AC won't turn on, but techstream can activate the compressor (1 Viewer)

[Bull Moose 100]

I got a 2003 lx470. The AC doesn't work, but I can use the tech stream software to activate the compressor and I get cold air coming out of my vents and there are no error codes that I can see. Has anyone heard of this before?

I even brought it to a mechanic and he said the pressure is correct and that the compressor is getting power, but he didn't have a computer to look deeper into and said "take it to the dealer", no thanks

I checked pressures as well and they seem correct.

 

[nissanh]

Do you see the glass on top of the filter bubbling? the filter is located right below the driver side headlight. Also if the ambient temp is below the set limit the compressor wont come on.

 

[Bull Moose 100]

Do you see the glass on top of the filter bubbling? the filter is located right below the driver side headlight. Also if the ambient temp is below the set limit the compressor wont come on.

I pulled a full vacuum and refilled by weight. Pressures are correct

AC Sig is ON... Is this the call for AC by the computer?

Could my ambient temp sensor be broken?

 

[jerryb]

yes Ac sig is clutch signal from the button you push.

Even missing ambient signal I believe the AC would still run as long as it's set to max cool. BUT if you can't get the clutch relay on/off without techstream then something is wrong.
There is something different about the '03 regarding the blue signal line. I can't remember exactly. The wiring book would help. I'll see if it's on this latptop.

There is only one or two on here that had problems with the clutch relay on the bottom of the fuse box.
The fsm has only a few checks before the last recommended action is fuse box replacement. It's probably something else though.

i think the 04 is the same as the 03, second page you can see the sig line ACS to ECM > mag clutch.
LCs are a little different.
look in the fsm for checks.
It could be a dirty fuse. I'd exhaust all options before having a look at the center assembly AC plugs. IF someone was in there/back there recently that could be the issue also. I'd also check the line to the compressor before looking behind the center assembly.

most of the time a fix is found before reverting to a new fuse box.
BUT there is one other 04 LX witha new fuse box that had the same thing as you. That was the fix. $500

 

[Bull Moose 100]

yes Ac sig is clutch signal from the button you push.

Even missing ambient signal I believe the AC would still run as long as it's set to max cool. BUT if you can't get the clutch relay on/off without techstream then something is wrong.
There is something different about the '03 regarding the blue signal line. I can't remember exactly. The wiring book would help. I'll see if it's on this latptop.

There is only one or two on here that had problems with the clutch relay on the bottom of the fuse box.
The fsm has only a few checks before the last recommended action is fuse box replacement. It's probably something else though.

i think the 04 is the same as the 03, second page you can see the sig line ACS to ECM > mag clutch.
LCs are a little different.
look in the fsm for checks.
It could be a dirty fuse. I'd exhaust all options before having a look at the center assembly AC plugs. IF someone was in there/back there recently that could be the issue also. I'd also check the line to the compressor before looking behind the center assembly.

most of the time a fix is found before reverting to a new fuse box.
BUT there is one other 04 LX witha new fuse box that had the same thing as you. That was the fix. $500

The AC started having issues shortly after I had the engine mounts replaced.... I probably won't ever use that shop again, they installed the new mounts and tossed the old heat shields. They probably broke something or knocked something loose.

I can't get the AC to kick on when set to max cool, but I can get the compressor to engage with techstream. This is really bizarre.

I ordered a new cabin temp sensor form rockauto since it was only $20 and easy to access, but the part did not fit.

The 2002-03 nav system is different than the 2004+ which is what controls the AC and fans

 

[Bull Moose 100]

The fix was the wire going to the high pressure switch was broken!

The shop that replaced the engine mounts must have broken it

 

[ReverendDOOM]

I got a 2003 lx470. The AC doesn't work, but I can use the tech stream software to activate the compressor and I get cold air coming out of my vents and there are no error codes that I can see. Has anyone heard of this before?

I even brought it to a mechanic and he said the pressure is correct and that the compressor is getting power, but he didn't have a computer to look deeper into and said "take it to the dealer", no thanks

I checked pressures as well and they seem correct.

Sorry to revive an old thread but I'm having a very similar problem to yours but had a question to determine if it was either my pressure sensor going bad or a bad relay because I'm really not trying to bite this $600 junction box bullet. When you had your pressure sensor problem did the AC work intermittently and some times come up with the "check air conditioner system" while driving? Thanks for any input!