Advice needed: AC Diagnostic mode for 99 LX470. (1 Viewer)

[gpxl]

I'm trying to figure out why the compressor clutch isn't engaging on my LX and I saw that there is a diagnostic mode for Land Cruisers by holding the R/F and A/C buttons while turning the ignition to ON. The same sequence does not seem to work on my LX.

 

[planomateo]

Hold the R/F and Auto buttons while turning on it.

 

[flintknapper]

I'm trying to figure out why the compressor clutch isn't engaging on my LX and I saw that there is a diagnostic mode for Land Cruisers by holding the R/F and A/C buttons while turning the ignition to ON. The same sequence does not seem to work on my LX.

You'd be getting ahead of yourself even if it did.

When was the last time the clutch DID work?

When the clutch was working (last) did you have cold air?

You can bypass the pressure switch (just for a few seconds) to check and see if the clutch is capable of engaging (or is faulty).

IF the clutch works when the pressure switch is bypassed then we need to look to see why the circuit is not being called for or completed (Low refrigerant charge, faulty pressure switch, bad connections, wiring, controls)?

 

[gpxl]

Hold the R/F and Auto buttons while turning on it.

Thank you!

 

[gpxl]

You'd be getting ahead of yourself even if it did.

When was the last time the clutch DID work?

When the clutch was working (last) did you have cold air?

You can bypass the pressure switch (just for a few seconds) to check and see if the clutch is capable of engaging (or is faulty).

IF the clutch works when the pressure switch is bypassed then we need to look to see why the circuit is not being called for or completed (Low refrigerant charge, faulty pressure switch, bad connections, wiring, controls)?

I'm just starting to troubleshoot but that and seeing if there are any codes are #1 & 2 on my list. The vehicle is new to me and I bought it last winter so I don't know if the AC has worked anytime in the recent past. I know I should have checked but that's hindsight for you!

 

[gpxl]

I tested the compressor for resistance and it came back as 9.9k. I also bypassed the pressure switch and the clutch engaged immediately. I looked at the codes and got 23 and 47. It looks like 23 is the air intake temp sensor but I can't find anything on 47.

What should I do next? This is the first time I've tried troubleshooting AC

 

[gpxl]

One more thing, pressure on the low side is around 70 psi.

 

[planomateo]

47 = Rear Air Mix Damper Control Servo Motor Circuit

 

[gpxl]

Ok, I'm an idiot. I checked the pressure switch next and found that I forgot to plug it in after installing my ARB bumper. AC is working fine now. Guess this thing is more reliable than its owner!

 

[flintknapper]

Ok, I'm an idiot. I checked the pressure switch next and found that I forgot to plug it in after installing my ARB bumper. AC is working fine now. Guess this thing is more reliable than its owner!

Good deal!

That's why I advocate checking the simple stuff FIRST, before getting bogged down with codes. Not that codes aren't helpful, but for the most part...they just point you in a direction. The vast majority of A/C issues will be found by just checking the condition of the compressor, the refrigerant charge, your leads and connections.

Thanks for the follow up post, it might be helpful to someone else down the line.

 

[gpxl]

Good deal!

That's why I advocate checking the simple stuff FIRST, before getting bogged down with codes. Not that codes aren't helpful, but for the most part...they just point you in a direction. The vast majority of A/C issues will be found by just checking the condition of the compressor, the refrigerant charge, your leads and connections.

Thanks for the follow up post, it might be helpful to someone else down the line.

Thanks for your help. It was actually your post that made me think to check the pressure switch as a next step.