johnmikeyo

Hi,
I am new to the cl forum and recently purchased a 1999 sc400 with aprx. 118000 miles on it. When driving about every ten minutes the a/c lite will blink. I then turn it off and aprx. ten more minutes goes by and starts blinking again. this will go on all day. A/c seems to work fine as well as all the other climate control parts. However when I do run the a/c and radio at the same time this will drain my battery. Alternator was replaced 4 years ago and the battery will hold a charge once I put it on a trycle charge. Any help or suggestions will be greatly appreciated. I did the a/c diagnostic code and read a 21 but that was a past issue. No beep when 21 came up.

P.S. I've heard the renaissance red sc have always been the fastest, in stock mode of course

O. L. T.

iTrader: (17)

compressor code

Zerodrag

iTrader: (5)

Mine did that when the alternator was on the way out. (it died shortly after). I think there's another thread somewhere on the forum regarding that also.

KahnBB6

iTrader: (5)

This can also be due to a low freon condition due to a leak. The system is designed to lock out the compressor from use to protect it and the rest of the system if this happens.

I believe there is a diagnostic procedure through the HVAC unit itself which will tell you trouble codes. That procedure should be in the SC300/400 FSM.

johnmikeyo

Thanks for the help. I will do a test on the freon level this weekend and report back the results. The alternator needs to be tested as well. That could lead to the battery eventually draining. Other than this issue the car is a
pleasure to own and drive.

johnmikeyo

Ok, so I went to put my hvac gauges onto my system and found that I need some quick coupler connecter adaptors to test my a/c system and charge it if necessary. The gauge connections on my hoses are both threaded. I did use the site glass on the vehicle to check the Freon flow and found with a/c on high that it would show minor inconsistent bubbling followed by a whitish frothing flow. When shut off the flow would stop with some bubbles then it would be clear. Anyway I don't think that by filling up on Freon will stop my dying battery issue but does anyone think it my halt the a/c lite from coming on and blinking aprx. every 10 minutes? Any thoughts will be greatly appreciated.

Zerodrag

iTrader: (5)

I would check the voltage output of your alternator. AC should have nothing to do with your battery drain issue.

johnmikeyo

Does anyone know what it means when the sight glass for the a/c shows that the r134a refrigerant is frothy when passing thru the site glass? is that an indication that it is low on coolant? And would you trust the coolant that comes from the auto parts store that's in a do it yourself can application? Could I just add it slowly until the site glass is clear of any bubbles or frothing white flow?

johnmikeyo

Update: I recharged my system with r134a with a friend who is an A/C expert. The low side fitting on the car is a bit challenging to get the fitting on. Anyway charged the system, and although it's blowing colder now, the A/C lite still comes on intermittently. I used an alternator tester and it showed the alternator is not operating properly. I am going to do the Big three grounding project. If that doesn't fix the alternator issue it just may be time for a new alternator, although it was replaced along with the power steering pump aprx. 5 years ago at Lexus dealership. I cannot see any leaking from the power steering pump. Hoping the grounding project works. Any thoughts or input would be greatly appreciated. Thanks

LEXXIUM

iTrader: (1)

Check your heater valve and the hose routing to it. My valve on the firewall went out not giving me a heat in the winter, when I bypassed the valve to get some heat, the ac light intermittent blink appeared. I would check the heater valve, hoses that go to it and the sensor attached to it as well.

O. L. T.

iTrader: (17)

Alternator code should go through the red security light as I recall. Compressor code, which is vague at best, could be anything involving the AC system. Most report no issues with the compressor when the blinking first appears, then later having compressor failure.

Since you know you have an alternator issue, replace it and see if your parasitic drain goes away if thats the route you wish to go, but the proper way to trace it is install a DMM with ampere capability and pull each fuse (reinsert if no change) until the amp drain stops.

johnmikeyo

Thank you for the help. Can you tell me what DMM stands for? Also, would you do the grounding project first, or just replace the alternator. I was hoping the grounding may help to eliminate the alternator issue. Or am I just wasting time?

BiGEZ

iTrader: (24)

DMM--- Digital Multi Meter. I had the same issue a while back and ran the diagnostics only to get all clear/no codes.
My alternator failed shortly afterwards so I replace it and the issue just corrected itself. Could not figure it out so I chalked it off as a bad charging system. Have not had an issue since.

Zerodrag

iTrader: (5)

Here's the other thread with a similar issue I was referring to earlier, regarding the A/C light and alternator...

https://www.clublexus.com/forums/sc-...ng-off-ac.html

johnmikeyo

O.L.T. Can you tell me a little more in depth how to track down a parasitic drain with a DMM? Or anyone that is familiar with this process. Would I test with the car running? Also where would I attach the leads when checking the fuses. IT would be a big help if I could test the electrical system and understand how it works. Thank you.