ac gremlins

vr4gto · 07-15-2012, 09:05 PM

It's freakin hot and my AC hates me in my 97 GS. It works just fine at idle, cold as Lake Superior mid January. But when I start to drive the condensor fan and radiator fan shut off and the green light flashes on my AC button. Hooked a gauge to the low side and it reads 35 psi. Clutch is engaging and stays engaged when the fans shut off. Any help is super appreciated.

masterjonny · 07-15-2012, 09:23 PM

check that sensor under the thermostat housing.... try unplugging and clean it and plug it back in

vr4gto · 07-16-2012, 03:49 PM

Quote:

Originally Posted by masterjonny

check that sensor under the thermostat housing.... try unplugging and clean it and plug it back in

I don't see anything wrong with it. Isn't that the coolant temp sensor? What does it have to do with the AC?

I hooked a gauge up to the low side and it reads super high above 3k rpm then shuts off the fans but the compressor still runs. Any ideas?

masterjonny · 07-16-2012, 09:37 PM

idk for some reason i did what i told u and it worked after lmao

vr4gto · 07-18-2012, 03:29 PM

I suppose if the AC clutch is bad it will shut the system off as well right? It looks like the pulley is wobbly.

stars · 07-18-2012, 05:25 PM

Low side should be around 39 and High side should be around 150-200 at 1500 RPM's. Make sure its within those specs and you will have nice ice cold A/C. Normally any spikes in pressure means your compressor is going bad internally or you have over charged the refrigerant or the condenser has a restriction. With your condenser fan shutting off the, High Pressure switch is seeing too much of an increase in pressure and for your safety is is shutting the fans off to the condenser. If the clutch on the compressor is going bad it will not engage and the compressor will not work, period. Now, sometimes the clutch gets weak and if it is shimmed you can take one of the shims off and the clutch will work properly. That is if you can pull the hub off of the compressor clutch and check if has shims but, at this point with the Low side spiking I think you will need to replace that compressor if you have not over charged the refrigerant.

vr4gto · 07-18-2012, 06:06 PM

Well I know the system isn't overcharged. It is at about 35psi. When I rev over 2500 tpms the pressure on the gauge spikes super high and then the fans shut off. How would I find a restriction in the system?

stars · 07-18-2012, 06:48 PM

Does your gauges have a Low and High side? Are you using just one single gauge? It is important to know what the numbers are on both sides of the compressor in order to diagnose a A/C problem. Just by knowing those values on the Low and High side gauge readings will let you know what is going on within the system when it is operating. In terms of a restriction that is difficult to tell without knowing what your High side and Low side pressures are respectively. If there is any pressure over 200 on the High side you can expect a blockage in the condenser, sometimes the receiver drier will burst and spill its contents into the system.

If your just using one single gauge connected to the Low side suction port then your best to take it to a shop and let them do a diagnosis and then you perform the repair based off their findings. If your Low side gauge is going past 39 then that leads me to believe based on your reading from the Low side that the High side is bleeding back pressure to the Low side which means that the compressor is going bad internally, there is no way to know for sure until you know what the High side of the compressor is reading versus the Low side pressure readings.

wrencher · 07-18-2012, 08:45 PM

These N/T's are a little different, they use a nippendenso 10 cylinder with a compressor RPM sensor for the ACCU.
If it's flashing there's a fault, I mention the RPM sensor because of your symptoms.

But everything will have to be checked with the ACCU (a/c control unit).
All the input sensors. But of course the proper charge amount would be the first thing to check.

It has to be disengaging the clutch when the light flashes.
Does it do the same @ a stop with the engine @ 2500 RPM?

If so the first input sensor you might wanna check is the RPM sensor in the compressor.
You can ohm them out 185 ohms @ 68 degrees is the only spec on it.

vr4gto · 07-20-2012, 08:08 AM

I had a gauge on the low side only. The pressure would spike about 2500 rpm's whether driving or at a stop and bringing the R's up. It does look like the compressor pulley is wobbly and I hear a grinding noise when the AC is on.

stars · 07-20-2012, 10:11 PM

I would say by your observation that the compressor is going to fail at some point in time. To be sure though it would be nice to know what the Low and High sides are reading, but since you have only 1 gauge and you have done an adequate visual inspection, it would be safe to assume and I do not like to assume but, in this case guess I will have to; is that the compressor is failing internally. Given the fact you have seen that the Low side spikes to way above normal, I would suggest that you get another compressor and go from there. That's the last logical solution at this point; as you already know you have the proper amount of refrigerant in the system and it is till not functioning properly as it should be.

vr4gto · 07-22-2012, 11:36 PM

When I replace the compressor, what is the proper way on releasing the refridgerant from the system?

TBoxdorfer · 07-26-2012, 08:13 PM

It's possible the clutch is bad, not compressor. Although a compressor should come a clutch it may not need it. Typically a compressor rattles or knocks when going bad, a clutch schreeches due to metal to metal slippage. If ## luck I can remove the clutch and adjust it tighter. I have done that many times on various vehicles.