No, I've ruled that out. It actually drops to 25 psi under revs, trips the switch.
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A/C Experts Needed
- Thread starter ikeG
- Start date
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Ok but whats it get to on the low side?
What is the vent outlet temp at the 25 psi? Wonder if the rear evaporator is internally plugged? Have you checked the low pressure ac line temperature as it exits the evaporator?
Is the rear Evaporator clean? Seen them stopped up not allowing for full heat transfer. Don't remember the full symptom list.
Is the rear Evaporator clean? Seen them stopped up not allowing for full heat transfer. Don't remember the full symptom list.
Front vents will be in the 40's. I have yet to monitor rear vents temps
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Some auxiliary info for you to consider
I found two tsb’s stating there has been two different ecm update cal’s for your issue but they dont specifically state for the low side cut off
Is the ecm on the latest cal?
16-na-385 and
19-na-179
Your pressures seem low overall though. With a cooling fan thats weak/not working you should see much higher pressures. Im almost wondering if the pressure side of the compressor is weak. Specially since you overcharged it.
If it cant pressure up the high side enough but still moving volume, its going to pull the low side down too far and trip the switch
Is the ecm on the latest cal?
16-na-385 and
19-na-179
Your pressures seem low overall though. With a cooling fan thats weak/not working you should see much higher pressures. Im almost wondering if the pressure side of the compressor is weak. Specially since you overcharged it.
If it cant pressure up the high side enough but still moving volume, its going to pull the low side down too far and trip the switch
While not moving, the pressures are too high. But I have to simulate driving with a barn fan and scan tool rpm control or just drive it, to monitor it
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How easy can you get to the expansion valve? Can you access it enough to hit the bulb with raw co2 or nitrogen to see if pressure drops out? Or a little heat to see if pressure goes up? You will need to bypass that low side if you cool it.
I have my doubts about a weak compressor. If they struggle to make pressure, they will also struggle to pull down the low side too. Weak compressors typically result in the high and low side pressure being closer together. Doesn't look like that is the case here
As James said, I'd investigate the TXV bulb. Make sure it's working and also properly attached and insulated from ambient air
Does this rear evaporator have a solenoid valve to turn it on and off? Is it working ok and not clogged? No bad electrical connections?
Does this rear evaporator have a solenoid valve to turn it on and off? Is it working ok and not clogged? No bad electrical connections?
Oh ive seen some weird shit but after his last post, it rules that out
Crazy thing, yesterday my HVAC guy was here. Has the same van but the cargo model(front a/c only). Mentioned this issue to him and he says mine is the same way since next to new(bought it used). So we jump in it while i watch data and sure enough, it does the exact same thing under throttle.
The owner of the express van may have lucked into the possible fix for his low side pressure falling too low. The water drain clogged at the cowl, so he had to disassemble the cowl and under hood portion of the heater box to access the drain. While doing so, noticed the evaporator was clogged with debris, only around a 4" circle of fins were exposed. He said it's been doing fine ever since he cleaned and reassembled.
Sad part is his interior was fully flooded because of the clogged drain.
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Sad part is his interior was fully flooded because of the clogged drain.
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