2017 Savana Not cold at idle

[zigblazer]

I just purchased a 2017 GMC Savana for my wife to use as her dog training vehicle. A/C is very important to her, especially at an idle, such as sitting in a parking lot with the dogs in the van. She has a temp warning device that connects to her phone in case of a failure, but we haven't gotten far enough to use it. We live in Northern MN, and don't deal with many days over 90 degrees. However, as yesterday showed, 85 degrees is hot enough to cook the inside of the vehicle. With the van running and A/C on high, the interior was over 90 degrees. The air coming out was cooler than outside, but not cold. Once moving it cools right down. It has the 2.8l diesel engine, so dealing with lower rpms than usual gas engines. I could not find the correct high side port. The only port that fit the high side connector, is obviously reading low side pressures. At idle, with the compressor running, the low side pressure sits right around 50-55 psi, with the electric variable speed cooling fan varying speed (I assume depending on high side pressure) I did not attempt to check pressures with a scan tool, because I've seen very few vehicles that can be read through the ecm and didn't think to check that until now. Revving the engine lowered the pressures a little, but did not appear to result in cooler inside temps. I tried turning the rear a/c off and lowering the front, but the pressures and temps did not change. Driving down the highway, the a/c works great, even with poor airflow through to the rear ceiling front discharge ports.

I believe I will replace the compressor, dryer, and expansion valve/orifice tube. I see the normal service tube for 105- degrees and severe service tube for 105+ degrees, both variable orifice tubes. Is there any benefit to getting the severe service tube, even up here where we only get above 100 once every couple years? Is there any other options for compressors that may work better at lower rpm? Is there anything I can do to ensure cold air at an idle.

Here are the part numbers I have picked to order;

GM GENUINE 1522388 compressor
GM GENUINE 155679 rear expansion valve
ACDELCO 1550122 Severe orifice tube
GM GENUINE 1510345 Dryer

[tbirdtbird]

If you are using a proper manifold gauge set to get your low side readings , ie, a set that reads both hi and lo, and not the kind of single plastic gauge that come with the AC recharge kits from the auto parts store, then my advice is have a shop with an RRR machine recover evacuate and weigh in the correct charge, because it would seem you are low on refrigerant. I would do this before replacing a lot of parts.
How many miles on this vehicle?
Can you provide pix of what you think is the hi side port?
Please note it will be difficult to get the cooling you want at idle…..AC comps do very little if any work at idle speed. Especially an extended idle.

[Carguychris85]

GM dual evaporator a/c systems are actually the vehicles I am probably the best at getting ice cold.

Front orifice tube size has always been wrong, especially on models with rear a/c. You will get better results with a Ford Red 0.062" tube up front. A dirty cooling stack, a rear expansion valve that is stuck fully open, failing compressor or mixture of all 3 will result in high low side pressures. What does the cooling stack look like? It needs to be clean all the way through. The evaporator cores also need to be clean. The front evaporator core is very easy to access from underhood by pulling off the blower case. The vans have never had a cabin filter thud the evaporator core becomes the filter and will need regular cleaning especially in a dog environment. The K9 units were some of the dirtiest a/c evaporators I have seen and that was on Tahoes and Suburbans that were practically new.

Typically the Express will have a transmission cooler dead center of the opening ahead of the condenser that is 11" wide. You should be able to get a pair of 11" pusher condenser fans listed for a 1999 Tahoe 5.7L application in front of the condenser. 1 on each side of the transmission cooler. Wire to a suitable relay with a fused power source, Painless 30101 is a great off the shelf fan wiring kit. Use the Orange high blower relay turn on signal wire at the front blower resistor as a signal to turn on the condenser fans. I would install a 4 port manual heater bypass valve. The heater hoses should come together above the passenger frame rail in the engine compartment allow the installation of said valve. Most of the newer GM vehicles rely on the heater circuit as a coolant bypass for the engine. The 4 port manual shutoff valve maintains the bypass but isolates the heater cores. Other than that look into a high idle setup. The GM diesel should already have provisions in the tune for it. The van may even be able to do it from the factory steering wheel control menus. The changes above should make a huge difference especially with a correctly serviced system.

[Carguychris85]

Dual condenser fan setup on a GM truck. Van condenser is even wider.

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[tbirdtbird]

Sounds like excellent advice, Chris

[Carguychris85]

One other change I made. The rear of my evaporator had 3 layers of aluminum like window screen on the backside. I had a pinhole in the core and had to replace it when my 97 van was about the same age as your van. I moved one of those mesh screen pieces to the front of the evaporator core as a pre-filter. It has kept the actual evaporator core clean and the mesh is easy to clean through the blower motor hole. I use a leaf blower vacuum attachement and it easily pulls all the material blocking flow off the screen.

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[Carguychris85]

Here was the actual core. Absolute failure in GM design not having a cabin filter to keep all this junk out and 20+ years later they still build them the exact same way. The air intake is the cowl under the wiper arms. If you park within the shadow of a tree, cover the cowl vents with a beach towel or tarp and weight it down so it does not blow away. Drastically cuts down on this buildup especially if the van is not driven daily. This sat in my parents driveway for the first 15 years of its life, next to a 115ft tall sycamore tree in the back yard. That tree was responsible for 95% of this buildup.

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[zigblazer]

Thank you. Do you have part number for the Ford orifice tube? Would that single size work better than the severe (hot weather) variable tube?

Other than that, the van is very clean, inside and out. I flushed the cooling system and replaced the thermostat, and while I had the fan out, I removed the grill and pressure washed the radiator/condenser. It wasn't plugged at all, just had a slight buildup of dust around all of the bugs. Yesterday was the first time it has had dogs in it that I know of. We purchased it from a large family, that used it as the regular family vehicle since near new. They usually parked it in the garage or outside their front door, with no trees around. We will be parking it inside the garage anytime it is not being used. I will certainly check/clean the evaps, as that is still seems like a likely reason the rear airflow is low despite the fan going strong, but the front has good airflow and is good and cold while driving.

Thank you again.

[zigblazer]

I will need to look harder for the high side fitting. Hopefully there is one hiding, maybe down near the compressor. I used a cheaper gauge set, that has been working for me for more than 5 years. My r-134a tank has less than 10lbs of refrigerant left in it, but should be enough to recharge the van. I can't verify the high pressures yet (haven't found the port yet), but the fan definitely appears to be varying due to the a/c pressures. Airflow can be felt pulling in even in front of the grill when it is engaged. It is an engine driven fan with a variable electronic clutch. If I get everything replaced and find the high pressures climbing too high at idle, I will likely add an electric fan in front of the condenser.

I also am looking into adding a high idle switch. I have added it to three of my other diesel trucks, and it works great, but I believe they changed to a pto control module in 2011 instead of running it directly from the ecm. I haven't found any information on it yet for the baby diesel in the van. The dealers around here don't have any clue how to work on the diesels past an oil change and replacing parts. They certainly haven't the first clue on upfitter options.

[zigblazer]

Hard to find ones that specify size.
These were the best match I could find, one variable and one fixed.

ACDELCO 1550120 GM red variable orifice tube

MOTORCRAFT YG346 Ford Red Fixed 0.062" tube

What would be my best choice?