A/C pressure checking / charging ... dumb question (1 Viewer)

[chrisbruck]

For those with the factory rear A/C and everything still stock and working properly, quick pressure checking question...

I have the FSM and it says with the sight glass or the manifold gauges to have "fan speed at hi, AC ON, temp to full cool, doors open".

It makes no mention of the rear AC. Does this need to be on full too? I've noticed I see different results in the sight glass and on the gauges if the rear AC is on or off as well. Trying to determine to proper way to charge and top off the AC as needed. Don't want to overfill it.

Any thoughts or AC expert advice?

 

[Patassa]

For those with the factory rear A/C and everything still stock and working properly, quick pressure checking question...

I have the FSM and it says with the sight glass or the manifold gauges to have "fan speed at hi, AC ON, temp to full cool, doors open".

It makes no mention of the rear AC. Does this need to be on full too? I've noticed I see different results in the sight glass and on the gauges if the rear AC is on or off as well. Trying to determine to proper way to charge and top off the AC as needed. Don't want to overfill it.

Any thoughts or AC expert advice?

Maybe dumb question also but why wouldn't you just get pressure readings on both sides of the system and compare to the manual? If low, add refrigerant. Otherwise, you're good? Only mystery to me was how much oil to add back in after replacing various components, not as easy to nail that one down, have to estimate unless you're really good at getting all the oil out of those components and measuring it.

 

[chrisbruck]

My followup dumb question to your dumb question, haha.

Since only one compressor, isn't the high / low pressure ports in the engine the only ports to access? Does the rear system have separate ports? I see no mention of that in the FSM and don't see any when I looked under the vehicle to the back evaporator either.

 

[nissanh]

My followup dumb question to your dumb question, haha.

Since only one compressor, isn't the high / low pressure ports in the engine the only ports to access? Does the rear system have separate ports? I see no mention of that in the FSM and don't see any when I looked under the vehicle to the back evaporator either.

Have all running as stated. If you have proper amount of gas to cater both front and rear, you will see a bubble or two in the sight glass per second or two, but not continuous bubbling.

 

[blinkerfluid]

do you want to top up or remove the refrigerant and recharge again?

always keep the blower to full, front and rear, all windows open -

 

[chrisbruck]

Just checking and topping up. Overall it works great but a few years back got a little low and froze up on a trip so now I just check each spring and have noticed turning on the rear system causes the bubbles and pressures to vary a lot more.

 

[Patassa]

My followup dumb question to your dumb question, haha.

Since only one compressor, isn't the high / low pressure ports in the engine the only ports to access? Does the rear system have separate ports? I see no mention of that in the FSM and don't see any when I looked under the vehicle to the back evaporator either.

Since it's all one closed loop system, I'm imagine the pressures on both sides of the compressor need to match what's in the manual with or without the rear a/c running, the extra pressure drop going through the rear system should be accounted for by the compressor running longer. That's at least how I'd imagine toyota designed it.

 

[DTCsk8er]

I treated my refilling as if the rear AC didn't exist at all. Rear AC blows cool after a minute or two of blasting the heat out of the vents.