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Discussion Starter #1
Hello all,

I have an issue that is throwing me fo a loop. Hopefully someone has dealt with this before.
Had a/c problems about a year ago. A/c would intermittently work. Pretty bad during daytime operation. Anyways took it to local mechanic. He said the compressor was on its way out. 30 seconds later his helper comes out and says he got it working. Added some refrigerant I guess, he didn’t say. Kinda forgot about it thru the winter but as soon as the Louisiana heat set in, problem was back.
I swapped out compressor, condenser, and expansion valve. Pressure tested with nitrogen, no leaks. Pulled vac for 2 hours. Recharged with 1.16lbs of 134. Started car and within 3 minutes, the interior was nice and cool. Next, morning cranked again and same results. Thought all was good.
Later that afternoon wife heads to store and texts that the a/c is blowing hot again. Two minutes later she calls and says she turned the a/c switch off and back on and it is blowing real cold. When she gets home, I leave the car running and throw the gauges on. Low side 40, high side 195, ambient 94, vent 47.
Turned car off, gauges evened out with 10 seconds or so around 115 psi. Did a visual to check previous days work, all sat.
Cranked car again, hot air. Visual on compressor clutch indicates it is engaged. Pressures remains at 115 on high and low side. Back in car, turned of ac switch, 15 seconds turned on. Noticed high speed on radiator fan kicked on. Low pressure dropped and high pressure increased. 42/200. Cool air in cabin.
Thought about it thru the night and decided maybe the relay was intermittently bad and I would change out. Before doing this I went thru the following:
0910 - engine off, low 105, high 100, ambient 88
0916 - engine started, high sped fan on within 15 sec., low 35, high 180, cab vent 46, ambient 88
0921 - low 38, high 175, rad fans on high
0924 - low 40, high 175, fans on, vent 48
0933 - low 40, high 185, fans on, vent 48, ambient 88
0934 - secure engine, low 105, high 100 within 15 sec. 5psi maybe the harbor freight calibration
0936 - start engine, fans kick on and pressures back to 40/180 range, good cooling inside cab
0942 - turn off ac switch in cab, rad to low speed, compressor clutch disengage, temp in cab gradually increasing
0944 - turn switch back on, all good with pressures, clutch engagement and cooling in cab
0950 - secure engine, noticed a little condensation on low pressure line, Luke warm to the touch
1000 - started engine for road test ( no gauges, obviously)
1003 - 25 mph thru neighborhood, vent temp 41

Drove 12 miles with no problem on city streets and interstate. Ac vent temp averaged 42. Always very comfortable in cab

Stopped in parking lot and secured engine for 10 mins

Started engine, hot air. Turned ac switch off and back on 30 sec delay, all well again.

Went back to the relay idea, 20 bucks later, no fix.

What tells the condenser/radiator fan to kick to high speed? Ac switch?
How can the compressor clutch be engaged and on pressure change on the gauges?

Thanks in advance for the help.
 

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Hi Snipe48

I am having a pretty similar issue. I just bought my altima a couple of weeks ago.


 

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If you are showing same pressures on both low and high and both 100 psi or higher the compressor is doing nothing. Maybe a valve stuck in it of some type?
 

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Discussion Starter #4
amc49,
Thanks for the info. I guess I’m hesitant on going straight to the compressor bc the even pressures tricked me in to condemning the other one. Thought for sure when I first saw the compressor engaged and no pressure change, it was bad. It very could have been and the one I have now maybe junk. Idk

The compressor engaged and the pressures not moving confused the hell considering simply turning the a/c off and then back on seems to get the cooling started.

Been jumping around from IDPM, to different relays that may be tied in.

Going thru the tech manual, seems at least 4 or 5 sensors are verified for the control system to kick the compressor/ high speed fan on. One of which is the pressure switch ( kicking myself for not changing when condenser was out). Other thing that came up was the ecv sensor in the compressor.

I don’t see a real good description of the purpose of the ecv sensor on a clutch driven compressor but the wiring diagram references it. I thought ecv was constant with engine rpm. Do you have specifics?

what are your thoughts on the sensor in the compressor or the pressure switch (or both together) not allowing the compressor to build pressure? Built in relief until sensors read safe?

Maybe in left field here, just reaching.

Thanks again for taking a look
 

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Snipe48

I am having almost the same issues... I have a feeling that it is a sensor.
My AC works fine (actually cools not just fresh air) in the morning, nights and chill days (less than 85 F) but on hot days 90+ it stops working. It blows hot air, but I always see the compressor clutch spinning.

This are the sensors that I am planning to change but I ran out of budget...
  • Pressure switch sensor (the one which is on the dryer)
  • Ambient sensor
  • ECV Sensor
 

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Discussion Starter #6
amc49,
Thanks for the info. I guess I’m hesitant on going straight to the compressor bc the even pressures tricked me in to condemning the other one. Thought for sure when I first saw the compressor engaged and no pressure change, it was bad. It very could have been and the one I have now maybe junk. Idk

The compressor engaged and the pressures not moving confused the hell considering simply turning the a/c off and then back on seems to get the cooling started.

Been jumping around from IDPM, to different relays that may be tied in.

Going thru the tech manual, seems at least 4 or 5 sensors are verified for the control system to kick the compressor/ high speed fan on. One of which is the pressure switch ( kicking myself for not changing when condenser was out). Other thing that came up was the ecv sensor in the compressor.

I don’t see a real good description of the purpose of the ecv sensor on a clutch driven compressor but the wiring diagram references it. I thought ecv was constant with engine rpm. Do you have specifics?

what are your thoughts on the sensor in the compressor or the pressure switch (or both together) not allowing the compressor to build pressure? Built in relief until sensors read safe?

Maybe in left field here, just reaching.

Thanks again for taking a look
 

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Discussion Starter #7
Snipe48

I am having almost the same issues... I have a feeling that it is a sensor.
My AC works fine (actually cools not just fresh air) in the morning, nights and chill days (less than 85 F) but on hot days 90+ it stops working. It blows hot air, but I always see the compressor clutch spinning.

This are the sensors that I am planning to change but I ran out of budget...
  • Pressure switch sensor (the one which is on the dryer)
  • Ambient sensor
  • ECV Sensor
Lagc24
I am still looking into the matter.
Right now, if the a/c is blowing hot the fix is to turn the system completely off and back on.
Works great afterwards. I doubt this will last long so I will keep digging.

Compressor engaging with no cold air. Put the gauges on before you start and pay attention to pressures. Mine is showing around 130 on high and low.
Kick on a/c, see if it stays the same, see if compressor is engaged. If it does (as mine sometimes does) you may want to check the electric control valve operation integrated in the compressor or at least the controlling source
Seems as thought the ecv is a direct connection to the high and low side in certain circumstances

I am going thru the wiring diagrams when I get free time.
If I happen upon a fix, I ill let u know
 

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i think you may be overfilled with 130 static mine is closer to 100psi at 89f but getting an accurate static reading can be tricky, you should not be in the sun and should wait for pressures to equalize.
 

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Hello all,

I have an issue that is throwing me fo a loop. Hopefully someone has dealt with this before.
Had a/c problems about a year ago. A/c would intermittently work. Pretty bad during daytime operation. Anyways took it to local mechanic. He said the compressor was on its way out. 30 seconds later his helper comes out and says he got it working. Added some refrigerant I guess, he didn’t say. Kinda forgot about it thru the winter but as soon as the Louisiana heat set in, problem was back.
I swapped out compressor, condenser, and expansion valve. Pressure tested with nitrogen, no leaks. Pulled vac for 2 hours. Recharged with 1.16lbs of 134. Started car and within 3 minutes, the interior was nice and cool. Next, morning cranked again and same results. Thought all was good.
Later that afternoon wife heads to store and texts that the a/c is blowing hot again. Two minutes later she calls and says she turned the a/c switch off and back on and it is blowing real cold. When she gets home, I leave the car running and throw the gauges on. Low side 40, high side 195, ambient 94, vent 47.
Turned car off, gauges evened out with 10 seconds or so around 115 psi. Did a visual to check previous days work, all sat.
Cranked car again, hot air. Visual on compressor clutch indicates it is engaged. Pressures remains at 115 on high and low side. Back in car, turned of ac switch, 15 seconds turned on. Noticed high speed on radiator fan kicked on. Low pressure dropped and high pressure increased. 42/200. Cool air in cabin.
Thought about it thru the night and decided maybe the relay was intermittently bad and I would change out. Before doing this I went thru the following:
0910 - engine off, low 105, high 100, ambient 88
0916 - engine started, high sped fan on within 15 sec., low 35, high 180, cab vent 46, ambient 88
0921 - low 38, high 175, rad fans on high
0924 - low 40, high 175, fans on, vent 48
0933 - low 40, high 185, fans on, vent 48, ambient 88
0934 - secure engine, low 105, high 100 within 15 sec. 5psi maybe the harbor freight calibration
0936 - start engine, fans kick on and pressures back to 40/180 range, good cooling inside cab
0942 - turn off ac switch in cab, rad to low speed, compressor clutch disengage, temp in cab gradually increasing
0944 - turn switch back on, all good with pressures, clutch engagement and cooling in cab
0950 - secure engine, noticed a little condensation on low pressure line, Luke warm to the touch
1000 - started engine for road test ( no gauges, obviously)
1003 - 25 mph thru neighborhood, vent temp 41

Drove 12 miles with no problem on city streets and interstate. Ac vent temp averaged 42. Always very comfortable in cab

Stopped in parking lot and secured engine for 10 mins

Started engine, hot air. Turned ac switch off and back on 30 sec delay, all well again.

Went back to the relay idea, 20 bucks later, no fix.

What tells the condenser/radiator fan to kick to high speed? Ac switch?
How can the compressor clutch be engaged and on pressure change on the gauges?

Thanks in advance for the help.
Find out any solutions facing same issue. Please guide.
 
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