Malfunctioning Climate Control (2 Viewers)

[mkntrds]

New member and first post here, guys. I'm having trouble fixing a climate control problem on my 1998 LC. The system seemed to randomly cool or heat the cabin regardless of interior temperature. After fixing a loose hose issue and cleaning the interior sensor, outlined by the following thread: https://forum.ih8mud.com/threads/climate-control-temp-sensor.701917/, the problem remains. After a bit of "diagnostics" on my part, it seems as if the exterior sensor may be the issue. This morning the outside temperature read 65, but the cabin was much warmer. Irrespective of the temperature dial position, the system blew hot air in one of the highest fan settings when it should have been cooling. Is the problem with the exterior sensor, or is there another culprit?

 

[yotasavg]

Mine does weird things with the auto settings as well, defrost never works, AC only blasts on high, ever. I just don't leave it on auto, but I'm all for fixing it if someone has a solution.

 

[mkntrds]

Mine still has the same problem under manual settings, only I get to select which vent and what speed the hot air blows.

 

[yotasavg]

Oh I see, so no matter what the temp settings are, it blows hot air? Can you control fan speed or is it always on high?

 

[hoser]

Welcome, mkntrds! Good on you for doing your part in searching.

I don't know about the LC but on the LX there is a diagnostic mode on the climate control system that involves turning on the IGN and a series of buttons. This checks each temperature sensor, damper and actuator and gives a diagnostic trouble code (DTC). Maybe somebody with the LC FSM can help further.

 

[mkntrds]

Oh I see, so no matter what the temp settings are, it blows hot air? Can you control fan speed or is it always on high?

I can control the fan speed. I have full manual control, except temperature.

 

[yotasavg]

Hmmm... Seeing as that whole system is built onto a computer board type deal, I think I'd pursue what hoser mentioned. If the LX has it, I bet there's something similar to ensure the LC system is working too.

 

[mkntrds]

Welcome, mkntrds! Good on you for doing your part in searching.

I don't know about the LC but on the LX there is a diagnostic mode on the climate control system that involves turning on the IGN and a series of buttons. This checks each temperature sensor, damper and actuator and gives a diagnostic trouble code (DTC). Maybe somebody with the LC FSM can help further.

Thanks, hoser, I try not to ask questions already answered. Is this DTC something a local AutoZone could do?

 

[mkntrds]

To be clear, the problem may be random or only when its coolish outside. When the system works, say when it's 80 outside and it's really hot in the cabin, the auto controls work perfectly.

 

[Muddy Bean]

welcome mkntrds! I'll chime in here so you don't feel alone, even after I did the cleaning I outlined in that thread, my climate control temp selector just never worked perfect. It was definitely improved, but even now, we cannot set the temp to anything and just leave it there, it constantly has to be adjusted or we'll bake ourselves out or freeze ourselves out...nothing in between. I'd like to fix this too. Here are my scenarios, do they match yours?:

1. Winter: Want temp set to 75 degrees. Set the selector to 75. Truck blows coldish air, eventually freezing us out. Turn temp selector up and up and finally have it set just "one click" below the hottest setting. We leave it there for 10 minutes, then we bake. We click down "one click" cooler and after ten minutes, we're freezing. Back to "one click" back up rinse and repeat.

2. Summer. Haven't had it for the summer yet. Have no idea what happens.

 

[yotasavg]

With any luck you'll be kept nice n cool if those symptoms continue!

 

[mkntrds]

I'd like to fix this too. Here are my scenarios, do they match yours?:

1. Winter: Want temp set to 75 degrees. Set the selector to 75. Truck blows coldish air, eventually freezing us out. Turn temp selector up and up and finally have it set just "one click" below the hottest setting. We leave it there for 10 minutes, then we bake. We click down "one click" cooler and after ten minutes, we're freezing. Back to "one click" back up rinse and repeat.

2. Summer. Haven't had it for the summer yet. Have no idea what happens.

1. Winter: heater seemed to work fine
2. Hot days: a/c works perfectly
3. In-between weather, say 50 to 65 degrees outside, it acts as if it's 20 below.

 

[mkntrds]

Update: I followed the suggestion from hoser and found the following helpful diagnostic threads:
https://forum.ih8mud.com/threads/heater-ventilation-fan-blower-question.249889/
https://forum.ih8mud.com/threads/ac-diagnostic-help-please.288959/
The second link contains the relevant pdfs.


From the diagnostic self-test, I have RrDEF, DEF, and the outside temp blinking. The outside temp blink is confusing me; it is not listed on the DTC chart (unless I'm an idiot and am missing it). If I ignore that, the DTC indicates that the "detection item" is Solar Sensor Circuit (Open) / Solar Sensor Circuit (Short) and the "trouble area" is Solar Sensor, Harness or connector between solar sensor and A/C amplifier, or A/C amplifier.

Now I just need an interpretation as to how I proceed.

 

[Muddy Bean]

Did this ever get resolved?

 

[mkntrds]

Sorry for the lack of an update. I still have the same problem. I want to know how difficult it is to check connections and replace the solar sensors.

 

[TheForger]

I recently had a problem where my heater would not blow hot air. It ended up being the servo motor that moves a 'gate' at a point where hot air and cold air channels meet. When you turn the dial on your dash to the coldest position, it is supposed to block off the warm air channel and only allow cold air to pass through the vents. When its turned to the warmest position it blocks off the cold air channel only allowing warm air to pass through. Sometimes this motor can receive uncontrollable electrical pulses that make it malfunction and move back and forth constantly changing the air temp. It solved my problem, just something you can look into.

 

[yotasavg]

I recently had a problem where my heater would not blow hot air. It ended up being the servo motor that moves a 'gate' at a point where hot air and cold air channels meet. When you turn the dial on your dash to the coldest position, it is supposed to block off the warm air channel and only allow cold air to pass through the vents. When its turned to the warmest position it blocks off the cold air channel only allowing warm air to pass through. Sometimes this motor can receive uncontrollable electrical pulses that make it malfunction and move back and forth constantly changing the air temp. It solved my problem, just something you can look into.

Where's that located?

 

[TheForger]

@yotasavg Look at the pic below (passenger side floorboard). He accessed it from where the carpet is slightly untucked and I believe it is connected to that white wiring harness. When i took it to my local mechanic - Stan Helmich - he removed the servo motor but had to place an order for another one to come in later the following week. I decided to take my car home for the weekend to tow my boat and I noticed the carpet was untucked at that location and that white wiring harness was hanging out with nothing attached to the other end - so that leads me to believe this is the connection for the servo.

 

[yotasavg]

Gotcha, thanks @TheForger

 

[mkntrds]

Update: FIXED!
Sorry for the lack of update on this thread; but I've figured out the problem, and it may help others here.
After giving up, I let my mechanic try to fix it. He replaced the solar sensor. That didn't work. Then he replaced the air conditioning amplifier with a used one. This seemed to work for about a week, then complete failure. I was getting no air conditioning, except on a very rare occasion. The only part left according to the diagnostic sheet was the harness. The mechanic assured me that the harness was fine.

Luckily, he offered to me the extra used parts that came with the amplifier and I accepted them.

Frustrated with wearing a suit in a hot LC every day, I decided to swap out the old amplifier, since it worked sometimes. Looking at the extra used parts, however, I noticed something and thought wtf, why not try this first.

I noticed that behind the control panel were electronics connected to the back of the control switches. Maybe, just maybe these were going bad. So I swapped the switches and, voila, perfection! My problem was never the amplifier nor the solar sensor. It was the damn switch behind the temp control knob.