1997 40th - AC/Heat Control Issues (1 Viewer)

[KZN130Alabama]

I've had an issue with my 97' 40th (Auto A/C) since I've owned in that the heater control valve cable did not move. I initially thought the cable was broke or seized but have recently ruled that out as I've pulled enough of the bezel/controls/stereo to see and touch the other end of the cable/servo. I cannot move the servo by hand and while I'm not sure if this is normal, I can at least confirm the cable itself is fine. The only other thing that doesn't work is the recirc button. It doesn't appear to do anything.

I removed and disassembled both the a/c amplifier and the controls. I don't see anything out of the ordinary on either. I also tried using the switch to manual on back of controls.

I'm just trying to figure out at this stage if I can somehow test the A/C Amplifier before spending big bucks on one. Would it be worth trying another set of controls? If I use pre-97 manual controls, will it "bypass" the a/c amplifier and potentially move the servo?

Any insight is appreciated.

 

[NKP Garage]

Have you checked the heater control valve? Fairly cheap part that's easy to replace.

What are the actual symptoms you are having? No hot air? No cold air? No air blowing?

Here's how to replace the heater control valve incase that helps:
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[KZN130Alabama]

Have you checked the heater control valve? Fairly cheap part that's easy to replace.

What are the actual symptoms you are having? No hot air? No cold air? No air blowing?

Here's how to replace the heater control valve incase that helps:
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Yes, heater control valve is fine. I can remove the cable and freely move the valve by hand to control temperature but that's obviously not ideal going down the road. I removed the cable from the servo last night and verfied the cable moves fine on it's own. The issue appears to be something upstream of the cable (servo motor, amplifier, controls).

 

[Malleus]

There's a servo inside the control unit in the dash that moves the cable. You can't move the cable by hand without damaging it, but you can energize it and verify that it functions properly, although, given your description, it isn't working.

I gave a thought to opening on, once, but IIRC it appeared to be sealed or glued shut, and I wasn't interested in destructively removing the cover to get at the internals at the time. The A/C amplifier doesn't directly interact with the control of the cable, so replacing it won't help you. Another auto A?C unit will work fine, although finding another 40th may be hard. You should look for an LX450 unit.

Yes, any climate control unit will work, you'll just lose the auto air function. I recommend downloading the '97 FSM/EWD from the Resources section, if you haven't already done that. A/C electrical details are found on pages 170-189 in the EWD, which covers both auto and manual A/C operation. The A/C section of the FSM is the last 103 pages.

 

[Malleus]

 

[KZN130Alabama]

There's a servo inside the control unit in the dash that moves the cable. You can't move the cable by hand without damaging it, but you can energize it and verify that it functions properly, although, given your description, it isn't working.

I gave a thought to opening on, once, but IIRC it appeared to be sealed or glued shut, and I wasn't interested in destructively removing the cover to get at the internals at the time. The A/C amplifier doesn't directly interact with the control of the cable, so replacing it won't help you. Another auto A?C unit will work fine, although finding another 40th may be hard. You should look for an LX450 unit.

Yes, any climate control unit will work, you'll just lose the auto air function. I recommend downloading the '97 FSM/EWD from the Resources section, if you haven't already done that. A/C electrical details are found on pages 170-189 in the EWD, which covers both auto and manual A/C operation. The A/C section of the FSM is the last 103 pages.

Thanks for the information. This is very helpful. Controls seem to be cheaper and easier to acquire than the amplifier.

I removed and opened the controls yesterday. I cleaned out the slider part with compressed air but doesn't seem to have done anything.

I may try the test you posted with ohm meter and use a friend's controls to verify that's the issue.

 

[Malleus]

Got any photos of the inside of the control? The FSM is silent on the internals; I assumed there was a solenoid in there.

 

[KZN130Alabama]

Got any photos of the inside of the control? The FSM is silent on the internals; I assumed there was a solenoid in there.

I did not take any, but I used this guy's YT video.

 

[Malleus]

Gotcha. I was thinking about the near end of the cable, the one not connected to the water valve. It's been a while since I was in there.

 

[KZN130Alabama]

Gotcha. I was thinking about the near end of the cable, the one not connected to the water valve. It's been a while since I was in there.

Yea, there is a motor on top of that assembly but there's no way to get to it without removing the entire dash.

 

[Malleus]

That's why I couldn't remember it; it's been years since I did that.

 

[KZN130Alabama]

I was able to come up with another amplifier and I was able to confirm that is not my issue. Next step will be to try a different set of controls.