Need some assistance with ongoing HVAC issues

[UMDSmith]

Truck: 2006 Z71
I bought this truck 2 years ago with about 98000 miles on it. I have about 110k on it now. Shortly after purchase (bought in winter) the AC was working, but that summer, I experienced times when it would flash the AC symbol and cut out. Did a lot of diagnostics, and the cause seemed to be the temperature gauge for the HVAC system. Replacing the gauge fixed the issue for quite a while. Now I am once again getting intermittent function.

Symptoms: Randomly, the AC won't work. AC symbol flashes. Sometimes after a few minutes, it will cut on. Other times it works perfectly, right when I get in the truck. Temperature doesn't seem to matter, and I'd like to say that humidity isn't a factor, although I certainly notice when it isn't working when it is hot and humid as hell. Compressor will not engage when AC symbol does the flashing.

Cleaned the sensor, no change.

Pressure readings when compressor is running:

• Ambient air temp of about 90
• High side reading of 200-220
• Low side reading of 50-60

Ideas on what to check now?

 

[UMDSmith]

Bump. Any HVAC guys in here?

 

[HiHoeSilver]

Start at the beginning. Have you inspected the belt, tensioner, and clutch assembly? Them clutches like to fail.

 

[UMDSmith]

Start at the beginning. Have you inspected the belt, tensioner, and clutch assembly? Them clutches like to fail.

Yes, belt is new, tensioner is also new. Clutch works. It isn't mechanical, as far as simple things go. The AC works more often than not.

 

[UMDSmith]

I guess the next steps are to drain, flush, and refill the system. I can replace the orifice tube while I'm at it. I don't think that is causing the issue, but at this point I have no idea.

 

[SRQYukon]

Sound like the expansion valve/orifice tube. The AC expansion valve and orifice tube work together to regulate the flow of the refrigerant. If either component fails or has an issue, it can cause it to underperform. The AC system may begin to blow noticeably less cold than before and may even begin to blow warm air

 

[UMDSmith]

Sound like the expansion valve/orifice tube. The AC expansion valve and orifice tube work together to regulate the flow of the refrigerant. If either component fails or has an issue, it can cause it to underperform. The AC system may begin to blow noticeably less cold than before and may even begin to blow warm air

I haven't experienced that yet. When the AC turns on, it does blow cold. It just seems to sometimes not want to engage the compressor and the AC indicator flashes the snowflake. It does eventually turn on, but I do plan on swapping out the orifice tube.

 

[Doubeleive]

I had similar issue's on my 03 with the digital controls, replaced the control unit,-problem solved they do go goofy, just my 02 cents
before it was replaced it would work "sometimes" right off the bat, other times it would blow warm air and you would have to turn it off, turn it back on sometimes once sometimes a few times, or you would have to shut the engine off, restart and try again. other times it would be working fine, then after sitting at idle it would blow warm air again, then blow cold upon acceleration just like there was a compressor/system issue, but it wasn't. after replacing the control unit works perfect again blows ice cold.

mine did not however flash the snowflake as you are reporting

 

[Rocket Man]

Does it start working again if you drive awhile and get air flowing across the condenser? Might check the condenser for leaves and other types of blockage as well as electric fan operation ie make sure the fan comes on when the compressor cycles on.

 

[SRQYukon]

I'm guessing this is a long shot, some vehicles (not sure about yours) have a compressor speed sensor that shuts down the A/C if the pulley is turning too slowly and monitors the speed to auto-adjust the blower speed. Possibly, if the '06 has one, it could be bad. I know we have one my wife's Lexus. Anytime the belt gets wet driving through puddles, the A/C shuts off. My son-in-law services auto A/Cs and he says the sensors give him fits sometimes because the symptoms sometimes aren't exhibiting themselves when to car comes in for service. Not sure if your symptoms represent what would happen if it's bad, though. It would be nice if you could post the outcome when you sort out the problem Maybe we can all learn something.