1995 Suburban 2500. This is my first GMT400, though I grew up in these and GMT800's. I'm hoping someone can help point me in the right direction. It appears that most of the A/C components under the hood have been replaced. The blower works well with the switch, but air will only blow on the feet (no hands or defrost). I can hear the hand/feet/defrost direction mode trying to do something when I switch between hands/feet and defrost (see video). And I sort of hear a change when I change the temperature, but there is no change in the temperature. This all makes me think that the actuators are working since I can hear a change. What should be my next step? Do I go ahead and remove the dash to look for the culprit? Can I open up the lower part of the box without removing the dash? I'd rather not just buy parts without confirming what the problem is.

Mode Change Sound:

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[slow_c1500]

I had some similar problems. If I were you I would start by checking the mode and temperature actuators to see if they work. U can access either without dash removal. The mode one (it controls where the air is blowing from) is underneath the drivers side of the dash, above the gas pedal. The temperature one is a little trickier to get to, but dash removal is still not necessary. It is behind the cigarette lighter area, you will need to take off some of the lower dash trim pieces to access it.

Troubleshooting is the Same process for both, except you need to remove some trim pieces to access the temperature one. Turn the appropriate dial on the HVAC panel, and then quickly look back down at the actuator to see if the little white circle part spins. If it does spin, then it’s responding to the dial and it’s working.

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I don’t really know anything about the third actuator, which I believe is the recirc one.

 

[rockR67]

I've been going through this on my '99 burb. You can look up under the dash close to the accelerator pedal, and you'll see the actuator that controls the "blend doors" or vent controls. I've got a shot of it below, but really, it should have the actuator motor direct-driving the floor vent, and then two levers extending to the defrost vent and then the other mid vent. In the photo below, my broken unit has a zip tie that is trying to hold a vent closed because there's a lever missing.

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So my suggestion is start there and see if a) the actuator is moving (grey circle thing is the motor's connection to the lower floor vent) and that b) the levers are there and also moving.

If the motor isn't moving, an easy fix would be to swap it out with a new one, it's the easiest one to get to in that system by far. The other reason if isn't moving could be because of a jammed vent door that it just can't move. I understand that sometimes these fall off their pivot points inside.

So one step at a time, see what you can find - hopefully an easy fix!

 

[GoToGuy]

It would be big help if you download the service maunals for your year here in forum. Enter "service manuals " in the search at top. Select the paragraph with link. Get the 95 OE service Book 1 and Book 2 . Your new best friends.

 

[TXFJ60]

@slow_c1500 @rockR67 @GoToGuy

Great feedback! I shifted and started fixing some other issues. I'll download those manuals and take a look at the mode actuator this evening.