AC issues

[Dozerboy]

Another guy with AC question on my 2006 duramax. So my AC was only getting down to 60* at the vents and took an hour driver to really cool off. Normally its 40*s at the vents. I rented some gauges and bought 3 12oz cans of pure 134. Before adding any the low side was 35 and the high was 180. After the first can 40 and 220 the second can got it to 45 and 250, but it stopped climbing1/2 way through the can it seemed. I added a 3rd can and tried another set of gauges, but probably lost 1/2 of it due to a leaking hose. The pressures didn't change any. Per the charts for 134 I should be seeing 50-55 and 250-275 @ 90*-95*. I'm worried I over the system, but why are the pressure not any higher? The temperature of the AC is 40* at the vents. The AC is untouched since 2006 other them this is the 2nd time I've had to add 134. I don't recall the pressures last time, but they where a little on the high side at 90* to get it to cool to 40*.

Suggestions??

 

[Chevy1925]

You probably overcharged it, careful with that as it’s a good way to kill the compressor.

Is the a/c set with recirc on, blower at max, and full cold? Rpm at 2k? Then taking pressure readings?

 

[2004LB7]

Plus windows or doors open

 

[DAVe3283]

The GMT800 has a massive accumulator, so going a can past full probably won't be enough to draw liquid into the compressor. Plus it sounds like it will leak back down soon enough anyway

The high side not being as high as you'd expect could just be the system not being under full load. As was mentioned, you need to have the AC on full cold, fan at max. I personally don't put it on recirculate, as I want to hit the evaporator with the hottest air possible to load the system. But do at least have the windows open either way.

That said, since you don't have gauges and it's blowing 40°F out the vents, I'd leave it where it is. What you showed seems safe enough, besides maybe being a bit overcharged.

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[jlawles2]

Have you checked the cooling fan on the engine for engagement? Also with the recent heat wave in the south, AC systems are struggling. I suggest you check the stack just to be certain something did not get in there and plug up the air flow.

One other thing to check is temperature differential on the passenger side of the system just before the small line enters the cab. This should be the throttling point where liquid flashes to gas. There should be a MAJOR temp difference across this point. Not common but throttling points do go bad (normally they become restrictions forcing the low side pressure down and high side pressure UP.

I know it does not have a cabin air filter, but you may need to flush the evaporator core (dust tends to build in them). I ran a can of this through the GF's car to get rid of a bad BO smell and the crud that came out was amazing (even though car had a cabin air filter). https://www.amazon.com/gp/product/B0002Z2MKO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[Dozerboy]

You probably overcharged it, careful with that as it’s a good way to kill the compressor.

Is the a/c set with recirc on, blower at max, and full cold? Rpm at 2k? Then taking pressure readings?

Yes other then 2k RPMs. I didn't have anyone to help me. I did check them at 2k RPMs yesterday, but I don't remember the readings now. I know they weren't much higher. For sure not what they should of been per the chart.

Is there a wrong what to drain some out of the system? Vehicle on/off, ac on/off, high side/low side?

 

[Dozerboy]

Have you checked the cooling fan on the engine for engagement? Also with the recent heat wave in the south, AC systems are struggling. I suggest you check the stack just to be certain something did not get in there and plug up the air flow.

One other thing to check is temperature differential on the passenger side of the system just before the small line enters the cab. This should be the throttling point where liquid flashes to gas. There should be a MAJOR temp difference across this point. Not common but throttling points do go bad (normally they become restrictions forcing the low side pressure down and high side pressure UP.

I know it does not have a cabin air filter, but you may need to flush the evaporator core (dust tends to build in them). I ran a can of this through the GF's car to get rid of a bad BO smell and the crud that came out was amazing (even though car had a cabin air filter). https://www.amazon.com/gp/product/B0002Z2MKO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I do need to check the fan and the cabin filter/evaporator. The stack is good. It got tore apart and cleaned less then 5k miles ago when I did HGs.

Definitely toasty here. What sucks is the AC in my LBZ weekend truck works way better then my 2020 F250 work truck. That thing is on full blast by noon and the vent Temps are only 50*s.

 

[Dozerboy]

That said, since you don't have gauges and it's blowing 40°F out the vents, I'd leave it where it is. What you showed seems safe enough, besides maybe being a bit overcharged.

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I have gauges they are just rental from Auto zone and were questionable to me.

 

[Dozerboy]

I did also check the pressures on my 2020 f250 that got a new compressor a few months ago. They where just a little lower at 42 and 235. Again ac on full blast windows open but only idle. Not that that means much necessarily because AC doesn't cool really good, but it never has.

 

[DAVe3283]

Officially, the _legal_ way to remove some refrigerant is with a recovery machine. Just venting it is not allowed.

That said, you can remove refrigerant from either the high or low side with the system off or operating. The easiest is probably to release some with the truck off. Knowing how much you've removed is going to be difficult without capturing and weighing it.

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[darkness]

Just connect and disconnect your lines a few times and boom, de minimis, totally legal…

 

[wydopenLb7]

Instead of starting a new thread I'll ask here. I've been having some weird ac issues. Hot day, start on a 2hr trip and the ac is ice cold for the first 1.5hrs. Suddenly the amount of air coming out of the vents decreases even though you can hear the fan still blowing. What little air that is coming out feels cold but you have to hold your hand up to the vent to feel it. Lines and condenser are covered in ice if you pop the hood. Next time you start it the ac will work normally again. Blend door actuator issue? I've had one sitting on my desk for awhile. Was making a noise (mainly with the heater if I remember correctly) and then stopped doing it and had been working normally until recently. Thanks for the suggestions.

 

[2004LB7]

Instead of starting a new thread I'll ask here. I've been having some weird ac issues. Hot day, start on a 2hr trip and the ac is ice cold for the first 1.5hrs. Suddenly the amount of air coming out of the vents decreases even though you can hear the fan still blowing. What little air that is coming out feels cold but you have to hold your hand up to the vent to feel it. Lines and condenser are covered in ice if you pop the hood. Next time you start it the ac will work normally again. Blend door actuator issue? I've had one sitting on my desk for awhile. Was making a noise (mainly with the heater if I remember correctly) and then stopped doing it and had been working normally until recently. Thanks for the suggestions.

Low on refrigerant and the evaporator is icing over blocking airflow. When it happens can you turn off the AC but leave the fan on for a few minutes and the air will slowly come back as the ice melts?

 

[wydopenLb7]

Low on refrigerant and the evaporator is icing over blocking airflow. When it happens can you turn off the AC but leave the fan on for a few minutes and the air will slowly come back as the ice melts?

I tried to add some previously but it wouldn't take any more. I will try that if it does it again in the next week, was blowing cold today. I've tried turning it off before but I probably didn't wait long enough before getting annoyed and rolling the windows down. Going to be disconnecting the lines anyways this weekend to do some other work so hopefully when it gets refilled it will solve it. Thank you.