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Discussion Starter · #1 ·
So read through several post and here where i'm at. Hvac systen on my 2004 Mada was checked and refilled about 3 weeks ago. I've driving the car around 5 times since then. The AC will take a while for the cabin to cool down like 10-15 minutes. I'll run for around 20 minutes cooling the cabin. Then you can feel the cabin warming up, then eventually cool down again, repeating.

So rented the AC manifold gauge set from Autozone. The reading where taken at 82 degrees with 52% humidty.

Base reading with car off and cold (hadn't turned on since Friday)
Low: 75
High: 75

With truck idling and Front & Rear AC running
Low: 25
High:100
Cabin fan speed : 3/4
Vent temp: 80

With truck idling and Front AC only running
Low: 10
High:100
Cabin fan speed : 3/4
Vent temp: 80

With truck around 1500 rpm and Front & Rear AC running
Low: 0
High:100
Cabin fan speed : 3/4
Vent temp: 80

Took the truck for a 20 minute drive and the vent temp drop to 70. Below are the measurements after driving the truck

With truck idling and Front & Rear AC running
Low: 15
High:125
Cabin fan speed : 3/4
Vent temp: 80

With truck around 1500 rpm and Front & Rear AC running
Low: 0
High:125
Cabin fan speed : 3/4
Vent temp: 80

With truck turned off
Low: 75
High:100

So turning to this community hoping someone can translate this measurements on what action i need to take next,

Thanks in advance,

Nick
 

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if you had it "checked and refilled " 3 weeks ago and its not performing as expected, you clearly have a leak. fix that first and stop dispensing refrigerant into the atmosphere.
 

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Discussion Starter · #3 ·
if you had it "checked and refilled " 3 weeks ago and its not performing as expected, you clearly have a leak. fix that first and stop dispensing refrigerant into the atmosphere.
So based on my measurement posted above it clear i have a leak? So bad compressor, condensor is out of the question?
 

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if you had to recharge the refrigerant then for sure you had a leak. my point in all of this is there should be a logical step to diagnosing this. first thing is to verify you don't have a huge leak.

if temps are cooler when the car is at speed (high rpm) this might suggest low refrigerant. if the high side is really high you may have blockage in the system.
 

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You are definitely leaking refrigerant. At normal operations idle or any RPM with compressor running: LOW: 30-35 psi, HIGH: 300-350 psi. Look for signs of oil stains on any/all of your A/C lines. It's a sure tale sign that there is a leak. Most refrigerant leaks occur at a connection or fitting.
 

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Discussion Starter · #6 ·
Got the Mada back from my mechanic yesterday. He check the AC system and he said its working, when it works. had it running for an hour and it was blowing cold air. He thinks my issue is with the fuse box, since the compressor works an generates cold air. When i picked it up, it work for like 5 minutes got the vent down to 60 degrees, outside temp was in the 90.

The backstory is my AC on occasion on long trips (over 4 hrs) would cut off. Turning the AC system off & on , would be sufficient for the AC to start cooling again. In October 2019 we did a 800 mile trip, on the way home the AC starting acting up and turning the AC system off & on would not resolve the issue immediately. Took it to my mechanic, he hooked it up to the machine and flushed out the AC system. AC system didn't get used till 2020 sprint time. Many trips to the mountains to ride the quads during that period. Did have to turn the AC system on ahead of time. So by the time we loaded up the trailer and strap everything down, the AC would be cooling the cabin down.

Around this time last year on a trip to the mountains, the Mada shutdown and the AC stop working. Had enough momentum to make it to a turn off. Got the dreaded efficiency code pertaining to the cats. The Mada didn't get much used after that, till i got the cats replaced in January of 2021. While prepping for a trip with the Mada earlier this year. Though i found the AC issue, a pop fused, replaced the fused and AC worked. I've had the AC fused pop a couple times since then. Prior to the 4th July weekend i checked to make sure the AC system working. It 's working sporadic, i checked the intake sensor and it checked out fine.

My next step is to wire the compressor directly with a fuse in line. Just to confirm that its will blow cold hair for as long as i have it connect that why and take some reading of the high & low pressure lines. The only other thing i can think of is the FAC is bad since the inlet sensor checked out per FSM.

Thoughts anyone?
 

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i would not bypass the sensors in the system so that the compressor is always on and not getting any input from the ECM. you are asking for trouble. this car has sensors and programming that tell the compressor when to work and when not to. the high and low sides need to work together based on certain RPM and engine speed to keep the system in equilibrium.

no disrespect, but it sounds like your mechanic does not fully understand the system. you have a leak , this is evident to me. the fact that the mechanic did not suggest this or find the source of the leak(s) tells me you should find someone else or take it to nissan and have them diag the issue.

you may have an issue with the sunload sensor in the car, or any of the other sensors in the hvac system. loose /frayed wiring and /or an "intermittent" relay can be your issue. it takes time to diagnose it. "flushing out the ac system" -- what is that? it's not a radiator and water pump.

at the end of the day its your car and you can do with it what you will.
 

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Discussion Starter · #8 ·
no disrespect, but it sounds like your mechanic does not fully understand the system. you have a leak , this is evident to me. the fact that the mechanic did not suggest this or find the source of the leak(s) tells me you should find someone else or take it to nissan and have them diag the issue.
That's the impression i got from him. He didn't want to tackle the AC issue because of the sensors involved. Compared to my ford truck that he worked on. The AC system had no sensors involved and my AC is blowing ice cold in the low setting. Want to avoid the dealer if possible and there hourly charge that will add up real quick.

you may have an issue with the sunload sensor in the car, or any of the other sensors in the hvac system. loose /frayed wiring and /or an "intermittent" relay can be your issue. it takes time to diagnose it.
I checked the sunload/intake sensor with a volt meter and it was in range per the FSM chart. let it sit in the sun and resistance went down, placed it in the fridge and resistance went up. I was hopping it was the case. Yeah i'm starting to think i have separate issues one is the fuse blowing and the other is lack of AC.

"flushing out the ac system" -- what is that? it's not a radiator and water pump.
It's when you hookup the machine with the hoses and circulate the Freon through out the system.

You are definitely leaking refrigerant. At normal operations idle or any RPM with compressor running: LOW: 30-35 psi, HIGH: 300-350 psi. Look for signs of oil stains on any/all of your A/C lines. It's a sure tale sign that there is a leak. Most refrigerant leaks occur at a connection or fitting.
Only issue is i pressured wash the engine compartment not to long ago.
 

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thanks for the feedback. I actually have a license in R134a and R12 installation and capture but that is not something I talk about on here. I know the steps involved with respect to evacuating and recovering refrigerant. It's not usually called "flushing out the ac system".

I understand you don't want to hit the dealer, but you should at least find someone who has knowledge in newer model AC systems that know their way around sensors and the computer (CANBUS) side of it. it seems you know more than the actual mechanic!

pressure washing the engine should be done with care as there are sensitive sensors and components that will have adverse effects to water. older engine components may have water egress and if this gets into a wire harness, that's an issue. I washed my engines (2006 and 2008 armada and 2012 qx) but I did not use high pressure water because of sensors and sensitive components in the engine room.
 

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You can also try using a water and soap solution mixed in a spray bottle. Spray around A/C fittings, valves, hoses, connections and condenser fins.
 
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Discussion Starter · #11 ·
I think i found my leak. From what I gather from reading the forums, I need to replace the condenser unit. Can someone point me in the right direction for a good write up on this, much appreciated.


50515
50516
 

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I think i found my leak. From what I gather from reading the forums, I need to replace the condenser unit. Can someone point me in the right direction for a good write up on this, much appreciated.


View attachment 50515 View attachment 50516
Attached is the Factory Service Manual for your year model. Unfortunately it not as explicit. Also I attached the write-up from my Haynes repair manual. Hope both will be helpful

Sorry I could not upload the FSM the file was too large. But you are not missing anything from the FSM. It was vary Vague.
 

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Discussion Starter · #13 ·
Attached is the Factory Service Manual for your year model. Unfortunately it not as explicit. Also I attached the write-up from my Haynes repair manual. Hope both will be helpful

Sorry I could not upload the FSM the file was too large. But you are not missing anything from the FSM. It was vary Vague.
Thanks, I have the FSM. Just looking for tips & tricks. I've replaced the radiator and fan clutch so now my way around the area. I've also watched a couple YouTube videos. Going to replace my water pump & thermostat while I'm there since I'm close to 200K miles.

Good Morning,

Got everything taken apart, have some small parts arriving this morning from Nissan. Have a question on how much oil to add to the system. One person who replaced his condenser added 70ml. Service manual says to add oil but no mention of how much. The only reference i can find, on how much oil to add is when replacing the compressor. So should i use that number 6oz or the 2oz (70ml)? Since my condneser had a leak did all the oil leak out?

Thanks,
 

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Good Morning,

Got everything taken apart, have some small parts arriving this morning from Nissan. Have a question on how much oil to add to the system. One person who replaced his condenser added 70ml. Service manual says to add oil but no mention of how much. The only reference i can find, on how much oil to add is when replacing the compressor. So should i use that number 6oz or the 2oz (70ml)? Since my condneser had a leak did all the oil leak out?

Thanks,
No, not all the oil has come out. Make sure you evacuate your A/C system before attempting to recharge. 2oz is a good starting number and as much as 4oz
 

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Discussion Starter · #15 ·
Got it all put back together. Took it in to get the AC system evacuated and refilled. Took about 15 minutes to see the vent temp change. As soon as the clutch would disengage the vent temp would rise. This was around 7pm, temp at 79 degrees 56% humidity, vent temp 70, low pressure line 55, high pressure line 100. Took it for a drive and got the vent temp down to 40 degrees.

Drove it today on a short trip, 45 min. Vent temp would not get lower than 60 degrees. It keep cycling on & off , vent temp would rise to 70 degrees then lower to 60 degrees. On the way back the vent temp was mostly at 60 degrees and on several occasions drop to 50 degrees. I read somewhere on the forum the cycling on & off was resolved by replacing the condenser sensor. Is there a way to test the sensor? Will i have to refill the system?
 

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There are lots of environmental, system pressure and temp at play. The temperature reading you are getting looks normal for the current ambient temperature and cabin temperature. Now, you could have a bad pressure sensor, but, I'd evaluate the current (fixed) condition further, with more drives and different outside temperatures. TBH those temperature you are getting now are really good. I consider that a snow machine...lol but that is just me. I like my cabin temperature at 78 degrees. Anything lower I'll be wearing a winter jacket.
 

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Discussion Starter · #17 ·
There are lots of environmental, system pressure and temp at play. The temperature reading you are getting looks normal for the current ambient temperature and cabin temperature. Now, you could have a bad pressure sensor, but, I'd evaluate the current (fixed) condition further, with more drives and different outside temperatures. TBH those temperature you are getting now are really good. I consider that a snow machine...lol but that is just me. I like my cabin temperature at 78 degrees. Anything lower I'll be wearing a winter jacket.
I'll drive some more and see if anything changes. The issue is you can feel it in the cabin as soon as the AC cycles off.
 

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I'll drive some more and see if anything changes. The issue is you can feel it in the cabin as soon as the AC cycles off.
After several drives and you still not satisficed. Next You'll need to hook-up gauges and simulate a typical driving condition. This time around you will be checking the system's operating pressures. I hope you have A/C pressure gauges. I think you can rent one at AutoZone? Are you capable of doing this? If so I'll send you directions of what to do. Otherwise have a capable shop do it. But a Nissan dealer will be best ONLY because they know the INs and OUTs of the SUV system's HVAC control circuits. at least they should know??? NOT always the case.

(Objective - is to place the A/C system in max load.)

1. Hook up gauges to you A/C system. A normal static pressure (A/C not running) is about 100 psi on both LOW (Blue) and HIGH (Red) gauges.

2. Open all windows, Engine running @1500rpm or higher(simulating a driving condition), Turn ON your A/C and place your A/C temp setting to its lowest possible setting and run blower on HIGH. You might need an assistant to keep the engine revved up. Make sure all you fans are running in the engine compartment and engine temp is normal too. At this point you don’t care too much about cabin temps.

3. If your system is running normal. System pressures should read: LOW (Blue) gauge between 55 psi (expansion valve fully open) to 70 (Closed). Any pressure in between is considered good. HIGH (Red) gauge between 300 to 350 psi. Important to watch the HIGH gauge. Abnormal pressure above 350 psi, will cut-off (cycle the compressor ON/OFF). A high pressure situation would indicate not enough air flow going thru the condenser or other things. To include a bad high pressure sensor. Or cutting out too soon
PSI below 300 PSI. which hardly happens.

There are other conditions that will cause a compressor to short cycle (constant ON/OFF) condition. But it’s hard to evaluate that on the internet. Unless maybe posting a video of gauges during your test. A good run is about 10 to 15 minutes. But the above should give you a starting point to further troubleshoot.
 
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Discussion Starter · #19 ·
System seems to be working fine now. 90 degrees 30% humidity. Vent temp 60 degrees at idle, AC system kick in quickly and started cooling the cabin. Let it idle for 20 min and vent temp held at 60 degrees. Took it for a drive and vent temp range from 45 degrees - 55 degrees. Will drive it a couple more times during the week and will monitor vent temps.
 
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