not sure if this is the right place for this, but here goes
my AC quit working today, has 194,000kms on truck, worked fine last year, used it quite a bit.
need some advice, or info on this, or any body with the same problem could point me in the right direction.
turned AC on today while driving on the high way, worked for about 5 mins then went warm.turned it off, move the selector switch around and the hot to cold slide , put back to coldest, and back to upper dash vents, turn back on, with recir. and work for another 3-4 mins then went warm. shut system down, about 1 hours later turned back on, worked 5 mins then went warm.
and so on.took it into the chevy dealer where my buddy works, had him check for pressures, high side is about 200, and the low side around 30-35, 134a was about 1.36lbs, and should be about 1.80lbs. so he recovered the system, and re installed 134a, with dye.turned AC on , was cold for about 5-7 mins, speed up idle alittle , went a bit colder, then pulled it out of shop, went warm again. the condensor was a little warmer on the inlet side of piping, looks to be ok, not damaged, no signs of bad leakage, but i did notice the compressor was cycling a lot more then what i am use to,seems to come on for about 30 sec, the off, and repeats that. i am pretty sure the clutch would engage, for more like 1-3 mins before cycling off when the AC was first turned on in the day.can't remember what the cycling period was when it was colder in the truck, because usually driving by then. seems that it works better at idle then it does while driving.i use the windshield defrost in the winter quite often to cycle the compressor,to keep things moving.
not sure where to go at this point, so what are the common problems with these trucks in the AC system?
pressure switch?
evap canister
dryer?
anybody had problems with thier system and knows what it could be by my symptoms????
any help would be great.

 

I would check to make sure the compressor clutch is engaged when the A/C stops working. If not engaged first thing to check is the pressure switch.
These trucks seems to be very sensitive to the R134 level. Might also try going slightly above spec on the pressure and capacity.
Also check the connections on the backside of the HVAC controller.

MikeyB

 

You might try and run a jumper from the battery to the compressor clutch connection thereby bypassing the switch. If the clutch is engaged and the compressor running but the system not blowing cool air or reduced air flow your evaporator may be freezing up in the cab.

Does the air stay cooler longer when you first start the truck after it has set for a long period of time so the coolant temperature is the same as the outside temperature? I believe there is an air door that allows some air to pass through the heater core that could be defective allowing warm air to mix with the cool air when you have the temperature **** turned fully counterclockwise to the coldest setting.

Good luck. L8r,..........dogger

 

the compressor engages and dis engages(cycles) even when the cold air stop coming. i don't lose any air volume, and i know when it has stopped moving cold air as you get that musty smell of the warm air replacing the cold ac air.
it is like some one just shut off the air but kept the fan speed up.the ac button on the dash stays lit, and it don't matter if it is on recirc. or not.
i will check the back of the HVAC for something there, but i am thinking it might be the switch as the compressor seems to cycle on and off quit a bit, and fast too, only runs for like 20-30 sec, then cycles off for about the same time, before it cycles on again.

 

It sounds as if MikeyB hit the nail on the head with the pressure switch. With the R134-A charge of 1.36 you were about 25% low on a freon. Did the pressures change when the A/C was recharged?

L8r,...........dogger

 

My '05 is going into the shop this week because my AC doesnt work at all and its under warranty. When I pick up the truck what is the correct temp at the vents to check on the test drive? What RPM, Speed should the temp test be made at? I have a hand shaker so I want to get the parameters as close as possible to make sure I dont get air that is too warm coming out of the vents. If anyone knows the temp specs vs. outside air temp I would greatly appreciate it.

Joe

 

Jumper over the High/Low temp sensor with the gauges on to ensure you do not have a blockage(if you have a blockage your high side pressure will spike). See how it runs. Let it run for about 15 min. Everything works O.K. Replace sensor.

 

Mine has a problem also, think its low on freon runs good for quite awhile then slowly it want blow think its freezing up. Push the AC button and let the fan just blow and then it will start getting cold again. What causes the passenger side to be 20 degrees warmer than Drivers side anyone know?