2003 Silverado With Ac Issues

nickbartels · July 23, 2011

I am having issues with the AC on my truck, and it just up and quit on me today. For a couple years now the AC has been cycling on/off. Sometimes it wouldn't come back on until I thumped the low pressure cycle switch on the accumulator. I replaced the switch with a new one from Chevy. Still cycled on/off but at least I didn't need to thump it anymore.

Recently a family friend threw a set of gauges(I have since purchased my own set of yellow jacket gauges) on the it to see if we could determine the issue or at least see if it was low. I believe it read 45psi (low side) and 225psi (high side). He checked with his HVAC buddy and it was decided it was low. We added a can of freon and it now read 60/275. It still cycled on/off. However after adding the can, the temp at the center vent was 45-55 degrees(depending on the day and if I was at idle or cruising down the road).

Since it was still cycling, I put my gauges on to start the troubleshooting process, on a 95 degree day in the sun. At idle, I had 60psi low, 300psi high, center vent was 50 degrees. I held it at 2000RPM and it started cycling. In just about 4 seconds it would go from 60psi to 30psi on the low side and cycle off. The high side didn't really jump up or down when this happened. It would start to equalize the pressure(another 4 seconds) and would cycle on when the low side got to 70psi. Then the process started all over again. Returning to idle would stabilize the pressures(at least until it went above idle again. Going down the interstate, I can tell it was still cycling on/off. I could feel the temp of the air change coming out of the vents, and the timing was about the same as I experienced sitting in the driveway with the gauges connected.

Well...Today it just stopped altogether...I thumped the low pressure switch, nothing. I jumpered the low pressure switch and it came back to life, kind of. Low side reads 65psi and high side roughly 300-325psi. The temp at the center vent is about 65-70 at idle and about 60 at 1500-2000RPM. Currently 95 degrees outside.

ANY help would be appreciated. I fear I will be replacing some expenses parts, but hey, its just money right?

Thanks in advance!

Nick

exracer · July 23, 2011

you sure on the low side pressure?.....that seems too high?....I thought about 35 to 40 was about right

wavery · July 23, 2011

I am having issues with the AC on my truck, and it just up and quit on me today. For a couple years now the AC has been cycling on/off. Sometimes it wouldn't come back on until I thumped the low pressure cycle switch on the accumulator. I replaced the switch with a new one from Chevy. Still cycled on/off but at least I didn't need to thump it anymore.

Recently a family friend threw a set of gauges(I have since purchased my own set of yellow jacket gauges) on the it to see if we could determine the issue or at least see if it was low. I believe it read 45psi (low side) and 225psi (high side). He checked with his HVAC buddy and it was decided it was low. We added a can of freon and it now read 60/275. It still cycled on/off. However after adding the can, the temp at the center vent was 45-55 degrees(depending on the day and if I was at idle or cruising down the road).

Since it was still cycling, I put my gauges on to start the troubleshooting process, on a 95 degree day in the sun. At idle, I had 60psi low, 300psi high, center vent was 50 degrees. I held it at 2000RPM and it started cycling. In just about 4 seconds it would go from 60psi to 30psi on the low side and cycle off. The high side didn't really jump up or down when this happened. It would start to equalize the pressure(another 4 seconds) and would cycle on when the low side got to 70psi. Then the process started all over again. Returning to idle would stabilize the pressures(at least until it went above idle again. Going down the interstate, I can tell it was still cycling on/off. I could feel the temp of the air change coming out of the vents, and the timing was about the same as I experienced sitting in the driveway with the gauges connected.

Well...Today it just stopped altogether...I thumped the low pressure switch, nothing. I jumpered the low pressure switch and it came back to life, kind of. Low side reads 65psi and high side roughly 300-325psi. The temp at the center vent is about 65-70 at idle and about 60 at 1500-2000RPM. Currently 95 degrees outside.

ANY help would be appreciated. I fear I will be replacing some expenses parts, but hey, its just money right?

Thanks in advance!

Nick

Might be a bad compressor clutch coil.........

Sorta shooting in the dark but I'd start checking electrical.

nickbartels · July 24, 2011

you sure on the low side pressure?.....that seems too high?....I thought about 35 to 40 was about right

I honestly don't know the correct pressures for my truck, haven't figured that out yet. I do know that the low pressure cycle switch cuts out at 30psi, so I would imagine the correct pressure would be more than 5-10psi above the cut off. But like I said, I don't know the correct numbers. If someone does know the correct pressures, please let me know!

Thanks

nickbartels · July 24, 2011

I am having issues with the AC on my truck, and it just up and quit on me today. For a couple years now the AC has been cycling on/off. Sometimes it wouldn't come back on until I thumped the low pressure cycle switch on the accumulator. I replaced the switch with a new one from Chevy. Still cycled on/off but at least I didn't need to thump it anymore.

Recently a family friend threw a set of gauges(I have since purchased my own set of yellow jacket gauges) on the it to see if we could determine the issue or at least see if it was low. I believe it read 45psi (low side) and 225psi (high side). He checked with his HVAC buddy and it was decided it was low. We added a can of freon and it now read 60/275. It still cycled on/off. However after adding the can, the temp at the center vent was 45-55 degrees(depending on the day and if I was at idle or cruising down the road).

Since it was still cycling, I put my gauges on to start the troubleshooting process, on a 95 degree day in the sun. At idle, I had 60psi low, 300psi high, center vent was 50 degrees. I held it at 2000RPM and it started cycling. In just about 4 seconds it would go from 60psi to 30psi on the low side and cycle off. The high side didn't really jump up or down when this happened. It would start to equalize the pressure(another 4 seconds) and would cycle on when the low side got to 70psi. Then the process started all over again. Returning to idle would stabilize the pressures(at least until it went above idle again. Going down the interstate, I can tell it was still cycling on/off. I could feel the temp of the air change coming out of the vents, and the timing was about the same as I experienced sitting in the driveway with the gauges connected.

Well...Today it just stopped altogether...I thumped the low pressure switch, nothing. I jumpered the low pressure switch and it came back to life, kind of. Low side reads 65psi and high side roughly 300-325psi. The temp at the center vent is about 65-70 at idle and about 60 at 1500-2000RPM. Currently 95 degrees outside.

ANY help would be appreciated. I fear I will be replacing some expenses parts, but hey, its just money right?

Thanks in advance!

Nick

Might be a bad compressor clutch coil.........

Sorta shooting in the dark but I'd start checking electrical.

I considered that, however I would think it would cycle at idle also...

teknition · August 1, 2011

I am having issues with the AC on my truck, and it just up and quit on me today. For a couple years now the AC has been cycling on/off. Sometimes it wouldn't come back on until I thumped the low pressure cycle switch on the accumulator. I replaced the switch with a new one from Chevy. Still cycled on/off but at least I didn't need to thump it anymore.

Your a/c has been cycling on/off since it was new. The Chevy truck a/c system is a CCOT type system which stands for cycling clutch orifice tube. In short that means the clutch is meant to cycle on/off. When you thump the cycling switch you could have found a bad switch, but I have found most problems with the switch in these systems is in fact the wiring pigtail at the switch. Try wiggling the wiring connector at the switch with the a/c on if your quits completely again.

Recently a family friend threw a set of gauges(I have since purchased my own set of yellow jacket gauges) on the it to see if we could determine the issue or at least see if it was low. I believe it read 45psi (low side) and 225psi (high side). He checked with his HVAC buddy and it was decided it was low. We added a can of freon and it now read 60/275. It still cycled on/off. However after adding the can, the temp at the center vent was 45-55 degrees(depending on the day and if I was at idle or cruising down the road).

When you are checking your a/c pressures, read both pressures just before the compressor cuts out. Low side pressure doesnt really mean much as it should consistantly cut out at approx 30 psi (switch cutout pressure). The only time it is relevant is when it is doing something other than that.

Since it was still cycling, I put my gauges on to start the troubleshooting process, on a 95 degree day in the sun. At idle, I had 60psi low, 300psi high, center vent was 50 degrees. I held it at 2000RPM and it started cycling. In just about 4 seconds it would go from 60psi to 30psi on the low side and cycle off. The high side didn't really jump up or down when this happened. It would start to equalize the pressure(another 4 seconds) and would cycle on when the low side got to 70psi. Then the process started all over again. Returning to idle would stabilize the pressures(at least until it went above idle again. Going down the interstate, I can tell it was still cycling on/off. I could feel the temp of the air change coming out of the vents, and the timing was about the same as I experienced sitting in the driveway with the gauges connected.

4 second cycle time indicates the system is probably still a bit on the low on refrigerant. 45-55 degrees on a 95 degree day isnt all that bad actually, but you should be able to get it down to the 40 degree area.

Well...Today it just stopped altogether...I thumped the low pressure switch, nothing. I jumpered the low pressure switch and it came back to life, kind of. Low side reads 65psi and high side roughly 300-325psi. The temp at the center vent is about 65-70 at idle and about 60 at 1500-2000RPM. Currently 95 degrees outside.

Again, wiggle the pigtail and see if the compressor kicks in. If so, replace the pigtail. If not, by jumpering the low pressure switch and getting the compressor to engage, you have eliminated numerous possibilities. Your problems are on of the following:

1- system is empty. (obviously not by those pressures)

2- bad pigtail connection at the switch ? (my bet)

3- defective cycling switch ?

Check those 3 things and one of them will get you back to a working, cycling system. From there, judging by what you have said, I would say the system needs a liitle more refrigerant. Try adding 1/4 lb. at a time until your vent temp comes down to 40 degrees. (windows up, on recirculate, thermometer stuck in the vent so you can read it without opening the doors) Add 1/4 lb and then let the system run for 5-10 minutes and check the temp. There is no magic pressure number that the system should be at. Pressures will change with ambient air temp and you will only get a rough idea of what those pressures are after working on a/c systems for a few years.

You have added one can so far (1 lb.) check the system capacity on the sticker on the accumulator and dont exceed that quantity. A system that is over charged is much worse than under charged. if you start adding 1/4 lb at a time and checking temp, it should always go down in temp. If it starts to go up in temp, you are overfilling the system.

ANY help would be appreciated. I fear I will be replacing some expenses parts, but hey, its just money right?

Thanks in advance!

Nick

Good luck Nick, let us know how it turns out.

Brad

arwriter · January 2, 2012

I have a '99 Silverado 2500 with the 6.0 V8. My a/c has stopped working altogether. I had the system re-charged with dye added and within 2 days it was not blowing cold again. I conducted a visual inspection and found the compressor covered in dye where the freon was leaking. Prognosis: a/c compressor is bad.

The estimate from the auto shop to replace it came in at a painful $1,193. This includes replacing the accumulator as it is strongly recommended that it be replaced when the compressor is, as well as the orifice tube. I do not have the equipment to de-pressurize and dispose of the freon, so I cannot conduct these repairs on my own (plus I haven't done it before and don't want to create new problems in the process).

I still need to call the chevy dealership and see what their estimate is, but does $1,193 sound like an average price to do this work? The shop I took it to was recommended to me as a respectable place and they conduct themselves very professionally.

Please someone with more experience weigh in.

tesnoboy · January 2, 2012

^{The price sounds about right. AC components and work is expensive. Why are you worried about fixing AC this time of year? Is it that warm still in NC?You have plenty of time to save up before Summer. Mine is also broken. These old GM vehicles have plenty of AC problems.}