AC control switches not working, stuck on defrost (1 Viewer)

[Shaysoverlander]

All three AC control switches on my 2000 Landcruiser suddenly stopped working. I have searched the forum and could not find anything that matched my issue. Dug the LC out of the snow yesterday and started it up to discover the thermostat is stuck on defrost - low, I am thankful because I still have some heat for the time being until I can figure this issue out. In the past I have had problems with the 'rear' and 'AC' buttons, I have found that pressing and wiggling side to side is effective. All the other buttons: rear defrost, mirrors, F/R, antenna, and hazards work fine. Some things to note: Only the defrost light is on and does not change no matter what position the switch is changed to. The fans speed dial has no lights illuminated no matter the position. I tried to perform the diagnostic sensor check mentioned in the manual, however I cannot get it to work. When I hold down the AC and F/R buttons then turn the key to the On position nothing happens. I am expecting all the lights to blink four times then it should light up the indicators to show where the fault is. I have also performed a resistance check on the ambient temp sensor and it passed. I have checked the CIG fuse and it was good. Around the same time I got a CEL P0155 code for 'O2 Sensor heater circuit bank 2 sensor 1'. This seems unrelated, correct me if I am wrong. I removed the knobs and found that the nuts were loose, I tightened them and they still did not work. I suppose the next step would be to remove the panel and check the circuit board. Any help would be greatly appreciated!

 

[nissanh]

Defrost is the defaulty setting so your control pannel might be in default mode due to some failure in the HVAC system.

How about the fan speeds? does it change upon selecting different speeds?

There is a thread about getting those "rear" and other switches fixed in a very simple manner see below. I did it about a month ago to get my "A/C" and "Rear" switches to work every time (post 95)! Did you press those non functioanl switches too hard? did it crack the PCB? Some recommends to replace the entire switch by desolder and resoldering the new, but the simplest method is to remove and replace the rubber boot (find it tiowards the end of that thread)

I'd advice you to get the necessry switches before you pull the HVAC control unit out.

100 Series Button Repair How-To - A/C, Defrost, Recirc etc

Bringing topic back up.. Does anyone have link to buttons with rubber cups which I can use? One link above points to UK eBay and they wouldn't ship to US, another link points to Overstock which doesn't seem to work either.. I can resolder, but I'd rather keep it stock Is this what your...

forum.ih8mud.com

 

[NMuzj100]

With strange electrical issues I find Its always good to start by testing the battery, it's cables and connections and the alternator. When the voltages drop or fluctuate all kinds of strange problems can pop up.

 

[Shaysoverlander]

Defrost is the defaulty setting so your control pannel might be in default mode due to some failure in the HVAC system.

How about the fan speeds? does it change upon selecting different speeds?

There is a thread about getting those "rear" and other switches fixed in a very simple manner see below. I did it about a month ago to get my "A/C" and "Rear" switches to work every time (post 95)! Did you press those non functioanl switches too hard? did it crack the PCB? Some recommends to replace the entire switch by desolder and resoldering the new, but the simplest method is to remove and replace the rubber boot (find it tiowards the end of that thread)

I'd advice you to get the necessry switches before you pull the HVAC control unit out.

100 Series Button Repair How-To - A/C, Defrost, Recirc etc

Bringing topic back up.. Does anyone have link to buttons with rubber cups which I can use? One link above points to UK eBay and they wouldn't ship to US, another link points to Overstock which doesn't seem to work either.. I can resolder, but I'd rather keep it stock Is this what your...

forum.ih8mud.com

The fan speed control switch was also unresponsive and did not light up. I did partially read that thread you mentioned but did not get to post 95, I will be replacing the boots on those switches in the future.

Yesterday I pulled the control console out of the truck brought it inside and took it apart, and performed the lighting test in the repair manual, and inspected the PCB, I did not see any damage to the board. All the lights lit up during the test so I re-installed it. When I turned the LC on all the controls were working! I suppose if this happens to someone else on this forum they can try unplugging the console letting it warm up inside and then re-install it, and it may start working again like mine did.