Lewmc93 Posted May 12, 2020 Share Posted May 12, 2020 So had my AC recharged today after the car hasn't been re-gassed in years. Guy said the machine wont charge it if it detects a leak so he thinks its all sealed etc, but I know this can change after new gas has been added to a long time empty system I'm still getting 2 codes flashing - 2b - fresh air - abnormal refrigerant pressure. ( or Pressure switch circuit goes off another code post on the forum ) 8 - foot - open or short in evaporator temperature sensor circuit Going to have a quick check of fuses when the weather outside brightens up, but any other help on where/hopw to begin to look on these 2 faults. Cheers Quote Link to comment Share on other sites More sharing options...
Lewmc93 Posted May 13, 2020 Author Share Posted May 13, 2020 Well update, maybe this will help with replies or input. Had a fiddle round today with the AC, all fuses seem okay, I watched the little spy glass and it bubbles and eventually settles but I did notice the AC compressor clutches in and out randoml. So am assuming this is to do with the above problems but does the temperature sensor affect the ac clutching in or out, I wouldnt have thought it did. Also can't find amy wiring diagrams no matter how how i search so if anyone can provide them that would be a bonus so I can trace the wiring. Quote Link to comment Share on other sites More sharing options...
mc92 Posted May 13, 2020 Share Posted May 13, 2020 http://gallery.supra-club.ru/ftp/beast_drc/wiring/jdm_supra_wiring.pdf Try page 90 on this PDF for the diagram. Can't help you with the codes. Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 13, 2020 Share Posted May 13, 2020 Both to do with low refrigerant pressure, basically your gas is low. And the clutch will come on and off at random, thats normal operation Quote Link to comment Share on other sites More sharing options...
Lewmc93 Posted May 13, 2020 Author Share Posted May 13, 2020 http://gallery.supra-club.ru/ftp/beast_drc/wiring/jdm_supra_wiring.pdf Try page 90 on this PDF for the diagram. Can't help you with the codes. Perfect cheers will give it a look through tomorrow while in the car. Both to do with low refrigerant pressure, basically your gas is low. And the clutch will come on and off at random, thats normal operation Hm it shouldn't be low, it was pressure tested before re fill an no leaks were found and it also was re gassed with 750g of gas to the dot as per the specs. Any other guesses of what could be wrong pressure wise. When it kicks in its lovely and cold, just only get about 5 seconds of it Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 13, 2020 Share Posted May 13, 2020 Could be the sensor? You'd obviously have to vacuum it down to change it. There must be a test for it somewhere Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted May 13, 2020 Share Posted May 13, 2020 Dodgy pressure sensor can cause intermittent or all out failure causing the low pressure error code. For the temperature sensor check your wiring down near the AC rad. The evaporator temp sensor will be down there. Quote Link to comment Share on other sites More sharing options...
rider Posted May 13, 2020 Share Posted May 13, 2020 You need to get a pressure gauge onto your low pressure port and check when the compressor runs that the pressure doesn't drop into vacuum. If it does then the compressor will shut off to protect against sucking outside atmosphere into the system. That's an indication you do not have enough refrigerant in the system. You need to charge it up until you get around 14psi pressure on the LP side with the compressor running (it'll settle out to around 70psi on a normal temperature day when the compressor stops ruuning). You can buy the service port snap ons and gauges for not a lot of money. Without the gauges to work from its like tuning a car without a timing light. Quote Link to comment Share on other sites More sharing options...
Lewmc93 Posted May 13, 2020 Author Share Posted May 13, 2020 Dodgy pressure sensor can cause intermittent or all out failure causing the low pressure error code. For the temperature sensor check your wiring down near the AC rad. The evaporator temp sensor will be down there. Just found a AC fault troubleshooting doc online so will test the places you mentioned along with the guide in the manual. hopefully just a old wire nothing major. You need to get a pressure gauge onto your low pressure port and check when the compressor runs that the pressure doesn't drop into vacuum. If it does then the compressor will shut off to protect against sucking outside atmosphere into the system. That's an indication you do not have enough refrigerant in the system. You need to charge it up until you get around 14psi pressure on the LP side with the compressor running (it'll settle out to around 70psi on a normal temperature day when the compressor stops running). You can buy the service port snap ons and gauges for not a lot of money. Without the gauges to work from its like tuning a car without a timing light. Just amazon'd a Vislone R134A Refrigeration Gauge for tomorrow 12pm. So will hopefully attach that and give your suggestion a go and report back any findings. Question for you, as the system was vacuumed empty and refilled with 750g of refrigerant as per the manual specs. We know the physical amount of refrigerant is correct, would it still be possible to cause the system to pull into a vacuum ? as that would show up on the leak test would it not? Quote Link to comment Share on other sites More sharing options...
rider Posted May 16, 2020 Share Posted May 16, 2020 750g of R134a is definately top end of the Supra spec so the system, if anything should be slighly overcharged. If you do have the correct or slightly over charge in the system then you wouldn't ever run into the vacuum issue. If you find a vacuum issue with your gauge (hopefully you purchased a port snap on as well as the gauge) then either the charge wasn't 750g or you do have a leak and a good amount of it has gone away. If your inlet side pressure are fine then its onto the otlet pressures I'm afraid. Different coupler and gauge to the inlet. Should be running low to mid 200's psi with the compressor running. Less than that and your Denso compressor isn't working quite as well as it should. If all that checks out then its onto your pressure/temperature sensors or looking for a restriction in the system causing a pressure overload. Quote Link to comment Share on other sites More sharing options...
beast_drc Posted May 25, 2022 Share Posted May 25, 2022 (edited) @mc92Hey! please update link to wiring diagram https://drive.google.com/file/d/1FK0SOdJakZAdUG85cXcLlGU9FcTmjUbt/view?usp=sharing Edited May 25, 2022 by beast_drc (see edit history) Quote Link to comment Share on other sites More sharing options...
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