Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - View Single Post - AC just quit blowing cold all of the sudden

Blackmetal · 03-11-2022, 05:50 AM

Hey bro , let me give you a few words of advice .im a ASE MASTER TECH and TOYOTA MASTER TECH for nearly three decades . DTC 25 is stored unless you are in DIRECT sunlight (sun load sensor ) . DTC 20 simply indicates diagnostic check is completed . You won't find a DTC for compressor operation as that HVAC Check is intended to start diagnosis of air distribution ,recirculation, auto functions and blend mechanisms . So try this -

1) gauges are preferred but in a pinch you can put some gloves on and safety glasses ...take off either service cap ....using a golf tee or chopstick or similar item carefully and quickly depress the schraeder valve in the center of service port ....if you get ANY blast of pressure ,this would indicate enough refrigerant to close low pressure switch and your system is "full enough" to allow compressor operation . IF NOT - as in almost no pressure - your system is empty and you need to find the leak source . Look for oily dust around components in AC system including hose crimps and all components ( refrigerant carries oil within the system so when it leaks it's usually fairly easy to inspect visually since you probably don't have an electronic leak detector or black light )

Low system pressure will not allow compressor operation by opening the relay control circuit to ground.

2) using a test light hooked to a solid ground or negative battery terminal , probe compressor mag clutch power feed wire when AC is switched on and blower is operating - if you have 11 volts or above , then the problem is compressor clutch field coil ( which I would suggest complete compressor Assy)

3) if no power on feed wire to mag clutch under same conditions as above - you would move over to the AC mag clutch relay underhood and tap on it , squeeze it ,etc. ( AC SWITCHED ON ) . If it engages , the relay has failed which is fairly common .

4) also at that time , find another relay in the box like horn or cooling fan that is the same style and swap them .if compressor operates go buy a new relay ( make sure you get dealer or at least DENSO)

Get that far and let me know , I'll do the best I can to guide you thru remotely .

03-11-2022, 05:50 AM	#23
Blackmetal Junior Member Join Date: Jan 2022 Drives: 2019 toyota 86 TRD SE 6MT Location: Vista , CA. Posts: 1 Thanks: 0 Thanked 2 Times in 1 Post Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Hey bro , let me give you a few words of advice .im a ASE MASTER TECH and TOYOTA MASTER TECH for nearly three decades . DTC 25 is stored unless you are in DIRECT sunlight (sun load sensor ) . DTC 20 simply indicates diagnostic check is completed . You won't find a DTC for compressor operation as that HVAC Check is intended to start diagnosis of air distribution ,recirculation, auto functions and blend mechanisms . So try this - 1) gauges are preferred but in a pinch you can put some gloves on and safety glasses ...take off either service cap ....using a golf tee or chopstick or similar item carefully and quickly depress the schraeder valve in the center of service port ....if you get ANY blast of pressure ,this would indicate enough refrigerant to close low pressure switch and your system is "full enough" to allow compressor operation . IF NOT - as in almost no pressure - your system is empty and you need to find the leak source . Look for oily dust around components in AC system including hose crimps and all components ( refrigerant carries oil within the system so when it leaks it's usually fairly easy to inspect visually since you probably don't have an electronic leak detector or black light ) Low system pressure will not allow compressor operation by opening the relay control circuit to ground. 2) using a test light hooked to a solid ground or negative battery terminal , probe compressor mag clutch power feed wire when AC is switched on and blower is operating - if you have 11 volts or above , then the problem is compressor clutch field coil ( which I would suggest complete compressor Assy) 3) if no power on feed wire to mag clutch under same conditions as above - you would move over to the AC mag clutch relay underhood and tap on it , squeeze it ,etc. ( AC SWITCHED ON ) . If it engages , the relay has failed which is fairly common . 4) also at that time , find another relay in the box like horn or cooling fan that is the same style and swap them .if compressor operates go buy a new relay ( make sure you get dealer or at least DENSO) Get that far and let me know , I'll do the best I can to guide you thru remotely .