when i turn on the ac just the fan comes on not even the light on the knob inside to tell me the ac comes on is their a fuse or a relay somewhere i can not find it and i sweating like an animal in this so cal heat… any help or had this happen
do u know for sure that ur a/c ever worked to begin with? good on refrigerant? do u hear the compressor cycling? is the clutch switch connected? does ur blower motor turn on? we need more details.
Check fuse 17 - 7.5A, [hot in run] in under dash fuse box.
Do not just eyeball the fuse, test it or replace it with a known working one, [new].
All the A/C switch is doing, when turned on, is supplying a ground to the A/C indicator light, power for indicator light is constant from fuse 17, when ign. switch is in run, the switch also supplies a ground to the “A/C Pressure Switch”, if A/C refrigerant, [R134a] is within limits, the ground will pass through the A/C pressure switch and into the “A/C Thermostat”, if A/C thermostat switch is closed the ground will pass through and go to “A/C Diode” pack, [turning on rad fan if the condensor fan comes on] and the ground from the A/C thermostat also goes to the ECU/ECM, the ECU/ECM in turn will supply a ground to the A/C compressor clutch relay, the relay in turn supplies 12V+ to the compressor clutch coil.
Power for compressor clutch and condensor fan relay is from fuse 20 - 15A, [hot at all times] in under dash fuse box, fuse 20 is also power for the “Radiator Fan Control Module” in USDM G2s, [CDM G2s do not have a “Radiator Fan Control Module”
Back to the A/C switch, where you will have to start your testing, the A/C switch get’s the ground it supplies from the blower fan speed switch, blower fan switch must be on, any speed, for the A/C switch to work.
The first test, assuming blower switch was on and blower motor works, is to test the ground output of the blower switches green lead, or the input to the A/C switch, green lead, it should test as ground when blower switch is at any speed, except off.
Next is to test the output of the A/C switch, [blue/red] it should test as ground when blower switch is on and A/C switches are on, [if there is a ground then the A/C indicator bulb is blown] if that is all good move on the the A/C pressure switch, two pin switch, [both leads are blue/red] mounted in the A/C high side line, sorry, not exactly sure where on a G2 the pressure switch is, but it will be on the thinner of the two A/C lines].
Once you find the switch test for ground on one of the blue/red leads when blower and A/C switches are on, if there is a ground, start car, turn blower fan switch all the way up, turn A/C on full/high, and use a jumper, [I use a paper clip] to jump the two leads in the A/C pressure switch plug, if A/C compressor turns on you have either a defective A/C pressure switch or a low A/C refrigerant charge.
A set of A/C gauges need to be hooked up to tell if it is a low charge, not unusual on a car that is almost 20 years old.
A simple test would be to uncap a A/C service port and press the schrader valve, [kind of like a tire valve] unfortunately it will only tell you if there is some or no A/C refrigerant in the system, not if it is the correct amount.
If it is compleatly empty there is a leak in the system and to find it gauges are needed and the system needs to be pressurized with nitrogen.
Leaks can be as simple as dried up “O” rings or as bad as holes in evaporators, condensers, hoses or lines, bad schader valves or blown front seal on compressor or the compressor case itself. 94
PS, if compressor turns on when you jump the A/C pressure switch plug, do not let it run for more then a few sec., if the charge is low or system is empty, the refrigerant oil, [compressor lubricant] is not circulating, the result, to compressor, is the same as running the cars engine without oil.
hey fcm! i’m confused when you say “hot in run” - i’m assuming dont pull fuse 17 out when running the car? do i have to disconnect the battery before pulling that specific fuse or just dont start the car and pull the fuse to inspect it?
Hot at all times = live even when ign. key is off.
Hot in run = live when ign. key is in the acc. and run position.
Hot in acc. and run = live when ign. key is in acc. and run position.
Hot in run and start = live when ign. key is in acc. run and start position.
Hot in start = live only when key is in start position.
Fuses can be pulled anytime, although some fuses need to be on place for car to run, pulling those fuses can not hurt anything, just stall the engine.
Batt. does not need to be disconnected to pull fuses. 94
wow, that was fast! thanks for your knowledge, i’m sure all members on the site greatly appreciate it as i do!!!
Anyone know exactly where the pressure switch is?? I am trying to test it, but I can’t find it. There are two plugs next to the battery that each have two wires. One is white plug the other plug is green. Looks like the green plug runs down to the radiator fan. Also where is the A/C Compressor clutch relay? I’d like to test that too. Is it in the underhood fuse box, or somewhere else?? Any pics would sure help out. Thanks.