A/C compressor clutch issue?
08-23-2015, 12:50 PM
#1
Thread Starter
A/C compressor clutch issue?
So I just got back from being out of town for two weeks, and I'm having a funny issue with the air conditioning, which worked perfectly till now. The air would blow cold and then halfway through my drive, I noticed it heating up. After having it off for a bit, I turned it on again and it exhibited the same behavior. The following day it wouldn't blow cold at all. I assumed that it might be a low refrigerant issue, with the car being 14 years old and just recently having sat for two weeks, so I had the system evacuated and it held vacuum, so no leaks. Upon recharging the system, I managed to get 6-10 oz of refrigerant back in the system before it felt like it wasn't taking any more. The compressor clutch was still stationary. I checked the three relays in the under hood fuse box, all seemed functional, but just in case, I switched them around, and both radiator fans worked no matter how the relays were arranged, but the compressor clutch still wouldn't engage. With the vehicle off, I was able to spin the clutch freely by hand. Is there anything else that I overlooked? How would one test the function of the clutch or the compressor? Sorry for the wall of text, and thanks in advance.
08-23-2015, 01:01 PM
#2
What kind of pressure are you seeing in the system. A system that old is probably due for at least a new drier and possibly a new expansion valve.
08-23-2015, 01:15 PM
#3
Thread Starter
Before evacuating the system, had 150 ish on both sides (high/low), but the compressor wasn't running when I was able to get those measurements. After holding vacuum at -30psi? for an hour, I attempted to recharge. The low side got to 100 or so psi before the can didn't seem to want to put any more in, and of course the compressor still wouldn't kick on.
08-23-2015, 02:57 PM
#4
Take off your radiator cap with a cold engine. Is the coolant level up to the top? Just a hunch. Years ago I had the same symptoms with another car. It had a small head gasket leak and the first symptom was the A/C kicking off with a warm engine. The head gasket leak prevented the radiator from sucking fluid from the reservoir. A faulty rad cap or disconnected reservoir siphon tube can cause this too.
08-23-2015, 03:06 PM
#5
^ The A/C system is completely separate from the cooling system...
A system can be fully charged but if you have a faulty clutch/field coil or a bad thermal protector, the system won't engage.
A system can be fully charged but if you have a faulty clutch/field coil or a bad thermal protector, the system won't engage.
08-23-2015, 04:25 PM
#6
Thread Starter
Take off your radiator cap with a cold engine. Is the coolant level up to the top? Just a hunch. Years ago I had the same symptoms with another car. It had a small head gasket leak and the first symptom was the A/C kicking off with a warm engine. The head gasket leak prevented the radiator from sucking fluid from the reservoir. A faulty rad cap or disconnected reservoir siphon tube can cause this too.
coolant levels are fine, no head gasket issues.
08-24-2015, 06:05 AM
#7
There's a couple things, system is either overcharged, and the thermal protector is doing it's job, or there's an electrical problem. Sometimes an expansion valve goes bad and causes the symptoms you originally had. If the system has excess moisture or if the valve is slightly stuck open, the valve can freeze shut and will stop blowing cold air out of the vents. Sometimes this can burn out the thermal protector to preserve the compressor.
If the thermal protector is bad you can replace it I would also replace the drier and expansion valve if indeed the thermal protector went out. At least based on your symptoms.
Field coil should show slightly over 3ohms at room temperature. There should be continuity from field coil to thermal protector.
I'm sure you checked all the fuses as well? Also an overheating car WILL affect ac operation. Even a bad TPS will affect it.
Jumping pins 1&2 on the 4pin ac relay should make the clutch click on.
Hope this helps.
If the thermal protector is bad you can replace it I would also replace the drier and expansion valve if indeed the thermal protector went out. At least based on your symptoms.
Field coil should show slightly over 3ohms at room temperature. There should be continuity from field coil to thermal protector.
I'm sure you checked all the fuses as well? Also an overheating car WILL affect ac operation. Even a bad TPS will affect it.
Jumping pins 1&2 on the 4pin ac relay should make the clutch click on.
Hope this helps.
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08-24-2015, 06:18 AM
#8
08-24-2015, 05:14 PM
#9
My understanding is that the A/C will not kick on (or will kick off) if the A/C radiator can't cool the Refrigerant enough. If the coolant radiator is low, the coolant temps rise due to less heat transfer and the air passing through the radiator gets much hotter. That makes it harder for the refrigerant to adequately cool down. Keep in mind that the radiator fan blows air through the coolant radiator first, then through the A/C radiator.
08-26-2015, 05:39 AM
#10
Thread Starter
There's a couple things, system is either overcharged, and the thermal protector is doing it's job, or there's an electrical problem. Sometimes an expansion valve goes bad and causes the symptoms you originally had. If the system has excess moisture or if the valve is slightly stuck open, the valve can freeze shut and will stop blowing cold air out of the vents. Sometimes this can burn out the thermal protector to preserve the compressor.
If the thermal protector is bad you can replace it I would also replace the drier and expansion valve if indeed the thermal protector went out. At least based on your symptoms.
Field coil should show slightly over 3ohms at room temperature. There should be continuity from field coil to thermal protector.
I'm sure you checked all the fuses as well? Also an overheating car WILL affect ac operation. Even a bad TPS will affect it.
Jumping pins 1&2 on the 4pin ac relay should make the clutch click on.
Hope this helps.
If the thermal protector is bad you can replace it I would also replace the drier and expansion valve if indeed the thermal protector went out. At least based on your symptoms.
Field coil should show slightly over 3ohms at room temperature. There should be continuity from field coil to thermal protector.
I'm sure you checked all the fuses as well? Also an overheating car WILL affect ac operation. Even a bad TPS will affect it.
Jumping pins 1&2 on the 4pin ac relay should make the clutch click on.
Hope this helps.
Unfortunately I've been busy and haven't had a chance to check these things out, I plan on testing some of the possible electrical issues today with a multimeter. About the clutch relay, if I jump those pins will it by bypass any of the safeties in place that might be preventing the clutch from engaging in the first place? Which two pins are the ones I should jump? Also, I checked all fuses that looked like they apply, they really looked like they just were for the engine bay fans and in cabin hvac controls though.