Heater problem finally solved (two years!) (1 Viewer)

[Phallen]

This morning, when I started the cruiser to take the kids to school, the heat started working, which was somewhat pleasant. The issue now is the heater blows out extremely hot air. When I adjust the temperature setting when the HVAC is set to Auto, the fan speed changes but not the air temperature. Any ideas?

This has happened in the past where the heat randomly started working and only blew HOT air

Side note…. I forgot to mention in my previous post, I cleaned the servo terminals with contact cleaner. Not sure if this did anything

 

[Phallen]

Update

This morning, the heat was blowing out cool air (same temp as outside). Not sure what changed from yesterday morning and this morning.

 

[ClassyJalopy]

Have you checked if the sensor behind the driver's knee panel is connected? It need an electrical plug as well as a white small diameter plastic pipe connection. That is how the system read interior temps.

 

[Phallen]

Have you checked if the sensor behind the driver's knee panel is connected? It need an electrical plug as well as a white small diameter plastic pipe connection. That is how the system read interior temps.

I did. I’m going to replace sensor since they’re $22 a piece. While I wait for delivery, I’m going to attempt to clean the plug and the tube to see if that changes anything

 

[Biga27110]

Sounds like the Air Mix Servo is going bad. If it gets stuck on hot or cold.

 

[dealmaker]

so i followed everything he said, with no luck. last thing i did was clear out my lines going to the heater core. that made my heater work!

How exactly did you clear out your lines going to the heater core? Do you mean the tubes attached to the tee's were gunked up, or the aluminum lines at the firewall that connect to the heater core?

 

[dealmaker]

I did. I’m going to replace sensor since they’re $22 a piece. While I wait for delivery, I’m going to attempt to clean the plug and the tube to see if that changes anything

Did cleaning or replacing the sensor fix your issue?

 

[Phallen]

Did cleaning or replacing the sensor fix your issue?

I replaced the sensor and am still experiencing the problem. I think the next move would be to replace the air mix servo, which is going to be long process. I’ll have to set some days to the side to pull apart the dash.

 

[Mr Mista]

Thanks for the write up! Resetting the HVAC servo did the trick for my 99. Nice and toasty now, just in time for ski season!

 

[Phallen]

Reviving an old issue. I’ve been playing around with the HVAC this past week. I’ve found the metal arm that sits on top of the blend door actuator doesn’t fully articulate to max hot and max cold without a gentle nudge.

The ”metal arm” does move on its own but it can go past the Max Hot and Max Cold setting. For example, if I set the HVAC set to Max Hot (100% Hot), the metal arm can and will at times go past the 100% Hot mark so when I go back to Max Cold and the metal arm will move to a luke warm setting.


Any idea, if the blend door actuator is not sync’d or is it bad.

I apologize ahead of time for the wind noise in the video.

 

[Phallen]

(The photo was from the first post and I’m using it as a reference)



In the photo, the end of the rod is flush with the plastic arm. In my LC, I’ve found that the plastic arm in the photo sits higher on the metal rod, exposing the flat side at the end of the rod. Anyone know if the position of the plastic arm in the photo is correct position?

 

[Gnarwgn]

Small variation of this issue over here, hoping someone more experienced can interpret the meaning of the following:

No temperature issues (hot/cold blowing fine). Instead - floor/foot vents are just not blowing. The driver's vent directly under the steering wheel blows fine, but the two vents coming from the lower console area at both the driver's/passenger's leg/foot area aren't blowing at all. On the full floor setting, it blows the same as the defrost setting. So defrost, floor, and floor/defrost are only blowing defrost, in other words.

I think this means that the servo controlling the gate is toast? Or maybe the gate is stuck? Any ideas? Driving around in freezing temps now, and the lower half of my body is an ice cube...

 

[Bull Moose 100]

Small variation of this issue over here, hoping someone more experienced can interpret the meaning of the following:

No temperature issues (hot/cold blowing fine). Instead - floor/foot vents are just not blowing. The driver's vent directly under the steering wheel blows fine, but the two vents coming from the lower console area at both the driver's/passenger's leg/foot area aren't blowing at all. On the full floor setting, it blows the same as the defrost setting. So defrost, floor, and floor/defrost are only blowing defrost, in other words.

I think this means that the servo controlling the gate is toast? Or maybe the gate is stuck? Any ideas? Driving around in freezing temps now, and the lower half of my body is an ice cube...

remove the plastic that covers all the buttons for the HVAC and stereo, remove the vents, and look at the flaps.

I think they might be operating on a vacuum?

I sprayed some silicon lubricant on the pivoting points and it helped them open slightly more.

 

[Bull Moose 100]

View attachment 3439210



(The photo was from the first post and I’m using it as a reference)



In the photo, the end of the rod is flush with the plastic arm. In my LC, I’ve found that the plastic arm in the photo sits higher on the metal rod, exposing the flat side at the end of the rod. Anyone know if the position of the plastic arm in the photo is correct position?

I have this same problem going on, I can see the servo working but I am getting basically cold air coming in. Very frustrating. Any updates on what fixed this?

 

[Gnarwgn]

remove the plastic that covers all the buttons for the HVAC and stereo, remove the vents, and look at the flaps.

I think they might be operating on a vacuum?

I sprayed some silicon lubricant on the pivoting points and it helped them open slightly more.

A couple questions on this recc:

1. any good write ups/videos that cover this removal? never done this and would like to have something to follow if possible.

2. when its removed, will I be able to access that servo that sits behind the dash? I can see now through the crack in the passenger footwell area that the servo does not move when I flip through the air direction controls. So - I think I have located the issue, I just need to figure out how to get in there to fix the issue.

 

[Biga27110]

Reviving an old issue. I’ve been playing around with the HVAC this past week. I’ve found the metal arm that sits on top of the blend door actuator doesn’t fully articulate to max hot and max cold without a gentle nudge.

The ”metal arm” does move on its own but it can go past the Max Hot and Max Cold setting. For example, if I set the HVAC set to Max Hot (100% Hot), the metal arm can and will at times go past the 100% Hot mark so when I go back to Max Cold and the metal arm will move to a luke warm setting.


Any idea, if the blend door actuator is not sync’d or is it bad.

I apologize ahead of time for the wind noise in the video.

This servo is finally going bad for me as well. Does anyone know how to remove and replace this?