Hi,
My GF's car, a 99 Buick Century Custom with the 3.1l V6 engine has got AC issues.
At first no air was coming out of the vents. I had a look at the fuses and the blower motor fuse was bad, I replaced it but the blower was now making squeaky noises. Playing around with it changed the pitch of the noise so I replaced the blower motor and now the vents blow just fine. Every speed works and setting air to hot blows hot air.
So I took it under the hood and I observed the electrical connection going to the AC coil was ripped. I replaced the connector and measured with the multimeter 12v going to the coil. But still, it isn't working.
The compressor clutch spins freely with my hand so it doesn't seem locked up. I checked the under the hood AC compressor fuse and it's good.
I've checked the relay and it seems good as well. What I've done is that I've used a paperclip method in order to force the compressor clutch to kick in but unfortunately, it still doesn't want to be on.
Meaning that at this point:
- the blower works
- the interior and under the hood fuses and relays are fine
- The dash panel dials work as well
- Cabin air filter is new
- I have 12 volts going to the coil and the connection is good.
- Condenser looks to be in good condition
I haven't been able to add refrigerant because the compressor won't kick in.
Checking with my (inexpensive) scan tool, I only have a P449 error code for some EVAP thing so nothing related to the AC.
I'm unsure where to go from there in order to get the AC to work again.
Any help is appreciated.
Thank you for reading and God bless from Clarksville, TN
Before adding any R134a to the ac system get yourself a set of gauges and check the static pressure (engine off) of the AC system.
R134a temperature to pressure scale is close to the fahrenheit temperature scale.
Meaning, on an 85 degree day the R134a static pressure will be about 85 psi. That won't tell you if your system is completely charged but it will tell you that there's enough refrigerant in the system that the compressor clutch should be engaging.
But that doesn't matter yet because when you jumped the AC Clutch relay sockets 30 & 87 you should have been able to hear the AC Clutch "click" as it was being engaged and you didn't hear it. So there's a problem on the Load Side of this circuit.
Next you can grab a test light. Attach the alligator clip to Battery Negative and touch the test light's probe to relay socket 30.
The test light will light up if there's power there.
Then switch the test light's alligator clip to Battery Positive and touch the test light's probe to relay socket 87.
The test light will light up if there's no Open in the wiring going to the ac compressor clutch or an Open in the windings of the ac compressor clutch.
The compressor clutch spins freely with my hand so it doesn't seem locked up.
Did you rotate the clutch plate which is attached to the compressor crank, or just the clutch pulley?
I have 12 volts going to the coil and the connection is good.
Did you check the coil for continuity or shorts? If it's getting 12 volts and not engaging chances are the coil is bad.
I haven't been able to add refrigerant because the compressor won't kick in.
How do you know it needs refrigerant?
Attached is a picture of the compressor. I have only tried so far to rotate the part displayed as number 1, so I am guessing it is solely the plate that's on the left of the belt.
If the belt was on and you were able to rotate the plate then you were turning the compressor crank and it's not locked up.
I haven't checked the coil for continuity or shorts, could you please teach me how to do so?
Just use an ohm meter. Though if the coil is not generating a magnetic field when 12 volts is applied it's not working.
As for the refrigerant, I figured it would be the next logical step as the AC on this car hasn't been running in 4 years apparently
It may well need refrigerant but you don't just blindly add it. You also should not use one of those useless and potentially damaging so-called "recharge cans" available at so many parts stores and other retail outlets.
First you should hook up a manifold gauge set to see if there's enough static pressure in the system for the low-pressure safety cutoff to even permit the compressor to engage. Once the compressor is running the system pressures can be checked for indications of problems.
The only way to really be sure you have the right amount of refrigerant is to evacuate and recharge the system. Especially with a variable-displacement compressor you cannot judge refrigerant level by system pressures. With R134a the refrigerant load is critical, it is not as forgiving as R12a was. (What you can sometimes get away with if you're careful is to add a little bit of refrigerant a time while watching system pressures.)
I don't have much knowledge so bear with me.
No offense, but if you have no experience with AC systems it is very easy to make things worse, cause damage, or even injure yourself. Go ahead and check the basics but if that air conditioner needs real work take it to a professional.
https://www.youtube.com/watch?v=_IBFLMYZEzI
https://www.youtube.com/watch?v=0HCSsv3uYfM
Hi, thank you for your quick reply.
Attached is a picture of the compressor. I have only tried so far to rotate the part displayed as number 1, so I am guessing it is solely the plate that's on the left of the belt. https://imgur.com/4owFW0d
I haven't checked the coil for continuity or shorts, could you please teach me how to do so?
As for the refrigerant, I figured it would be the next logical step as the AC on this car hasn't been running in 4 years apparently
I don't have much knowledge so bear with me. I appreciate your time.
Hey,
I haven't had time to really work in great details but I did a quick measurement and I have continuity from the pin 87 to the positive battery terminal but I don't have continuity from pin 30 to the battery negative.
Thank you for your help