SOLUTION AT BOTTOM. READ THIS BEFORE YOU REPLACE TXV / COMPRESSOR / PRESSURE SWITCH / CLIMATE CONTROL UNIT
I've been troubleshooting my AC for a while now, but when I was troubleshooting, I experienced new issues. This is sorta to document my troubleshooting process and also to ask for help.
I've replaced the following:
There's no more leaks, which is what I started my troubleshooting journey with. It holds refrigerant perfectly fine.
The compressor clutch was working last night when I filled my AC. I put 12 oz of R-134a in, no leak sealer or unmetered PAG oil, and vacuumed out for about an hour. I didn't want to put in an entire charge to find out the compressor needs to be replaced and have it evacuated again.
This morning I started electrically troubleshooting the AC pressure switch, located in the AC Dryer. The test results were:
![Image]()
![Test 9 and chassis ground with your multimeter]( "Test 9 and chassis ground with your multimeter")
I used a jumper wire to connect the source in the under dash fuse box directly to the pressure switch, and then jumpered the other wire to the climate control 30P connector wire 24 (BLU). Since there's continuity across the AC pressure sensor, there's the same 11.5 volts on both terminals at the pressure sensor. EDIT: This voltage was coming from Air Mix Hot, not the correct wire.
![Image]()
Now when I turn my car to Ignition position II, the radiator fan and condenser fan both turn on. Does this mean my pressure switch is bad? My manifold gauges show 90 PSI on both the high and low side. The pressure switch activates at 28 PSI and 455 PSI, so I don't believe the pressure switch is the problem.
It's worth mentioning with the jumper connected to the Climate Control 30P connector, pin 24, and the car in ignition position II, the rad and condenser fans turn on. Switching the AC on or off doesn't change this at all. When I disconnect the jumper, the AC light turns on and off, but the fans don't turn on.
This indicates to me that the climate control AC switch is bad, but maybe the pressure switch is bad also? The clutch still isn't turning on. I'll keep testing and report back on my findings, but I'd appreciate some help here.
![Test 24 and chassis ground with your multimeter]( "Test 24 and chassis ground with your multimeter")
*** EDIT: This is super important, when the manual says "Wire Side of Female Terminals", that means you're looking at the terminal from the side with the wires coming out. This might be obvious to some, but it wasn't to me. Make sure you're probing the BLUE wire. The mirrored one is pink and yellow, and I'm colorblind and I was working in the dark and didn't notice.
I did end up with both of the wires going to the AC Pressure Switch / Sensor being open somewhere in their travel. I cut some jumper wire and routed them through the firewall and soldered them up and my AC started cycling normally.
I've been troubleshooting my AC for a while now, but when I was troubleshooting, I experienced new issues. This is sorta to document my troubleshooting process and also to ask for help.
I've replaced the following:
- AC Condenser
- AC Dryer
- AC Thermal Expansion Valve
- Rebuild Heater Core Assembly / Replaced Evaporator
- AC Compressor (3 Years Old Now)
- Various Seals
- Fuse 14 (Under Dash) OK
- Compressor Clutch Relay OK
- Blower Motor Relay OK
- Radiator Fan Relay OK
- Condenser Fan Relay OK
There's no more leaks, which is what I started my troubleshooting journey with. It holds refrigerant perfectly fine.
The compressor clutch was working last night when I filled my AC. I put 12 oz of R-134a in, no leak sealer or unmetered PAG oil, and vacuumed out for about an hour. I didn't want to put in an entire charge to find out the compressor needs to be replaced and have it evacuated again.
This morning I started electrically troubleshooting the AC pressure switch, located in the AC Dryer. The test results were:
- Continuity across pressure sensor OK
- No voltage to wire 1 or 2 on the connector side (Weird)
- 11.5 volts at connector F, wire 9 (IIRC) In Cabin Fuse Box OK
I used a jumper wire to connect the source in the under dash fuse box directly to the pressure switch, and then jumpered the other wire to the climate control 30P connector wire 24 (BLU). Since there's continuity across the AC pressure sensor, there's the same 11.5 volts on both terminals at the pressure sensor. EDIT: This voltage was coming from Air Mix Hot, not the correct wire.
Now when I turn my car to Ignition position II, the radiator fan and condenser fan both turn on. Does this mean my pressure switch is bad? My manifold gauges show 90 PSI on both the high and low side. The pressure switch activates at 28 PSI and 455 PSI, so I don't believe the pressure switch is the problem.
It's worth mentioning with the jumper connected to the Climate Control 30P connector, pin 24, and the car in ignition position II, the rad and condenser fans turn on. Switching the AC on or off doesn't change this at all. When I disconnect the jumper, the AC light turns on and off, but the fans don't turn on.
This indicates to me that the climate control AC switch is bad, but maybe the pressure switch is bad also? The clutch still isn't turning on. I'll keep testing and report back on my findings, but I'd appreciate some help here.
*** EDIT: This is super important, when the manual says "Wire Side of Female Terminals", that means you're looking at the terminal from the side with the wires coming out. This might be obvious to some, but it wasn't to me. Make sure you're probing the BLUE wire. The mirrored one is pink and yellow, and I'm colorblind and I was working in the dark and didn't notice.
I did end up with both of the wires going to the AC Pressure Switch / Sensor being open somewhere in their travel. I cut some jumper wire and routed them through the firewall and soldered them up and my AC started cycling normally.
