LS430 (04) intermittent air con

Antharro · July 27

Hey forum. 🙂

My '04 LS430 has an odd A/C problem I'm hoping you can help me diagnose.

From a cold start, the A/C will not work. Nothing at all. However, if I drive a few minutes down the road, switch off completely, start the engine again, there is a strong chance it will start working. If it doesn't, then if I get the revs up to above 3000 rpm, it will kick in with a vengeance - it was vacuum tested and regassed last year and it's still blowing VERY cold. Once it's going, it will keep going as long as the revs are above a certain level - for example, if I'm motorway driving. If I drive in town, it'll cut out after a few minutes and usually won't turn on again until I either cycle the AC on and off, then get the revs up to 3000 or above for a few seconds. If that doesn't work then switching off the entire car, and starting up again will usually do the job. This problem was present last year when it was regassed - they had trouble getting it to kick in.

I've pulled the air con codes, or rather code - 35 - "max cool damper position sensor circuit (passenger side)". Having looked into this I can see that it would be a problem, but would it prevent the air con working at all, or cause these intermittent symptoms?

My feeling on this is it's the compressor, but as (as far as I know) I can't manually force the compressor to kick in on this facelift car, I can't test that.

I've got the diagnostics document for the code, so I'll run through those; I can do all of it except the bit that requires the DLC3 tester.

Any air con experts on there?

Thanks!

ambermarine · July 27

35 minutes ago, Antharro said:

Hey forum. 🙂

My '04 LS430 has an odd A/C problem I'm hoping you can help me diagnose.

From a cold start, the A/C will not work. Nothing at all. However, if I drive a few minutes down the road, switch off completely, start the engine again, there is a strong chance it will start working. If it doesn't, then if I get the revs up to above 3000 rpm, it will kick in with a vengeance - it was vacuum tested and regassed last year and it's still blowing VERY cold. Once it's going, it will keep going as long as the revs are above a certain level - for example, if I'm motorway driving. If I drive in town, it'll cut out after a few minutes and usually won't turn on again until I either cycle the AC on and off, then get the revs up to 3000 or above for a few seconds. If that doesn't work then switching off the entire car, and starting up again will usually do the job. This problem was present last year when it was regassed - they had trouble getting it to kick in.

I've pulled the air con codes, or rather code - 35 - "max cool damper position sensor circuit (passenger side)". Having looked into this I can see that it would be a problem, but would it prevent the air con working at all, or cause these intermittent symptoms?

My feeling on this is it's the compressor, but as (as far as I know) I can't manually force the compressor to kick in on this facelift car, I can't test that.

I've got the diagnostics document for the code, so I'll run through those; I can do all of it except the bit that requires the DLC3 tester.

Any air con experts on there?

Thanks!

Take it to Lexus the issue could be within the ecm and only the right diagnostic equipment will find it ,the a/c shops don't have the kit for in depth diagnostics.

steve2006 · July 27

By any chance was the cabin filter replaced at the same time as the aircon re-gas?

Antharro · July 29

@steve2006 As far as I know, no; that's usually done with the annual service.

steve2006 · July 31

Just a thought, apparently the control flap for airflow can be damaged if it is not set in a particular position when replacing the filter so given the fault codes it may have something to do with the fault?