94 regal a/c stops & starts

Hi all, I just recently bought a 1994 buick regal gs 3.8 for my daughter. The air conditioning wasn't working. I tried charging the system but it only needed a few pounds of freon. After i put some freon in i noticed when you start the car the compressor would kick in for a second then kick out. It would do that for three maybe 4 times then the clutch would stop trying to engage. I changed out the relay for the compressor and it made no difference. The clutch kicks in then out 3 or 4 times then stops trying to engage. Any and all suggestions to remedy the situation will be most appreciated. thank you.

Only a few pounds?

What is the capacity on the A/C label?

Does the accumulator have a pressure cycling switch on it?

Does the engine cooling fan run when the A/C clutch engages?

You say you have added a few pounds to the system, so I don't think the compressor is short cycling because of low freon.....however, it could be overcharged, and is shutting down, or pressure is building up because the cooling fan is not running......when the PCM sees the compressor short cycling, it will disable it....code may be set in the PCM....

Need to get a set of gages on this puppy and see what you have on the low and high side when the clutch engages, and also see if the the cooling fan enages to lower high side pressure....

Only a few pounds?

What is the capacity on the A/C label?

Does the accumulator have a pressure cycling switch on it?

Does the engine cooling fan run when the A/C clutch engages?

You say you have added a few pounds to the system, so I don't think the compressor is short cycling because of low freon.....however, it could be overcharged, and is shutting down, or pressure is building up because the cooling fan is not running......when the PCM sees the compressor short cycling, it will disable it....code may be set in the PCM....

Need to get a set of gages on this puppy and see what you have on the low and high side when the clutch engages, and also see if the the cooling fan enages to lower high side pressure....

Hi, thanks for the reply
the system according to the tag holds 2 lbs of freon

I don't know what a pressure cycling switch is

there are two fans on the inside of the radiator. the one on the drivers side runs when the engine warms up. I have never seen the passenger side fan run

when i first hooked up the a/c recharge kit it showed 32 lbs. according to the instructions the outside temp was 89 degrees so it required the a/c to be charged to 45 to 55 pounds

so if the fan is not running on the drivers side that could cause the air not to work?
what if i switched the fans, driverside to passenger side and vice versa.

if the shut down is in the PCM does it have to be cleared before it will work
i don't know much about air conditioning. thank you

I pulled the passenger side fan out and hot wired it and the fan ran. Its 94 degrees out and when i just tried the a/c again the clutch on the compressor did not kick in at all, not even for a second.:mad:

There is a pressure switch in the accumulator (or the low pressure line) and another on the high pressure line, commonly in the compressor itself. The low and high side pressure switches and compressor status are reported to the ECM, and the ECM uses this status and the engine coolant temperature and vehicle speed sensor to determine whether the secondary fan will operate.

The ECM operates a fan relay to run the secondary fan motor. The circuit receives power from a 60A MAXI fuse in the fuse/relay panel under the hood. Since the primary fan uses an identical relay you should be able to exchange the two relays to determine if the relays are intact. You should also be able to inspect and/or meter the fuses to determine if they are intact.

The low- and high-pressure switches also dictate whether the compressor will operate. Since you previously had the compressor cycling briefly we can presume the compressor relay and fuse for the compressor are intact. Thus, there is likely a problem with the pressure switches. You can measure the continuity (resistance) of the low pressure switch to make sure it is closed, and/or briefly jumper the switch connector in the wire harness to see if the compressor will operate.

If the compressor does not operate with the controls at max cold and the low side pressure switch jumpered, there is a chance the high pressure cycling switch is preventing the compressor from running. The high pressure cutout switch (likely on the rear of the compressor) can be difficult to access for measurement, but if there is no other problem indicated you may have to access and test the switch continuity. It is NOT advisable to jumper the high pressure switch since doing so can create dangerously high system pressures, potentially causing personal injury and/or equipment damage.

If the high pressure cutout is preventing compressor operation it could be due to a faulty switch, system overcharge, or a restriction in the system such as a plugged orifice tube in the evaporator inlet or plugged condenser. The best way diagnose the system will be to connect pressure gauges to both the low and high sides of the system so you have some indication of the actual conditions.

There is a pressure switch in the accumulator (or the low pressure line) and another on the high pressure line, commonly in the compressor itself. The low and high side pressure switches and compressor status are reported to the ECM, and the ECM uses this status and the engine coolant temperature and vehicle speed sensor to determine whether the secondary fan will operate.

The ECM operates a fan relay to run the secondary fan motor. The circuit receives power from a 60A MAXI fuse in the fuse/relay panel under the hood. Since the primary fan uses an identical relay you should be able to exchange the two relays to determine if the relays are intact. You should also be able to inspect and/or meter the fuses to determine if they are intact.

The low- and high-pressure switches also dictate whether the compressor will operate. Since you previously had the compressor cycling briefly we can presume the compressor relay and fuse for the compressor are intact. Thus, there is likely a problem with the pressure switches. You can measure the continuity (resistance) of the low pressure switch to make sure it is closed, and/or briefly jumper the switch connector in the wire harness to see if the compressor will operate.

If the compressor does not operate with the controls at max cold and the low side pressure switch jumpered, there is a chance the high pressure cycling switch is preventing the compressor from running. The high pressure cutout switch (likely on the rear of the compressor) can be difficult to access for measurement, but if there is no other problem indicated you may have to access and test the switch continuity. It is NOT advisable to jumper the high pressure switch since doing so can create dangerously high system pressures, potentially causing personal injury and/or equipment damage.

If the high pressure cutout is preventing compressor operation it could be due to a faulty switch, system overcharge, or a restriction in the system such as a plugged orifice tube in the evaporator inlet or plugged condenser. The best way diagnose the system will be to connect pressure gauges to both the low and high sides of the system so you have some indication of the actual conditions.

thank you for the reply. I will try the low pressure switch jumper.

Right below the air filter is the place where the high side and low side hookups are. right next to the high side and low side connectors is what looks like a switch. both of them has what looks like a switch with two wires coming out of them. again thank ou for the information

Hi all again. Okay, I took the air cleaner box out to get access to the high and low switches. the small line(high side) has the switch in line. the thick pipe (low side) goes into one side of a round canister and out the other side. in between the two pipes,one in and one out of the canister is a two wire plug which i am assuming is the low pressure switch. i started the car, turned the a/c to max and fan on high. I pulled the plug from the low pressure switch and put a jumper wire onto the two wires. The a/c compressor clutch did not activate. Anyone have any ideas as to whats up? thanks

Got the a/c working. put it on defrost and the compressor started kicking on and off. took the low pressure plug off and put a jumper wire on it. the clutch engaged the compressor. put the ac pro on and put in freon. it is now running and colder than my 2009 ford F150's air. thank you all for the information and tips.

I am having exactly the same problem with exactly the same car. Can you be more specific on what you did to fix it?

I am having exactly the same problem with exactly the same car. Can you be more specific on what you did to fix it?

Hi.You have to take the airbox out to access the lowside two wire pressure switch and plug. Once you have the switch located unplug it. Take a wire (i used a 12 gauge wire) and jump the two wires in the plug. Start the car (have your charging hose and can connected) and put the fan on high and defrost on. The compressor clutch should engage. Once it engages start putting freon in. Charge it to the recommended pressure and your done.

No luck. Following that procedure, here are my results:

The compressor engaged and ran constantly, never making the components of the low-side cold as they should be. The pressure on the low side read zero or near zero the whole time. I found that I could make the compressor cycle by jumping/not jumping/jumping etc. Still, no cold air, no cold parts.

There was one thing I did not do, and that was to add so much refrigerant that the low-side reads at the recommended pressure while the compressor is running. They way you wrote your last message, it seems this is what you recommended.

I don't know too much about a/c, but I thought the recommended pressure was what should be in the system when it is not functioning. For today's weather I need to make the system read between 45 and 50 psi. While the compressor was running, and after I added some refrigerant to the system, it still read perhaps as much as two or three psi. When the compressor is not running it reads just above 60 psi.

I'm worried about overcharging the system so much that components begin to leak, seals begin to blow, and/or parts simply rupture on the high-side. Should I add more refrigerant so it reads the recommended pressure WHILE the compressor is running?

:banghead:

No luck. Following that procedure, here are my results:

The compressor engaged and ran constantly, never making the components of the low-side cold as they should be. The pressure on the low side read zero or near zero the whole time. I found that I could make the compressor cycle by jumping/not jumping/jumping etc. Still, no cold air, no cold parts.

There was one thing I did not do, and that was to add so much refrigerant that the low-side reads at the recommended pressure while the compressor is running. They way you wrote your last message, it seems this is what you recommended.

I don't know too much about a/c, but I thought the recommended pressure was what should be in the system when it is not functioning. For today's weather I need to make the system read between 45 and 50 psi. While the compressor was running, and after I added some refrigerant to the system, it still read perhaps as much as two or three psi. When the compressor is not running it reads just above 60 psi.

I'm worried about overcharging the system so much that components begin to leak, seals begin to blow, and/or parts simply rupture on the high-side. Should I add more refrigerant so it reads the recommended pressure WHILE the compressor is running?

:banghead:

you need to charge it when the compressor is running to the recommended pressure.