azjaybird

Hey guys, first time on here, but I figured this would be a great place with some smart people so here it goes....

I live in Arizona and have several Chevy Express 3500 12 and 15 passenger vans. Recently this summer I've been having issues left and right with these vans and getting the AC to blow cold. I've taken them to a few shops and seem to be getting the run around, pretty much everyone tells me everything is working as it should, it's just the heat outside and it's a big van and a lot of area to cool down, etc. Granted it's been 110 degrees or so for about the last month or more, so I'm not sure if my expectations are too high?

I will say when I'm driving them, the ac seems to be pretty cool/cold, the best I've been about to get them when driving is about 58 degrees, but that usually only happens when its under 100 degrees outside. Sitting still is where they really kill me, I haven't been able to get them to blow any colder than about 78 or so when sitting still, which I think is pretty unacceptable, or at least to my customers. I rent them out and I have people bringing them back telling me the air isn't cold enough. They do seem to be exponentially better when I drive them in the morning and the outside temp is in the mid 90's or so. Are these AC systems that more efficient at say 96 degrees versus 110?

I'm hoping to get some insight as to what I can expect the lowest temp I can get these vans to be? Given that it's 110-115 some days, is it pretty much impossible to get these vans to blow say 60 sitting still and 50 or lower going down the road? I've been told by a couple shops that it's just too hot outside and that's just the way it is more or less. I'm not sure if it's a fair comparison, but I have several other vehicles (Wrangler, Toyota FJ Cruiser, Lexus GX, Chrysler 200) that blow ice cubes out of the vents sitting still. I had my Jeep at about 45 degrees the other day. I'd like to think the vans should be a lot better than I'm currently getting.

Are there any tricks or things I should be looking at that maybe I'm overlooking? Any parts that are known to fail or give issues, etc? Given that I'm charging these AC systems in 110 degree heat, should I be putting less r134 in them to compensate? What should I be shooting for as far as a high side and low side pressure? Does the condenser play a big role in making the AC blow ice cold? Everytime I mention the condenser to the shops, they say "oh the condensers rarely ever go bad" or "we don't see any blockages in the condenser" etc.

Side question..... is it possible to charge these AC systems using the small 12oz cans or is that a big no-no? I have the manifold gauges and have evacuated the system several times and recharged them with the required amount of freon, but I've also been told that using the small 12 oz cans are almost impossible to charge an AC system properly. I've also taken the vans to shops and had them evac and recharge the AC with their big $10k AC machine and seems to yield the same results. If its any consolation, I've used the manifold gauges and 12oz cans on several other vehicles and have never had an issue.

I'm losing a ton of business because I can't seem to get these things dialed in and blowing ice cold.

Any help would be GREATLY appreciated, I've all but given up hope at this point. Have a great day everyone!

Triaged

Might want to look into if the fan clutch is working properly. Only trust OEM fan clutch if you replace it.

Derrick71

The symptoms sound like the radiator fan clutch going out. The fan clutch can go out in a way that it can pull enough air to keep the van from overheating but not pull enough air to cool the condenser. When you're moving there's plenty of air flow and it cools off. Similar to when an electric cooling fan goes out but more subtle since the fan is still moving some air.


When it happened to mine I had the same symptoms. I'm in Florida where it's also pretty hot. I put a thermometer in the vent and was getting into the high 40's going down the highway. At idle it would creep up to the low 70s and be pretty warm inside. High side pressure would also rise. Coolant temp gauge never changed. I often eat lunch in the van with the AC running so it was becoming an issue. It was only an issue when it was really hot and sunny so it could be that all of your vans have had the issue for a while but it's just now showing up in the intense heat.

The clutch is supposed to loosen up when cooler air blows over it and stiffen with heat for more fan engagement. The clutch can be hard to diagnose since it might feel stiff just spinning it by hand but loosen up at speed. It has a temp controlled valve that lets fluid move through it to create this effect. It can fail by free wheeling the whole time, locking up the whole time (both easy to diagnose) or somewhere in between where it seems fine but pulls less air. The fluid moves through it with centrifugal force so spinning it by hand doesn't always tell you anything. A properly working clutch be fully engaged when first starting it from fully cold (about 30 seconds) since the fluid pools and collects in one spot so don't worry about what it does when fully cold.

As a test I let the van idle in the sun with the AC on and fully heat soak till the vent temp reached the 70s and held there. I then put a strong box fan and a small leaf blower in front of the grill to increase air flow and it dropped the vent temp by about 10 degrees after a few minutes. I removed the fan and blower and it crept back into the 70s. I wasn't able to create the same airflow as a working radiator fan so any noticeable change confirmed it was an airflow issue. The radiator fan moves a lot of air and has the shroud to focus it so just a small fan might not work for this test.